UNIT: Chemical Reactions TOPIC: Properties of Reactions Objectives: Lesson 1 of 3 • • • • To learn how we recognize a chemical reaction has took place To.
Download ReportTranscript UNIT: Chemical Reactions TOPIC: Properties of Reactions Objectives: Lesson 1 of 3 • • • • To learn how we recognize a chemical reaction has took place To.
Slide 1
UNIT: Chemical Reactions
TOPIC: Properties of Reactions
Objectives: Lesson 1 of 3
•
•
•
•
To learn how we recognize a chemical reaction has took place
To learn what a chemical reactions is
To learn how we balance chemical equations
To learn the symbols for each physical state in a chemical
reaction
Quickwrite
In 1-2 sentences answer one of the questions below:
• What sort of clues do think indicate that a chemical reaction is
happening in your car engine????
• What sort of clues indicate a chemical reaction when you drop a
piece of alka selzter in water????
• What are some by products produced when your body breaks
down sugar, C6H12O6????? What are some clues that this
reaction is occuring in your body????? Hint: think of
temperature!!!!
Evidence for a Chemical Reaction
• How do you know a chemical reaction has occurred?
• Chemists look for visual clues such a color or heat
change, a solid forms, bubbles are produced, a flame
occurs
• However, reactions are not always visible
• Sometimes the only signal that a reaction is occurring is
a change in temperature as heat is produced
What are some clues that a
chemical reaction has occurred?
•
•
•
•
•
A color change
A solid forms
Bubbles form
A heat change
A flame is produced
Chemical Reactions
• Chemists have learned that a chemical change always involves a
rearrangement of the ways in which atoms are grouped and combine
with one another
• For example, consider the reaction that occurs with your laboratory
bunsen burners
• In this reaction, methane (CH4) reacts with oxygen (O2) in the air
• As you know, a flame is produce and heat is released
• As the atoms rearrange themselves, two new chemicals are produced
carbon dioxide (CO2), and water (H2O)
CH4 + O2
CO2 + H2O
Chemical
Reactions
Such a change is called a chemical reaction
•
• Notice, the atoms were rearranged, Oxygen combined with Carbon and
Hydrogen to produce 2 new chemicals: Water & Carbon Dioxide
• Chemical reactions obey the Law of Conservation of Matter which states: Atoms
cannot be destroyed, they can only be rearranged
CH4 + O2
CO2
Methane (CH4)
Water(H
Carbon
Dioxide
2O) (CO2)
Oxygen(O2)
H2O
What is a Chemical Reaction?
• A chemical reaction is the change that occurs when
atoms rearrange themselves and form new
compounds
• Chemical reactions obey the first LAW of
conservation of MASS or MATTER which states:
Atoms and matter cannot be created or destroyed,
they can only be rearranged
Chemical Equations
• We represent chemical reactions by writing a
chemical equation in which the chemicals
present before the reaction are on the left of
the arrow, and the chemicals formed by the
reaction are on the right of the arrow
• The arrow indicates the direction of the
change CH4 + O2
CO2 + H2O
Chemical Equations
• In the reaction of methane with oxygen, we have:
CH4 + O2
CO2 + H2O
Reactants
Products
• The chemicals present on the left side of the
equation are known as the reactants
• The chemicals present on the right side of the
equation are known as the products
What is a Chemical Equation?
• An equation that uses the formulas of chemicals
compounds and elements to show the reactants and
products in a chemical change
• Chemicals present before the reaction are on the left of
the arrow (reactants), and the chemicals formed by the
reaction are on the right of the arrow (products)
Ex: CH4 + O2
CO2 + H2O
Balancing Chemical Reactions
• It is important to realize that in a chemical
reaction, atoms are neither created nor
destroyed
• In other words, their must be the same
number of each type of atom on the product
side as on the reactant side of the arrow
••
•
•
•
Balancing Chemical Reactions
In
other
words,
the
reaction
and
table
below
show
Oxygen
Remember,
atoms
beatoms
created
or
destroyed
in
chemical
reactions,
We
can
fix
this
by
putting
in
1atoms,
more
Oxygen
molecule
on1inthe
left
By
the
number
you
can
see
that
the
chemical
Notice,
there
are
2cannot
Oxygen
on
left
side
and
3that
Oxygen
atoms
on
We
group
molecules
by
putting
coefficients
front
ofatom
them:
Thecounting
reaction
below
is together
notof
balanced
is
created
and
2and
Hydrogen
atoms
are
destroyed
they
can only
be
rearranged!
(reactant)
side
1 more
Water
molecule
on
theleft
right
(product)
side
the
right
side;
4byHydrogen
the
side
and 2 apart:
equation
is
balanced
andare
shows
the
actual
numbers
molecules
We can
see
it isalso
notthere
balanced
taking
theonreactants
&ofproducts
Therefore,
the
reaction
cannot
way!
total in
number
of
atoms
musthappen
be
thethis
same
on both
sides
of the
arrow
The
table
now
has
equal
number
of atoms
on
both
sides
of the
equation
Hydrogen
on
the
right
side
involved
this
reaction
CH4
O+2 +2 O2
CO2
H+2+O +2H2O
H
H CH
H
O O
O C O
H OH
O O
Left
Reactant Side
C=
O=
1
2
4
H=
4
9
7
6
9
Total Number of Atoms
Right
H OH
Product Side
O=
1
34
H=
42
C=
Balancing Chemical Reactions
••••• We
In
other
can
fixwords,
this
by
putting
reaction
and
more
table
Water
molecule
show
that
on
the
1front
Oxygen
left(reactant)
atom
By
counting
the
number
of
you
can
see
the
chemical
Remember,
atoms
cannot
be1atoms,
created
orbelow
destroyed
in
chemical
reactions,
group
molecules
byon
putting
coefficients
in
ofon
them:
Notice,
there
is
1the
Oxygen
atoms
left
side
and
2that
Oxygen
atoms
The
reaction
below
istogether
notin
balanced
is
created
and
1only
Hydrogen
molecule
on
the
side and
they
cansee
rearranged!
equation
ismore
balanced
andthe
shows
actual
numbers
atoms
the
right
side;
therefore
chemical
equation
is NOT of
balanced
• side
We
can
it be
is
NOT
balanced
bythe
taking
theright(product)
reactants
& products
•• The
Therefore,
table
thehas
reaction
equal
cannot
number
of
onway!
both
sides
of the
equation
The
total now
number
of
atoms
musthappen
beatoms
the this
same
on both
sides
of the
arrow
molecules
involved
in
this
reaction
apart:
2 H2
H2O + 2 H2O
H OH
H OH
Left
Reactant Side
O=
1
2
42
H=
H H
3
6
6
4
H H
O O
Right
Product Side
O=
2
24
H=
Total Number of Atoms
H+2 + O2
Subscripts and Coefficients
• When balancing chemical equations, it is important to note
that the subscripts can never change
• For example, in the equation below, the subscript of 4 in
methane cannot be changed, neither can the subscripts 2 in
Oxygen, Carbon dioxide and Water
CH4 + 2 O2
CO2 + 2H2O
• Only coefficients can be added by putting whole numbers in
front of the compounds when balancing chemical reactions
How Do we Balance Chemical Equations?
• By placing coefficients in front of each molecule
or compound
• Subscripts cannot be changed!
• Ex: CH4 + 2O2 CO2 + 2H2O
Balancing Chemical Equations
Remember: When balancing chemical equations, it is important to
note that the subscripts can never change!!!!
2
___O
___O
3
2
3
___
2 Mg + ___ O2
___
2 MgO
Practice:
Determine how many atoms of each element are in
each compound below:
1)
2)
3)
4)
2 Na + ___ Cl
___
2
4 Fe + ___
3 O
___
2
___
4 Al + ___
3 O2
2 Na + ___ F
___
2
2
___
NaCl
2 Fe O
___
2 3
___
2 Al2O3
2 NaF
___
Physical States
• In a reaction, we often use symbols to represent the physical state of
the reactants and products
• Look at the reaction below when sodium metal reacts with water:
Na(s) + H2O(l)
H2(g) + NaOH(aq)
• The symbol (s) tells us that Sodium (Na) is in the solid
state
• The symbol (l) tells us the water (H2O) is in the liquid
state
• The symbol (g) tells us the hydrogen (H2) is in the
gaseous state
• Finally, the symbol (aq) tells us that sodium hydroxide
(NaOH) is aqueous or dissolved in water
Symbol
State
(s)
solid
(l)
(g)
(aq)
liquid
gas
aqueous
What do the symbols represent in a
chemical equation?
• The symbols represent the physical state of the
reactants and products
Symbol
State
solid
Na(s) + H2O(l)
H2(g) + NaOH(aq) (s)
(l)
(g)
(aq)
liquid
gas
aqueous
or dissolved
in water
Summary
(you can always write your own summary)
• Explain the Law of Conservation of Mass in your own words
and apply it to chemical reactions:
• What is the difference between the reactants and products
in a chemical reaction?
• Describe the process of balancing chemical reactions, be
sure to explain how you count atoms on both sides of the
equation
• What can you not change when balancing chemical
reactions?
• Is the reaction below balanced? Explain why or why not:
K + Cl2 KCl
Slide 2
UNIT: Chemical Reactions
TOPIC: Properties of Reactions
Objectives: Lesson 1 of 3
•
•
•
•
To learn how we recognize a chemical reaction has took place
To learn what a chemical reactions is
To learn how we balance chemical equations
To learn the symbols for each physical state in a chemical
reaction
Quickwrite
In 1-2 sentences answer one of the questions below:
• What sort of clues do think indicate that a chemical reaction is
happening in your car engine????
• What sort of clues indicate a chemical reaction when you drop a
piece of alka selzter in water????
• What are some by products produced when your body breaks
down sugar, C6H12O6????? What are some clues that this
reaction is occuring in your body????? Hint: think of
temperature!!!!
Evidence for a Chemical Reaction
• How do you know a chemical reaction has occurred?
• Chemists look for visual clues such a color or heat
change, a solid forms, bubbles are produced, a flame
occurs
• However, reactions are not always visible
• Sometimes the only signal that a reaction is occurring is
a change in temperature as heat is produced
What are some clues that a
chemical reaction has occurred?
•
•
•
•
•
A color change
A solid forms
Bubbles form
A heat change
A flame is produced
Chemical Reactions
• Chemists have learned that a chemical change always involves a
rearrangement of the ways in which atoms are grouped and combine
with one another
• For example, consider the reaction that occurs with your laboratory
bunsen burners
• In this reaction, methane (CH4) reacts with oxygen (O2) in the air
• As you know, a flame is produce and heat is released
• As the atoms rearrange themselves, two new chemicals are produced
carbon dioxide (CO2), and water (H2O)
CH4 + O2
CO2 + H2O
Chemical
Reactions
Such a change is called a chemical reaction
•
• Notice, the atoms were rearranged, Oxygen combined with Carbon and
Hydrogen to produce 2 new chemicals: Water & Carbon Dioxide
• Chemical reactions obey the Law of Conservation of Matter which states: Atoms
cannot be destroyed, they can only be rearranged
CH4 + O2
CO2
Methane (CH4)
Water(H
Carbon
Dioxide
2O) (CO2)
Oxygen(O2)
H2O
What is a Chemical Reaction?
• A chemical reaction is the change that occurs when
atoms rearrange themselves and form new
compounds
• Chemical reactions obey the first LAW of
conservation of MASS or MATTER which states:
Atoms and matter cannot be created or destroyed,
they can only be rearranged
Chemical Equations
• We represent chemical reactions by writing a
chemical equation in which the chemicals
present before the reaction are on the left of
the arrow, and the chemicals formed by the
reaction are on the right of the arrow
• The arrow indicates the direction of the
change CH4 + O2
CO2 + H2O
Chemical Equations
• In the reaction of methane with oxygen, we have:
CH4 + O2
CO2 + H2O
Reactants
Products
• The chemicals present on the left side of the
equation are known as the reactants
• The chemicals present on the right side of the
equation are known as the products
What is a Chemical Equation?
• An equation that uses the formulas of chemicals
compounds and elements to show the reactants and
products in a chemical change
• Chemicals present before the reaction are on the left of
the arrow (reactants), and the chemicals formed by the
reaction are on the right of the arrow (products)
Ex: CH4 + O2
CO2 + H2O
Balancing Chemical Reactions
• It is important to realize that in a chemical
reaction, atoms are neither created nor
destroyed
• In other words, their must be the same
number of each type of atom on the product
side as on the reactant side of the arrow
••
•
•
•
Balancing Chemical Reactions
In
other
words,
the
reaction
and
table
below
show
Oxygen
Remember,
atoms
beatoms
created
or
destroyed
in
chemical
reactions,
We
can
fix
this
by
putting
in
1atoms,
more
Oxygen
molecule
on1inthe
left
By
the
number
you
can
see
that
the
chemical
Notice,
there
are
2cannot
Oxygen
on
left
side
and
3that
Oxygen
atoms
on
We
group
molecules
by
putting
coefficients
front
ofatom
them:
Thecounting
reaction
below
is together
notof
balanced
is
created
and
2and
Hydrogen
atoms
are
destroyed
they
can only
be
rearranged!
(reactant)
side
1 more
Water
molecule
on
theleft
right
(product)
side
the
right
side;
4byHydrogen
the
side
and 2 apart:
equation
is
balanced
andare
shows
the
actual
numbers
molecules
We can
see
it isalso
notthere
balanced
taking
theonreactants
&ofproducts
Therefore,
the
reaction
cannot
way!
total in
number
of
atoms
musthappen
be
thethis
same
on both
sides
of the
arrow
The
table
now
has
equal
number
of atoms
on
both
sides
of the
equation
Hydrogen
on
the
right
side
involved
this
reaction
CH4
O+2 +2 O2
CO2
H+2+O +2H2O
H
H CH
H
O O
O C O
H OH
O O
Left
Reactant Side
C=
O=
1
2
4
H=
4
9
7
6
9
Total Number of Atoms
Right
H OH
Product Side
O=
1
34
H=
42
C=
Balancing Chemical Reactions
••••• We
In
other
can
fixwords,
this
by
putting
reaction
and
more
table
Water
molecule
show
that
on
the
1front
Oxygen
left(reactant)
atom
By
counting
the
number
of
you
can
see
the
chemical
Remember,
atoms
cannot
be1atoms,
created
orbelow
destroyed
in
chemical
reactions,
group
molecules
byon
putting
coefficients
in
ofon
them:
Notice,
there
is
1the
Oxygen
atoms
left
side
and
2that
Oxygen
atoms
The
reaction
below
istogether
notin
balanced
is
created
and
1only
Hydrogen
molecule
on
the
side and
they
cansee
rearranged!
equation
ismore
balanced
andthe
shows
actual
numbers
atoms
the
right
side;
therefore
chemical
equation
is NOT of
balanced
• side
We
can
it be
is
NOT
balanced
bythe
taking
theright(product)
reactants
& products
•• The
Therefore,
table
thehas
reaction
equal
cannot
number
of
onway!
both
sides
of the
equation
The
total now
number
of
atoms
musthappen
beatoms
the this
same
on both
sides
of the
arrow
molecules
involved
in
this
reaction
apart:
2 H2
H2O + 2 H2O
H OH
H OH
Left
Reactant Side
O=
1
2
42
H=
H H
3
6
6
4
H H
O O
Right
Product Side
O=
2
24
H=
Total Number of Atoms
H+2 + O2
Subscripts and Coefficients
• When balancing chemical equations, it is important to note
that the subscripts can never change
• For example, in the equation below, the subscript of 4 in
methane cannot be changed, neither can the subscripts 2 in
Oxygen, Carbon dioxide and Water
CH4 + 2 O2
CO2 + 2H2O
• Only coefficients can be added by putting whole numbers in
front of the compounds when balancing chemical reactions
How Do we Balance Chemical Equations?
• By placing coefficients in front of each molecule
or compound
• Subscripts cannot be changed!
• Ex: CH4 + 2O2 CO2 + 2H2O
Balancing Chemical Equations
Remember: When balancing chemical equations, it is important to
note that the subscripts can never change!!!!
2
___O
___O
3
2
3
___
2 Mg + ___ O2
___
2 MgO
Practice:
Determine how many atoms of each element are in
each compound below:
1)
2)
3)
4)
2 Na + ___ Cl
___
2
4 Fe + ___
3 O
___
2
___
4 Al + ___
3 O2
2 Na + ___ F
___
2
2
___
NaCl
2 Fe O
___
2 3
___
2 Al2O3
2 NaF
___
Physical States
• In a reaction, we often use symbols to represent the physical state of
the reactants and products
• Look at the reaction below when sodium metal reacts with water:
Na(s) + H2O(l)
H2(g) + NaOH(aq)
• The symbol (s) tells us that Sodium (Na) is in the solid
state
• The symbol (l) tells us the water (H2O) is in the liquid
state
• The symbol (g) tells us the hydrogen (H2) is in the
gaseous state
• Finally, the symbol (aq) tells us that sodium hydroxide
(NaOH) is aqueous or dissolved in water
Symbol
State
(s)
solid
(l)
(g)
(aq)
liquid
gas
aqueous
What do the symbols represent in a
chemical equation?
• The symbols represent the physical state of the
reactants and products
Symbol
State
solid
Na(s) + H2O(l)
H2(g) + NaOH(aq) (s)
(l)
(g)
(aq)
liquid
gas
aqueous
or dissolved
in water
Summary
(you can always write your own summary)
• Explain the Law of Conservation of Mass in your own words
and apply it to chemical reactions:
• What is the difference between the reactants and products
in a chemical reaction?
• Describe the process of balancing chemical reactions, be
sure to explain how you count atoms on both sides of the
equation
• What can you not change when balancing chemical
reactions?
• Is the reaction below balanced? Explain why or why not:
K + Cl2 KCl
Slide 3
UNIT: Chemical Reactions
TOPIC: Properties of Reactions
Objectives: Lesson 1 of 3
•
•
•
•
To learn how we recognize a chemical reaction has took place
To learn what a chemical reactions is
To learn how we balance chemical equations
To learn the symbols for each physical state in a chemical
reaction
Quickwrite
In 1-2 sentences answer one of the questions below:
• What sort of clues do think indicate that a chemical reaction is
happening in your car engine????
• What sort of clues indicate a chemical reaction when you drop a
piece of alka selzter in water????
• What are some by products produced when your body breaks
down sugar, C6H12O6????? What are some clues that this
reaction is occuring in your body????? Hint: think of
temperature!!!!
Evidence for a Chemical Reaction
• How do you know a chemical reaction has occurred?
• Chemists look for visual clues such a color or heat
change, a solid forms, bubbles are produced, a flame
occurs
• However, reactions are not always visible
• Sometimes the only signal that a reaction is occurring is
a change in temperature as heat is produced
What are some clues that a
chemical reaction has occurred?
•
•
•
•
•
A color change
A solid forms
Bubbles form
A heat change
A flame is produced
Chemical Reactions
• Chemists have learned that a chemical change always involves a
rearrangement of the ways in which atoms are grouped and combine
with one another
• For example, consider the reaction that occurs with your laboratory
bunsen burners
• In this reaction, methane (CH4) reacts with oxygen (O2) in the air
• As you know, a flame is produce and heat is released
• As the atoms rearrange themselves, two new chemicals are produced
carbon dioxide (CO2), and water (H2O)
CH4 + O2
CO2 + H2O
Chemical
Reactions
Such a change is called a chemical reaction
•
• Notice, the atoms were rearranged, Oxygen combined with Carbon and
Hydrogen to produce 2 new chemicals: Water & Carbon Dioxide
• Chemical reactions obey the Law of Conservation of Matter which states: Atoms
cannot be destroyed, they can only be rearranged
CH4 + O2
CO2
Methane (CH4)
Water(H
Carbon
Dioxide
2O) (CO2)
Oxygen(O2)
H2O
What is a Chemical Reaction?
• A chemical reaction is the change that occurs when
atoms rearrange themselves and form new
compounds
• Chemical reactions obey the first LAW of
conservation of MASS or MATTER which states:
Atoms and matter cannot be created or destroyed,
they can only be rearranged
Chemical Equations
• We represent chemical reactions by writing a
chemical equation in which the chemicals
present before the reaction are on the left of
the arrow, and the chemicals formed by the
reaction are on the right of the arrow
• The arrow indicates the direction of the
change CH4 + O2
CO2 + H2O
Chemical Equations
• In the reaction of methane with oxygen, we have:
CH4 + O2
CO2 + H2O
Reactants
Products
• The chemicals present on the left side of the
equation are known as the reactants
• The chemicals present on the right side of the
equation are known as the products
What is a Chemical Equation?
• An equation that uses the formulas of chemicals
compounds and elements to show the reactants and
products in a chemical change
• Chemicals present before the reaction are on the left of
the arrow (reactants), and the chemicals formed by the
reaction are on the right of the arrow (products)
Ex: CH4 + O2
CO2 + H2O
Balancing Chemical Reactions
• It is important to realize that in a chemical
reaction, atoms are neither created nor
destroyed
• In other words, their must be the same
number of each type of atom on the product
side as on the reactant side of the arrow
••
•
•
•
Balancing Chemical Reactions
In
other
words,
the
reaction
and
table
below
show
Oxygen
Remember,
atoms
beatoms
created
or
destroyed
in
chemical
reactions,
We
can
fix
this
by
putting
in
1atoms,
more
Oxygen
molecule
on1inthe
left
By
the
number
you
can
see
that
the
chemical
Notice,
there
are
2cannot
Oxygen
on
left
side
and
3that
Oxygen
atoms
on
We
group
molecules
by
putting
coefficients
front
ofatom
them:
Thecounting
reaction
below
is together
notof
balanced
is
created
and
2and
Hydrogen
atoms
are
destroyed
they
can only
be
rearranged!
(reactant)
side
1 more
Water
molecule
on
theleft
right
(product)
side
the
right
side;
4byHydrogen
the
side
and 2 apart:
equation
is
balanced
andare
shows
the
actual
numbers
molecules
We can
see
it isalso
notthere
balanced
taking
theonreactants
&ofproducts
Therefore,
the
reaction
cannot
way!
total in
number
of
atoms
musthappen
be
thethis
same
on both
sides
of the
arrow
The
table
now
has
equal
number
of atoms
on
both
sides
of the
equation
Hydrogen
on
the
right
side
involved
this
reaction
CH4
O+2 +2 O2
CO2
H+2+O +2H2O
H
H CH
H
O O
O C O
H OH
O O
Left
Reactant Side
C=
O=
1
2
4
H=
4
9
7
6
9
Total Number of Atoms
Right
H OH
Product Side
O=
1
34
H=
42
C=
Balancing Chemical Reactions
••••• We
In
other
can
fixwords,
this
by
putting
reaction
and
more
table
Water
molecule
show
that
on
the
1front
Oxygen
left(reactant)
atom
By
counting
the
number
of
you
can
see
the
chemical
Remember,
atoms
cannot
be1atoms,
created
orbelow
destroyed
in
chemical
reactions,
group
molecules
byon
putting
coefficients
in
ofon
them:
Notice,
there
is
1the
Oxygen
atoms
left
side
and
2that
Oxygen
atoms
The
reaction
below
istogether
notin
balanced
is
created
and
1only
Hydrogen
molecule
on
the
side and
they
cansee
rearranged!
equation
ismore
balanced
andthe
shows
actual
numbers
atoms
the
right
side;
therefore
chemical
equation
is NOT of
balanced
• side
We
can
it be
is
NOT
balanced
bythe
taking
theright(product)
reactants
& products
•• The
Therefore,
table
thehas
reaction
equal
cannot
number
of
onway!
both
sides
of the
equation
The
total now
number
of
atoms
musthappen
beatoms
the this
same
on both
sides
of the
arrow
molecules
involved
in
this
reaction
apart:
2 H2
H2O + 2 H2O
H OH
H OH
Left
Reactant Side
O=
1
2
42
H=
H H
3
6
6
4
H H
O O
Right
Product Side
O=
2
24
H=
Total Number of Atoms
H+2 + O2
Subscripts and Coefficients
• When balancing chemical equations, it is important to note
that the subscripts can never change
• For example, in the equation below, the subscript of 4 in
methane cannot be changed, neither can the subscripts 2 in
Oxygen, Carbon dioxide and Water
CH4 + 2 O2
CO2 + 2H2O
• Only coefficients can be added by putting whole numbers in
front of the compounds when balancing chemical reactions
How Do we Balance Chemical Equations?
• By placing coefficients in front of each molecule
or compound
• Subscripts cannot be changed!
• Ex: CH4 + 2O2 CO2 + 2H2O
Balancing Chemical Equations
Remember: When balancing chemical equations, it is important to
note that the subscripts can never change!!!!
2
___O
___O
3
2
3
___
2 Mg + ___ O2
___
2 MgO
Practice:
Determine how many atoms of each element are in
each compound below:
1)
2)
3)
4)
2 Na + ___ Cl
___
2
4 Fe + ___
3 O
___
2
___
4 Al + ___
3 O2
2 Na + ___ F
___
2
2
___
NaCl
2 Fe O
___
2 3
___
2 Al2O3
2 NaF
___
Physical States
• In a reaction, we often use symbols to represent the physical state of
the reactants and products
• Look at the reaction below when sodium metal reacts with water:
Na(s) + H2O(l)
H2(g) + NaOH(aq)
• The symbol (s) tells us that Sodium (Na) is in the solid
state
• The symbol (l) tells us the water (H2O) is in the liquid
state
• The symbol (g) tells us the hydrogen (H2) is in the
gaseous state
• Finally, the symbol (aq) tells us that sodium hydroxide
(NaOH) is aqueous or dissolved in water
Symbol
State
(s)
solid
(l)
(g)
(aq)
liquid
gas
aqueous
What do the symbols represent in a
chemical equation?
• The symbols represent the physical state of the
reactants and products
Symbol
State
solid
Na(s) + H2O(l)
H2(g) + NaOH(aq) (s)
(l)
(g)
(aq)
liquid
gas
aqueous
or dissolved
in water
Summary
(you can always write your own summary)
• Explain the Law of Conservation of Mass in your own words
and apply it to chemical reactions:
• What is the difference between the reactants and products
in a chemical reaction?
• Describe the process of balancing chemical reactions, be
sure to explain how you count atoms on both sides of the
equation
• What can you not change when balancing chemical
reactions?
• Is the reaction below balanced? Explain why or why not:
K + Cl2 KCl
Slide 4
UNIT: Chemical Reactions
TOPIC: Properties of Reactions
Objectives: Lesson 1 of 3
•
•
•
•
To learn how we recognize a chemical reaction has took place
To learn what a chemical reactions is
To learn how we balance chemical equations
To learn the symbols for each physical state in a chemical
reaction
Quickwrite
In 1-2 sentences answer one of the questions below:
• What sort of clues do think indicate that a chemical reaction is
happening in your car engine????
• What sort of clues indicate a chemical reaction when you drop a
piece of alka selzter in water????
• What are some by products produced when your body breaks
down sugar, C6H12O6????? What are some clues that this
reaction is occuring in your body????? Hint: think of
temperature!!!!
Evidence for a Chemical Reaction
• How do you know a chemical reaction has occurred?
• Chemists look for visual clues such a color or heat
change, a solid forms, bubbles are produced, a flame
occurs
• However, reactions are not always visible
• Sometimes the only signal that a reaction is occurring is
a change in temperature as heat is produced
What are some clues that a
chemical reaction has occurred?
•
•
•
•
•
A color change
A solid forms
Bubbles form
A heat change
A flame is produced
Chemical Reactions
• Chemists have learned that a chemical change always involves a
rearrangement of the ways in which atoms are grouped and combine
with one another
• For example, consider the reaction that occurs with your laboratory
bunsen burners
• In this reaction, methane (CH4) reacts with oxygen (O2) in the air
• As you know, a flame is produce and heat is released
• As the atoms rearrange themselves, two new chemicals are produced
carbon dioxide (CO2), and water (H2O)
CH4 + O2
CO2 + H2O
Chemical
Reactions
Such a change is called a chemical reaction
•
• Notice, the atoms were rearranged, Oxygen combined with Carbon and
Hydrogen to produce 2 new chemicals: Water & Carbon Dioxide
• Chemical reactions obey the Law of Conservation of Matter which states: Atoms
cannot be destroyed, they can only be rearranged
CH4 + O2
CO2
Methane (CH4)
Water(H
Carbon
Dioxide
2O) (CO2)
Oxygen(O2)
H2O
What is a Chemical Reaction?
• A chemical reaction is the change that occurs when
atoms rearrange themselves and form new
compounds
• Chemical reactions obey the first LAW of
conservation of MASS or MATTER which states:
Atoms and matter cannot be created or destroyed,
they can only be rearranged
Chemical Equations
• We represent chemical reactions by writing a
chemical equation in which the chemicals
present before the reaction are on the left of
the arrow, and the chemicals formed by the
reaction are on the right of the arrow
• The arrow indicates the direction of the
change CH4 + O2
CO2 + H2O
Chemical Equations
• In the reaction of methane with oxygen, we have:
CH4 + O2
CO2 + H2O
Reactants
Products
• The chemicals present on the left side of the
equation are known as the reactants
• The chemicals present on the right side of the
equation are known as the products
What is a Chemical Equation?
• An equation that uses the formulas of chemicals
compounds and elements to show the reactants and
products in a chemical change
• Chemicals present before the reaction are on the left of
the arrow (reactants), and the chemicals formed by the
reaction are on the right of the arrow (products)
Ex: CH4 + O2
CO2 + H2O
Balancing Chemical Reactions
• It is important to realize that in a chemical
reaction, atoms are neither created nor
destroyed
• In other words, their must be the same
number of each type of atom on the product
side as on the reactant side of the arrow
••
•
•
•
Balancing Chemical Reactions
In
other
words,
the
reaction
and
table
below
show
Oxygen
Remember,
atoms
beatoms
created
or
destroyed
in
chemical
reactions,
We
can
fix
this
by
putting
in
1atoms,
more
Oxygen
molecule
on1inthe
left
By
the
number
you
can
see
that
the
chemical
Notice,
there
are
2cannot
Oxygen
on
left
side
and
3that
Oxygen
atoms
on
We
group
molecules
by
putting
coefficients
front
ofatom
them:
Thecounting
reaction
below
is together
notof
balanced
is
created
and
2and
Hydrogen
atoms
are
destroyed
they
can only
be
rearranged!
(reactant)
side
1 more
Water
molecule
on
theleft
right
(product)
side
the
right
side;
4byHydrogen
the
side
and 2 apart:
equation
is
balanced
andare
shows
the
actual
numbers
molecules
We can
see
it isalso
notthere
balanced
taking
theonreactants
&ofproducts
Therefore,
the
reaction
cannot
way!
total in
number
of
atoms
musthappen
be
thethis
same
on both
sides
of the
arrow
The
table
now
has
equal
number
of atoms
on
both
sides
of the
equation
Hydrogen
on
the
right
side
involved
this
reaction
CH4
O+2 +2 O2
CO2
H+2+O +2H2O
H
H CH
H
O O
O C O
H OH
O O
Left
Reactant Side
C=
O=
1
2
4
H=
4
9
7
6
9
Total Number of Atoms
Right
H OH
Product Side
O=
1
34
H=
42
C=
Balancing Chemical Reactions
••••• We
In
other
can
fixwords,
this
by
putting
reaction
and
more
table
Water
molecule
show
that
on
the
1front
Oxygen
left(reactant)
atom
By
counting
the
number
of
you
can
see
the
chemical
Remember,
atoms
cannot
be1atoms,
created
orbelow
destroyed
in
chemical
reactions,
group
molecules
byon
putting
coefficients
in
ofon
them:
Notice,
there
is
1the
Oxygen
atoms
left
side
and
2that
Oxygen
atoms
The
reaction
below
istogether
notin
balanced
is
created
and
1only
Hydrogen
molecule
on
the
side and
they
cansee
rearranged!
equation
ismore
balanced
andthe
shows
actual
numbers
atoms
the
right
side;
therefore
chemical
equation
is NOT of
balanced
• side
We
can
it be
is
NOT
balanced
bythe
taking
theright(product)
reactants
& products
•• The
Therefore,
table
thehas
reaction
equal
cannot
number
of
onway!
both
sides
of the
equation
The
total now
number
of
atoms
musthappen
beatoms
the this
same
on both
sides
of the
arrow
molecules
involved
in
this
reaction
apart:
2 H2
H2O + 2 H2O
H OH
H OH
Left
Reactant Side
O=
1
2
42
H=
H H
3
6
6
4
H H
O O
Right
Product Side
O=
2
24
H=
Total Number of Atoms
H+2 + O2
Subscripts and Coefficients
• When balancing chemical equations, it is important to note
that the subscripts can never change
• For example, in the equation below, the subscript of 4 in
methane cannot be changed, neither can the subscripts 2 in
Oxygen, Carbon dioxide and Water
CH4 + 2 O2
CO2 + 2H2O
• Only coefficients can be added by putting whole numbers in
front of the compounds when balancing chemical reactions
How Do we Balance Chemical Equations?
• By placing coefficients in front of each molecule
or compound
• Subscripts cannot be changed!
• Ex: CH4 + 2O2 CO2 + 2H2O
Balancing Chemical Equations
Remember: When balancing chemical equations, it is important to
note that the subscripts can never change!!!!
2
___O
___O
3
2
3
___
2 Mg + ___ O2
___
2 MgO
Practice:
Determine how many atoms of each element are in
each compound below:
1)
2)
3)
4)
2 Na + ___ Cl
___
2
4 Fe + ___
3 O
___
2
___
4 Al + ___
3 O2
2 Na + ___ F
___
2
2
___
NaCl
2 Fe O
___
2 3
___
2 Al2O3
2 NaF
___
Physical States
• In a reaction, we often use symbols to represent the physical state of
the reactants and products
• Look at the reaction below when sodium metal reacts with water:
Na(s) + H2O(l)
H2(g) + NaOH(aq)
• The symbol (s) tells us that Sodium (Na) is in the solid
state
• The symbol (l) tells us the water (H2O) is in the liquid
state
• The symbol (g) tells us the hydrogen (H2) is in the
gaseous state
• Finally, the symbol (aq) tells us that sodium hydroxide
(NaOH) is aqueous or dissolved in water
Symbol
State
(s)
solid
(l)
(g)
(aq)
liquid
gas
aqueous
What do the symbols represent in a
chemical equation?
• The symbols represent the physical state of the
reactants and products
Symbol
State
solid
Na(s) + H2O(l)
H2(g) + NaOH(aq) (s)
(l)
(g)
(aq)
liquid
gas
aqueous
or dissolved
in water
Summary
(you can always write your own summary)
• Explain the Law of Conservation of Mass in your own words
and apply it to chemical reactions:
• What is the difference between the reactants and products
in a chemical reaction?
• Describe the process of balancing chemical reactions, be
sure to explain how you count atoms on both sides of the
equation
• What can you not change when balancing chemical
reactions?
• Is the reaction below balanced? Explain why or why not:
K + Cl2 KCl
Slide 5
UNIT: Chemical Reactions
TOPIC: Properties of Reactions
Objectives: Lesson 1 of 3
•
•
•
•
To learn how we recognize a chemical reaction has took place
To learn what a chemical reactions is
To learn how we balance chemical equations
To learn the symbols for each physical state in a chemical
reaction
Quickwrite
In 1-2 sentences answer one of the questions below:
• What sort of clues do think indicate that a chemical reaction is
happening in your car engine????
• What sort of clues indicate a chemical reaction when you drop a
piece of alka selzter in water????
• What are some by products produced when your body breaks
down sugar, C6H12O6????? What are some clues that this
reaction is occuring in your body????? Hint: think of
temperature!!!!
Evidence for a Chemical Reaction
• How do you know a chemical reaction has occurred?
• Chemists look for visual clues such a color or heat
change, a solid forms, bubbles are produced, a flame
occurs
• However, reactions are not always visible
• Sometimes the only signal that a reaction is occurring is
a change in temperature as heat is produced
What are some clues that a
chemical reaction has occurred?
•
•
•
•
•
A color change
A solid forms
Bubbles form
A heat change
A flame is produced
Chemical Reactions
• Chemists have learned that a chemical change always involves a
rearrangement of the ways in which atoms are grouped and combine
with one another
• For example, consider the reaction that occurs with your laboratory
bunsen burners
• In this reaction, methane (CH4) reacts with oxygen (O2) in the air
• As you know, a flame is produce and heat is released
• As the atoms rearrange themselves, two new chemicals are produced
carbon dioxide (CO2), and water (H2O)
CH4 + O2
CO2 + H2O
Chemical
Reactions
Such a change is called a chemical reaction
•
• Notice, the atoms were rearranged, Oxygen combined with Carbon and
Hydrogen to produce 2 new chemicals: Water & Carbon Dioxide
• Chemical reactions obey the Law of Conservation of Matter which states: Atoms
cannot be destroyed, they can only be rearranged
CH4 + O2
CO2
Methane (CH4)
Water(H
Carbon
Dioxide
2O) (CO2)
Oxygen(O2)
H2O
What is a Chemical Reaction?
• A chemical reaction is the change that occurs when
atoms rearrange themselves and form new
compounds
• Chemical reactions obey the first LAW of
conservation of MASS or MATTER which states:
Atoms and matter cannot be created or destroyed,
they can only be rearranged
Chemical Equations
• We represent chemical reactions by writing a
chemical equation in which the chemicals
present before the reaction are on the left of
the arrow, and the chemicals formed by the
reaction are on the right of the arrow
• The arrow indicates the direction of the
change CH4 + O2
CO2 + H2O
Chemical Equations
• In the reaction of methane with oxygen, we have:
CH4 + O2
CO2 + H2O
Reactants
Products
• The chemicals present on the left side of the
equation are known as the reactants
• The chemicals present on the right side of the
equation are known as the products
What is a Chemical Equation?
• An equation that uses the formulas of chemicals
compounds and elements to show the reactants and
products in a chemical change
• Chemicals present before the reaction are on the left of
the arrow (reactants), and the chemicals formed by the
reaction are on the right of the arrow (products)
Ex: CH4 + O2
CO2 + H2O
Balancing Chemical Reactions
• It is important to realize that in a chemical
reaction, atoms are neither created nor
destroyed
• In other words, their must be the same
number of each type of atom on the product
side as on the reactant side of the arrow
••
•
•
•
Balancing Chemical Reactions
In
other
words,
the
reaction
and
table
below
show
Oxygen
Remember,
atoms
beatoms
created
or
destroyed
in
chemical
reactions,
We
can
fix
this
by
putting
in
1atoms,
more
Oxygen
molecule
on1inthe
left
By
the
number
you
can
see
that
the
chemical
Notice,
there
are
2cannot
Oxygen
on
left
side
and
3that
Oxygen
atoms
on
We
group
molecules
by
putting
coefficients
front
ofatom
them:
Thecounting
reaction
below
is together
notof
balanced
is
created
and
2and
Hydrogen
atoms
are
destroyed
they
can only
be
rearranged!
(reactant)
side
1 more
Water
molecule
on
theleft
right
(product)
side
the
right
side;
4byHydrogen
the
side
and 2 apart:
equation
is
balanced
andare
shows
the
actual
numbers
molecules
We can
see
it isalso
notthere
balanced
taking
theonreactants
&ofproducts
Therefore,
the
reaction
cannot
way!
total in
number
of
atoms
musthappen
be
thethis
same
on both
sides
of the
arrow
The
table
now
has
equal
number
of atoms
on
both
sides
of the
equation
Hydrogen
on
the
right
side
involved
this
reaction
CH4
O+2 +2 O2
CO2
H+2+O +2H2O
H
H CH
H
O O
O C O
H OH
O O
Left
Reactant Side
C=
O=
1
2
4
H=
4
9
7
6
9
Total Number of Atoms
Right
H OH
Product Side
O=
1
34
H=
42
C=
Balancing Chemical Reactions
••••• We
In
other
can
fixwords,
this
by
putting
reaction
and
more
table
Water
molecule
show
that
on
the
1front
Oxygen
left(reactant)
atom
By
counting
the
number
of
you
can
see
the
chemical
Remember,
atoms
cannot
be1atoms,
created
orbelow
destroyed
in
chemical
reactions,
group
molecules
byon
putting
coefficients
in
ofon
them:
Notice,
there
is
1the
Oxygen
atoms
left
side
and
2that
Oxygen
atoms
The
reaction
below
istogether
notin
balanced
is
created
and
1only
Hydrogen
molecule
on
the
side and
they
cansee
rearranged!
equation
ismore
balanced
andthe
shows
actual
numbers
atoms
the
right
side;
therefore
chemical
equation
is NOT of
balanced
• side
We
can
it be
is
NOT
balanced
bythe
taking
theright(product)
reactants
& products
•• The
Therefore,
table
thehas
reaction
equal
cannot
number
of
onway!
both
sides
of the
equation
The
total now
number
of
atoms
musthappen
beatoms
the this
same
on both
sides
of the
arrow
molecules
involved
in
this
reaction
apart:
2 H2
H2O + 2 H2O
H OH
H OH
Left
Reactant Side
O=
1
2
42
H=
H H
3
6
6
4
H H
O O
Right
Product Side
O=
2
24
H=
Total Number of Atoms
H+2 + O2
Subscripts and Coefficients
• When balancing chemical equations, it is important to note
that the subscripts can never change
• For example, in the equation below, the subscript of 4 in
methane cannot be changed, neither can the subscripts 2 in
Oxygen, Carbon dioxide and Water
CH4 + 2 O2
CO2 + 2H2O
• Only coefficients can be added by putting whole numbers in
front of the compounds when balancing chemical reactions
How Do we Balance Chemical Equations?
• By placing coefficients in front of each molecule
or compound
• Subscripts cannot be changed!
• Ex: CH4 + 2O2 CO2 + 2H2O
Balancing Chemical Equations
Remember: When balancing chemical equations, it is important to
note that the subscripts can never change!!!!
2
___O
___O
3
2
3
___
2 Mg + ___ O2
___
2 MgO
Practice:
Determine how many atoms of each element are in
each compound below:
1)
2)
3)
4)
2 Na + ___ Cl
___
2
4 Fe + ___
3 O
___
2
___
4 Al + ___
3 O2
2 Na + ___ F
___
2
2
___
NaCl
2 Fe O
___
2 3
___
2 Al2O3
2 NaF
___
Physical States
• In a reaction, we often use symbols to represent the physical state of
the reactants and products
• Look at the reaction below when sodium metal reacts with water:
Na(s) + H2O(l)
H2(g) + NaOH(aq)
• The symbol (s) tells us that Sodium (Na) is in the solid
state
• The symbol (l) tells us the water (H2O) is in the liquid
state
• The symbol (g) tells us the hydrogen (H2) is in the
gaseous state
• Finally, the symbol (aq) tells us that sodium hydroxide
(NaOH) is aqueous or dissolved in water
Symbol
State
(s)
solid
(l)
(g)
(aq)
liquid
gas
aqueous
What do the symbols represent in a
chemical equation?
• The symbols represent the physical state of the
reactants and products
Symbol
State
solid
Na(s) + H2O(l)
H2(g) + NaOH(aq) (s)
(l)
(g)
(aq)
liquid
gas
aqueous
or dissolved
in water
Summary
(you can always write your own summary)
• Explain the Law of Conservation of Mass in your own words
and apply it to chemical reactions:
• What is the difference between the reactants and products
in a chemical reaction?
• Describe the process of balancing chemical reactions, be
sure to explain how you count atoms on both sides of the
equation
• What can you not change when balancing chemical
reactions?
• Is the reaction below balanced? Explain why or why not:
K + Cl2 KCl
Slide 6
UNIT: Chemical Reactions
TOPIC: Properties of Reactions
Objectives: Lesson 1 of 3
•
•
•
•
To learn how we recognize a chemical reaction has took place
To learn what a chemical reactions is
To learn how we balance chemical equations
To learn the symbols for each physical state in a chemical
reaction
Quickwrite
In 1-2 sentences answer one of the questions below:
• What sort of clues do think indicate that a chemical reaction is
happening in your car engine????
• What sort of clues indicate a chemical reaction when you drop a
piece of alka selzter in water????
• What are some by products produced when your body breaks
down sugar, C6H12O6????? What are some clues that this
reaction is occuring in your body????? Hint: think of
temperature!!!!
Evidence for a Chemical Reaction
• How do you know a chemical reaction has occurred?
• Chemists look for visual clues such a color or heat
change, a solid forms, bubbles are produced, a flame
occurs
• However, reactions are not always visible
• Sometimes the only signal that a reaction is occurring is
a change in temperature as heat is produced
What are some clues that a
chemical reaction has occurred?
•
•
•
•
•
A color change
A solid forms
Bubbles form
A heat change
A flame is produced
Chemical Reactions
• Chemists have learned that a chemical change always involves a
rearrangement of the ways in which atoms are grouped and combine
with one another
• For example, consider the reaction that occurs with your laboratory
bunsen burners
• In this reaction, methane (CH4) reacts with oxygen (O2) in the air
• As you know, a flame is produce and heat is released
• As the atoms rearrange themselves, two new chemicals are produced
carbon dioxide (CO2), and water (H2O)
CH4 + O2
CO2 + H2O
Chemical
Reactions
Such a change is called a chemical reaction
•
• Notice, the atoms were rearranged, Oxygen combined with Carbon and
Hydrogen to produce 2 new chemicals: Water & Carbon Dioxide
• Chemical reactions obey the Law of Conservation of Matter which states: Atoms
cannot be destroyed, they can only be rearranged
CH4 + O2
CO2
Methane (CH4)
Water(H
Carbon
Dioxide
2O) (CO2)
Oxygen(O2)
H2O
What is a Chemical Reaction?
• A chemical reaction is the change that occurs when
atoms rearrange themselves and form new
compounds
• Chemical reactions obey the first LAW of
conservation of MASS or MATTER which states:
Atoms and matter cannot be created or destroyed,
they can only be rearranged
Chemical Equations
• We represent chemical reactions by writing a
chemical equation in which the chemicals
present before the reaction are on the left of
the arrow, and the chemicals formed by the
reaction are on the right of the arrow
• The arrow indicates the direction of the
change CH4 + O2
CO2 + H2O
Chemical Equations
• In the reaction of methane with oxygen, we have:
CH4 + O2
CO2 + H2O
Reactants
Products
• The chemicals present on the left side of the
equation are known as the reactants
• The chemicals present on the right side of the
equation are known as the products
What is a Chemical Equation?
• An equation that uses the formulas of chemicals
compounds and elements to show the reactants and
products in a chemical change
• Chemicals present before the reaction are on the left of
the arrow (reactants), and the chemicals formed by the
reaction are on the right of the arrow (products)
Ex: CH4 + O2
CO2 + H2O
Balancing Chemical Reactions
• It is important to realize that in a chemical
reaction, atoms are neither created nor
destroyed
• In other words, their must be the same
number of each type of atom on the product
side as on the reactant side of the arrow
••
•
•
•
Balancing Chemical Reactions
In
other
words,
the
reaction
and
table
below
show
Oxygen
Remember,
atoms
beatoms
created
or
destroyed
in
chemical
reactions,
We
can
fix
this
by
putting
in
1atoms,
more
Oxygen
molecule
on1inthe
left
By
the
number
you
can
see
that
the
chemical
Notice,
there
are
2cannot
Oxygen
on
left
side
and
3that
Oxygen
atoms
on
We
group
molecules
by
putting
coefficients
front
ofatom
them:
Thecounting
reaction
below
is together
notof
balanced
is
created
and
2and
Hydrogen
atoms
are
destroyed
they
can only
be
rearranged!
(reactant)
side
1 more
Water
molecule
on
theleft
right
(product)
side
the
right
side;
4byHydrogen
the
side
and 2 apart:
equation
is
balanced
andare
shows
the
actual
numbers
molecules
We can
see
it isalso
notthere
balanced
taking
theonreactants
&ofproducts
Therefore,
the
reaction
cannot
way!
total in
number
of
atoms
musthappen
be
thethis
same
on both
sides
of the
arrow
The
table
now
has
equal
number
of atoms
on
both
sides
of the
equation
Hydrogen
on
the
right
side
involved
this
reaction
CH4
O+2 +2 O2
CO2
H+2+O +2H2O
H
H CH
H
O O
O C O
H OH
O O
Left
Reactant Side
C=
O=
1
2
4
H=
4
9
7
6
9
Total Number of Atoms
Right
H OH
Product Side
O=
1
34
H=
42
C=
Balancing Chemical Reactions
••••• We
In
other
can
fixwords,
this
by
putting
reaction
and
more
table
Water
molecule
show
that
on
the
1front
Oxygen
left(reactant)
atom
By
counting
the
number
of
you
can
see
the
chemical
Remember,
atoms
cannot
be1atoms,
created
orbelow
destroyed
in
chemical
reactions,
group
molecules
byon
putting
coefficients
in
ofon
them:
Notice,
there
is
1the
Oxygen
atoms
left
side
and
2that
Oxygen
atoms
The
reaction
below
istogether
notin
balanced
is
created
and
1only
Hydrogen
molecule
on
the
side and
they
cansee
rearranged!
equation
ismore
balanced
andthe
shows
actual
numbers
atoms
the
right
side;
therefore
chemical
equation
is NOT of
balanced
• side
We
can
it be
is
NOT
balanced
bythe
taking
theright(product)
reactants
& products
•• The
Therefore,
table
thehas
reaction
equal
cannot
number
of
onway!
both
sides
of the
equation
The
total now
number
of
atoms
musthappen
beatoms
the this
same
on both
sides
of the
arrow
molecules
involved
in
this
reaction
apart:
2 H2
H2O + 2 H2O
H OH
H OH
Left
Reactant Side
O=
1
2
42
H=
H H
3
6
6
4
H H
O O
Right
Product Side
O=
2
24
H=
Total Number of Atoms
H+2 + O2
Subscripts and Coefficients
• When balancing chemical equations, it is important to note
that the subscripts can never change
• For example, in the equation below, the subscript of 4 in
methane cannot be changed, neither can the subscripts 2 in
Oxygen, Carbon dioxide and Water
CH4 + 2 O2
CO2 + 2H2O
• Only coefficients can be added by putting whole numbers in
front of the compounds when balancing chemical reactions
How Do we Balance Chemical Equations?
• By placing coefficients in front of each molecule
or compound
• Subscripts cannot be changed!
• Ex: CH4 + 2O2 CO2 + 2H2O
Balancing Chemical Equations
Remember: When balancing chemical equations, it is important to
note that the subscripts can never change!!!!
2
___O
___O
3
2
3
___
2 Mg + ___ O2
___
2 MgO
Practice:
Determine how many atoms of each element are in
each compound below:
1)
2)
3)
4)
2 Na + ___ Cl
___
2
4 Fe + ___
3 O
___
2
___
4 Al + ___
3 O2
2 Na + ___ F
___
2
2
___
NaCl
2 Fe O
___
2 3
___
2 Al2O3
2 NaF
___
Physical States
• In a reaction, we often use symbols to represent the physical state of
the reactants and products
• Look at the reaction below when sodium metal reacts with water:
Na(s) + H2O(l)
H2(g) + NaOH(aq)
• The symbol (s) tells us that Sodium (Na) is in the solid
state
• The symbol (l) tells us the water (H2O) is in the liquid
state
• The symbol (g) tells us the hydrogen (H2) is in the
gaseous state
• Finally, the symbol (aq) tells us that sodium hydroxide
(NaOH) is aqueous or dissolved in water
Symbol
State
(s)
solid
(l)
(g)
(aq)
liquid
gas
aqueous
What do the symbols represent in a
chemical equation?
• The symbols represent the physical state of the
reactants and products
Symbol
State
solid
Na(s) + H2O(l)
H2(g) + NaOH(aq) (s)
(l)
(g)
(aq)
liquid
gas
aqueous
or dissolved
in water
Summary
(you can always write your own summary)
• Explain the Law of Conservation of Mass in your own words
and apply it to chemical reactions:
• What is the difference between the reactants and products
in a chemical reaction?
• Describe the process of balancing chemical reactions, be
sure to explain how you count atoms on both sides of the
equation
• What can you not change when balancing chemical
reactions?
• Is the reaction below balanced? Explain why or why not:
K + Cl2 KCl
Slide 7
UNIT: Chemical Reactions
TOPIC: Properties of Reactions
Objectives: Lesson 1 of 3
•
•
•
•
To learn how we recognize a chemical reaction has took place
To learn what a chemical reactions is
To learn how we balance chemical equations
To learn the symbols for each physical state in a chemical
reaction
Quickwrite
In 1-2 sentences answer one of the questions below:
• What sort of clues do think indicate that a chemical reaction is
happening in your car engine????
• What sort of clues indicate a chemical reaction when you drop a
piece of alka selzter in water????
• What are some by products produced when your body breaks
down sugar, C6H12O6????? What are some clues that this
reaction is occuring in your body????? Hint: think of
temperature!!!!
Evidence for a Chemical Reaction
• How do you know a chemical reaction has occurred?
• Chemists look for visual clues such a color or heat
change, a solid forms, bubbles are produced, a flame
occurs
• However, reactions are not always visible
• Sometimes the only signal that a reaction is occurring is
a change in temperature as heat is produced
What are some clues that a
chemical reaction has occurred?
•
•
•
•
•
A color change
A solid forms
Bubbles form
A heat change
A flame is produced
Chemical Reactions
• Chemists have learned that a chemical change always involves a
rearrangement of the ways in which atoms are grouped and combine
with one another
• For example, consider the reaction that occurs with your laboratory
bunsen burners
• In this reaction, methane (CH4) reacts with oxygen (O2) in the air
• As you know, a flame is produce and heat is released
• As the atoms rearrange themselves, two new chemicals are produced
carbon dioxide (CO2), and water (H2O)
CH4 + O2
CO2 + H2O
Chemical
Reactions
Such a change is called a chemical reaction
•
• Notice, the atoms were rearranged, Oxygen combined with Carbon and
Hydrogen to produce 2 new chemicals: Water & Carbon Dioxide
• Chemical reactions obey the Law of Conservation of Matter which states: Atoms
cannot be destroyed, they can only be rearranged
CH4 + O2
CO2
Methane (CH4)
Water(H
Carbon
Dioxide
2O) (CO2)
Oxygen(O2)
H2O
What is a Chemical Reaction?
• A chemical reaction is the change that occurs when
atoms rearrange themselves and form new
compounds
• Chemical reactions obey the first LAW of
conservation of MASS or MATTER which states:
Atoms and matter cannot be created or destroyed,
they can only be rearranged
Chemical Equations
• We represent chemical reactions by writing a
chemical equation in which the chemicals
present before the reaction are on the left of
the arrow, and the chemicals formed by the
reaction are on the right of the arrow
• The arrow indicates the direction of the
change CH4 + O2
CO2 + H2O
Chemical Equations
• In the reaction of methane with oxygen, we have:
CH4 + O2
CO2 + H2O
Reactants
Products
• The chemicals present on the left side of the
equation are known as the reactants
• The chemicals present on the right side of the
equation are known as the products
What is a Chemical Equation?
• An equation that uses the formulas of chemicals
compounds and elements to show the reactants and
products in a chemical change
• Chemicals present before the reaction are on the left of
the arrow (reactants), and the chemicals formed by the
reaction are on the right of the arrow (products)
Ex: CH4 + O2
CO2 + H2O
Balancing Chemical Reactions
• It is important to realize that in a chemical
reaction, atoms are neither created nor
destroyed
• In other words, their must be the same
number of each type of atom on the product
side as on the reactant side of the arrow
••
•
•
•
Balancing Chemical Reactions
In
other
words,
the
reaction
and
table
below
show
Oxygen
Remember,
atoms
beatoms
created
or
destroyed
in
chemical
reactions,
We
can
fix
this
by
putting
in
1atoms,
more
Oxygen
molecule
on1inthe
left
By
the
number
you
can
see
that
the
chemical
Notice,
there
are
2cannot
Oxygen
on
left
side
and
3that
Oxygen
atoms
on
We
group
molecules
by
putting
coefficients
front
ofatom
them:
Thecounting
reaction
below
is together
notof
balanced
is
created
and
2and
Hydrogen
atoms
are
destroyed
they
can only
be
rearranged!
(reactant)
side
1 more
Water
molecule
on
theleft
right
(product)
side
the
right
side;
4byHydrogen
the
side
and 2 apart:
equation
is
balanced
andare
shows
the
actual
numbers
molecules
We can
see
it isalso
notthere
balanced
taking
theonreactants
&ofproducts
Therefore,
the
reaction
cannot
way!
total in
number
of
atoms
musthappen
be
thethis
same
on both
sides
of the
arrow
The
table
now
has
equal
number
of atoms
on
both
sides
of the
equation
Hydrogen
on
the
right
side
involved
this
reaction
CH4
O+2 +2 O2
CO2
H+2+O +2H2O
H
H CH
H
O O
O C O
H OH
O O
Left
Reactant Side
C=
O=
1
2
4
H=
4
9
7
6
9
Total Number of Atoms
Right
H OH
Product Side
O=
1
34
H=
42
C=
Balancing Chemical Reactions
••••• We
In
other
can
fixwords,
this
by
putting
reaction
and
more
table
Water
molecule
show
that
on
the
1front
Oxygen
left(reactant)
atom
By
counting
the
number
of
you
can
see
the
chemical
Remember,
atoms
cannot
be1atoms,
created
orbelow
destroyed
in
chemical
reactions,
group
molecules
byon
putting
coefficients
in
ofon
them:
Notice,
there
is
1the
Oxygen
atoms
left
side
and
2that
Oxygen
atoms
The
reaction
below
istogether
notin
balanced
is
created
and
1only
Hydrogen
molecule
on
the
side and
they
cansee
rearranged!
equation
ismore
balanced
andthe
shows
actual
numbers
atoms
the
right
side;
therefore
chemical
equation
is NOT of
balanced
• side
We
can
it be
is
NOT
balanced
bythe
taking
theright(product)
reactants
& products
•• The
Therefore,
table
thehas
reaction
equal
cannot
number
of
onway!
both
sides
of the
equation
The
total now
number
of
atoms
musthappen
beatoms
the this
same
on both
sides
of the
arrow
molecules
involved
in
this
reaction
apart:
2 H2
H2O + 2 H2O
H OH
H OH
Left
Reactant Side
O=
1
2
42
H=
H H
3
6
6
4
H H
O O
Right
Product Side
O=
2
24
H=
Total Number of Atoms
H+2 + O2
Subscripts and Coefficients
• When balancing chemical equations, it is important to note
that the subscripts can never change
• For example, in the equation below, the subscript of 4 in
methane cannot be changed, neither can the subscripts 2 in
Oxygen, Carbon dioxide and Water
CH4 + 2 O2
CO2 + 2H2O
• Only coefficients can be added by putting whole numbers in
front of the compounds when balancing chemical reactions
How Do we Balance Chemical Equations?
• By placing coefficients in front of each molecule
or compound
• Subscripts cannot be changed!
• Ex: CH4 + 2O2 CO2 + 2H2O
Balancing Chemical Equations
Remember: When balancing chemical equations, it is important to
note that the subscripts can never change!!!!
2
___O
___O
3
2
3
___
2 Mg + ___ O2
___
2 MgO
Practice:
Determine how many atoms of each element are in
each compound below:
1)
2)
3)
4)
2 Na + ___ Cl
___
2
4 Fe + ___
3 O
___
2
___
4 Al + ___
3 O2
2 Na + ___ F
___
2
2
___
NaCl
2 Fe O
___
2 3
___
2 Al2O3
2 NaF
___
Physical States
• In a reaction, we often use symbols to represent the physical state of
the reactants and products
• Look at the reaction below when sodium metal reacts with water:
Na(s) + H2O(l)
H2(g) + NaOH(aq)
• The symbol (s) tells us that Sodium (Na) is in the solid
state
• The symbol (l) tells us the water (H2O) is in the liquid
state
• The symbol (g) tells us the hydrogen (H2) is in the
gaseous state
• Finally, the symbol (aq) tells us that sodium hydroxide
(NaOH) is aqueous or dissolved in water
Symbol
State
(s)
solid
(l)
(g)
(aq)
liquid
gas
aqueous
What do the symbols represent in a
chemical equation?
• The symbols represent the physical state of the
reactants and products
Symbol
State
solid
Na(s) + H2O(l)
H2(g) + NaOH(aq) (s)
(l)
(g)
(aq)
liquid
gas
aqueous
or dissolved
in water
Summary
(you can always write your own summary)
• Explain the Law of Conservation of Mass in your own words
and apply it to chemical reactions:
• What is the difference between the reactants and products
in a chemical reaction?
• Describe the process of balancing chemical reactions, be
sure to explain how you count atoms on both sides of the
equation
• What can you not change when balancing chemical
reactions?
• Is the reaction below balanced? Explain why or why not:
K + Cl2 KCl
Slide 8
UNIT: Chemical Reactions
TOPIC: Properties of Reactions
Objectives: Lesson 1 of 3
•
•
•
•
To learn how we recognize a chemical reaction has took place
To learn what a chemical reactions is
To learn how we balance chemical equations
To learn the symbols for each physical state in a chemical
reaction
Quickwrite
In 1-2 sentences answer one of the questions below:
• What sort of clues do think indicate that a chemical reaction is
happening in your car engine????
• What sort of clues indicate a chemical reaction when you drop a
piece of alka selzter in water????
• What are some by products produced when your body breaks
down sugar, C6H12O6????? What are some clues that this
reaction is occuring in your body????? Hint: think of
temperature!!!!
Evidence for a Chemical Reaction
• How do you know a chemical reaction has occurred?
• Chemists look for visual clues such a color or heat
change, a solid forms, bubbles are produced, a flame
occurs
• However, reactions are not always visible
• Sometimes the only signal that a reaction is occurring is
a change in temperature as heat is produced
What are some clues that a
chemical reaction has occurred?
•
•
•
•
•
A color change
A solid forms
Bubbles form
A heat change
A flame is produced
Chemical Reactions
• Chemists have learned that a chemical change always involves a
rearrangement of the ways in which atoms are grouped and combine
with one another
• For example, consider the reaction that occurs with your laboratory
bunsen burners
• In this reaction, methane (CH4) reacts with oxygen (O2) in the air
• As you know, a flame is produce and heat is released
• As the atoms rearrange themselves, two new chemicals are produced
carbon dioxide (CO2), and water (H2O)
CH4 + O2
CO2 + H2O
Chemical
Reactions
Such a change is called a chemical reaction
•
• Notice, the atoms were rearranged, Oxygen combined with Carbon and
Hydrogen to produce 2 new chemicals: Water & Carbon Dioxide
• Chemical reactions obey the Law of Conservation of Matter which states: Atoms
cannot be destroyed, they can only be rearranged
CH4 + O2
CO2
Methane (CH4)
Water(H
Carbon
Dioxide
2O) (CO2)
Oxygen(O2)
H2O
What is a Chemical Reaction?
• A chemical reaction is the change that occurs when
atoms rearrange themselves and form new
compounds
• Chemical reactions obey the first LAW of
conservation of MASS or MATTER which states:
Atoms and matter cannot be created or destroyed,
they can only be rearranged
Chemical Equations
• We represent chemical reactions by writing a
chemical equation in which the chemicals
present before the reaction are on the left of
the arrow, and the chemicals formed by the
reaction are on the right of the arrow
• The arrow indicates the direction of the
change CH4 + O2
CO2 + H2O
Chemical Equations
• In the reaction of methane with oxygen, we have:
CH4 + O2
CO2 + H2O
Reactants
Products
• The chemicals present on the left side of the
equation are known as the reactants
• The chemicals present on the right side of the
equation are known as the products
What is a Chemical Equation?
• An equation that uses the formulas of chemicals
compounds and elements to show the reactants and
products in a chemical change
• Chemicals present before the reaction are on the left of
the arrow (reactants), and the chemicals formed by the
reaction are on the right of the arrow (products)
Ex: CH4 + O2
CO2 + H2O
Balancing Chemical Reactions
• It is important to realize that in a chemical
reaction, atoms are neither created nor
destroyed
• In other words, their must be the same
number of each type of atom on the product
side as on the reactant side of the arrow
••
•
•
•
Balancing Chemical Reactions
In
other
words,
the
reaction
and
table
below
show
Oxygen
Remember,
atoms
beatoms
created
or
destroyed
in
chemical
reactions,
We
can
fix
this
by
putting
in
1atoms,
more
Oxygen
molecule
on1inthe
left
By
the
number
you
can
see
that
the
chemical
Notice,
there
are
2cannot
Oxygen
on
left
side
and
3that
Oxygen
atoms
on
We
group
molecules
by
putting
coefficients
front
ofatom
them:
Thecounting
reaction
below
is together
notof
balanced
is
created
and
2and
Hydrogen
atoms
are
destroyed
they
can only
be
rearranged!
(reactant)
side
1 more
Water
molecule
on
theleft
right
(product)
side
the
right
side;
4byHydrogen
the
side
and 2 apart:
equation
is
balanced
andare
shows
the
actual
numbers
molecules
We can
see
it isalso
notthere
balanced
taking
theonreactants
&ofproducts
Therefore,
the
reaction
cannot
way!
total in
number
of
atoms
musthappen
be
thethis
same
on both
sides
of the
arrow
The
table
now
has
equal
number
of atoms
on
both
sides
of the
equation
Hydrogen
on
the
right
side
involved
this
reaction
CH4
O+2 +2 O2
CO2
H+2+O +2H2O
H
H CH
H
O O
O C O
H OH
O O
Left
Reactant Side
C=
O=
1
2
4
H=
4
9
7
6
9
Total Number of Atoms
Right
H OH
Product Side
O=
1
34
H=
42
C=
Balancing Chemical Reactions
••••• We
In
other
can
fixwords,
this
by
putting
reaction
and
more
table
Water
molecule
show
that
on
the
1front
Oxygen
left(reactant)
atom
By
counting
the
number
of
you
can
see
the
chemical
Remember,
atoms
cannot
be1atoms,
created
orbelow
destroyed
in
chemical
reactions,
group
molecules
byon
putting
coefficients
in
ofon
them:
Notice,
there
is
1the
Oxygen
atoms
left
side
and
2that
Oxygen
atoms
The
reaction
below
istogether
notin
balanced
is
created
and
1only
Hydrogen
molecule
on
the
side and
they
cansee
rearranged!
equation
ismore
balanced
andthe
shows
actual
numbers
atoms
the
right
side;
therefore
chemical
equation
is NOT of
balanced
• side
We
can
it be
is
NOT
balanced
bythe
taking
theright(product)
reactants
& products
•• The
Therefore,
table
thehas
reaction
equal
cannot
number
of
onway!
both
sides
of the
equation
The
total now
number
of
atoms
musthappen
beatoms
the this
same
on both
sides
of the
arrow
molecules
involved
in
this
reaction
apart:
2 H2
H2O + 2 H2O
H OH
H OH
Left
Reactant Side
O=
1
2
42
H=
H H
3
6
6
4
H H
O O
Right
Product Side
O=
2
24
H=
Total Number of Atoms
H+2 + O2
Subscripts and Coefficients
• When balancing chemical equations, it is important to note
that the subscripts can never change
• For example, in the equation below, the subscript of 4 in
methane cannot be changed, neither can the subscripts 2 in
Oxygen, Carbon dioxide and Water
CH4 + 2 O2
CO2 + 2H2O
• Only coefficients can be added by putting whole numbers in
front of the compounds when balancing chemical reactions
How Do we Balance Chemical Equations?
• By placing coefficients in front of each molecule
or compound
• Subscripts cannot be changed!
• Ex: CH4 + 2O2 CO2 + 2H2O
Balancing Chemical Equations
Remember: When balancing chemical equations, it is important to
note that the subscripts can never change!!!!
2
___O
___O
3
2
3
___
2 Mg + ___ O2
___
2 MgO
Practice:
Determine how many atoms of each element are in
each compound below:
1)
2)
3)
4)
2 Na + ___ Cl
___
2
4 Fe + ___
3 O
___
2
___
4 Al + ___
3 O2
2 Na + ___ F
___
2
2
___
NaCl
2 Fe O
___
2 3
___
2 Al2O3
2 NaF
___
Physical States
• In a reaction, we often use symbols to represent the physical state of
the reactants and products
• Look at the reaction below when sodium metal reacts with water:
Na(s) + H2O(l)
H2(g) + NaOH(aq)
• The symbol (s) tells us that Sodium (Na) is in the solid
state
• The symbol (l) tells us the water (H2O) is in the liquid
state
• The symbol (g) tells us the hydrogen (H2) is in the
gaseous state
• Finally, the symbol (aq) tells us that sodium hydroxide
(NaOH) is aqueous or dissolved in water
Symbol
State
(s)
solid
(l)
(g)
(aq)
liquid
gas
aqueous
What do the symbols represent in a
chemical equation?
• The symbols represent the physical state of the
reactants and products
Symbol
State
solid
Na(s) + H2O(l)
H2(g) + NaOH(aq) (s)
(l)
(g)
(aq)
liquid
gas
aqueous
or dissolved
in water
Summary
(you can always write your own summary)
• Explain the Law of Conservation of Mass in your own words
and apply it to chemical reactions:
• What is the difference between the reactants and products
in a chemical reaction?
• Describe the process of balancing chemical reactions, be
sure to explain how you count atoms on both sides of the
equation
• What can you not change when balancing chemical
reactions?
• Is the reaction below balanced? Explain why or why not:
K + Cl2 KCl
Slide 9
UNIT: Chemical Reactions
TOPIC: Properties of Reactions
Objectives: Lesson 1 of 3
•
•
•
•
To learn how we recognize a chemical reaction has took place
To learn what a chemical reactions is
To learn how we balance chemical equations
To learn the symbols for each physical state in a chemical
reaction
Quickwrite
In 1-2 sentences answer one of the questions below:
• What sort of clues do think indicate that a chemical reaction is
happening in your car engine????
• What sort of clues indicate a chemical reaction when you drop a
piece of alka selzter in water????
• What are some by products produced when your body breaks
down sugar, C6H12O6????? What are some clues that this
reaction is occuring in your body????? Hint: think of
temperature!!!!
Evidence for a Chemical Reaction
• How do you know a chemical reaction has occurred?
• Chemists look for visual clues such a color or heat
change, a solid forms, bubbles are produced, a flame
occurs
• However, reactions are not always visible
• Sometimes the only signal that a reaction is occurring is
a change in temperature as heat is produced
What are some clues that a
chemical reaction has occurred?
•
•
•
•
•
A color change
A solid forms
Bubbles form
A heat change
A flame is produced
Chemical Reactions
• Chemists have learned that a chemical change always involves a
rearrangement of the ways in which atoms are grouped and combine
with one another
• For example, consider the reaction that occurs with your laboratory
bunsen burners
• In this reaction, methane (CH4) reacts with oxygen (O2) in the air
• As you know, a flame is produce and heat is released
• As the atoms rearrange themselves, two new chemicals are produced
carbon dioxide (CO2), and water (H2O)
CH4 + O2
CO2 + H2O
Chemical
Reactions
Such a change is called a chemical reaction
•
• Notice, the atoms were rearranged, Oxygen combined with Carbon and
Hydrogen to produce 2 new chemicals: Water & Carbon Dioxide
• Chemical reactions obey the Law of Conservation of Matter which states: Atoms
cannot be destroyed, they can only be rearranged
CH4 + O2
CO2
Methane (CH4)
Water(H
Carbon
Dioxide
2O) (CO2)
Oxygen(O2)
H2O
What is a Chemical Reaction?
• A chemical reaction is the change that occurs when
atoms rearrange themselves and form new
compounds
• Chemical reactions obey the first LAW of
conservation of MASS or MATTER which states:
Atoms and matter cannot be created or destroyed,
they can only be rearranged
Chemical Equations
• We represent chemical reactions by writing a
chemical equation in which the chemicals
present before the reaction are on the left of
the arrow, and the chemicals formed by the
reaction are on the right of the arrow
• The arrow indicates the direction of the
change CH4 + O2
CO2 + H2O
Chemical Equations
• In the reaction of methane with oxygen, we have:
CH4 + O2
CO2 + H2O
Reactants
Products
• The chemicals present on the left side of the
equation are known as the reactants
• The chemicals present on the right side of the
equation are known as the products
What is a Chemical Equation?
• An equation that uses the formulas of chemicals
compounds and elements to show the reactants and
products in a chemical change
• Chemicals present before the reaction are on the left of
the arrow (reactants), and the chemicals formed by the
reaction are on the right of the arrow (products)
Ex: CH4 + O2
CO2 + H2O
Balancing Chemical Reactions
• It is important to realize that in a chemical
reaction, atoms are neither created nor
destroyed
• In other words, their must be the same
number of each type of atom on the product
side as on the reactant side of the arrow
••
•
•
•
Balancing Chemical Reactions
In
other
words,
the
reaction
and
table
below
show
Oxygen
Remember,
atoms
beatoms
created
or
destroyed
in
chemical
reactions,
We
can
fix
this
by
putting
in
1atoms,
more
Oxygen
molecule
on1inthe
left
By
the
number
you
can
see
that
the
chemical
Notice,
there
are
2cannot
Oxygen
on
left
side
and
3that
Oxygen
atoms
on
We
group
molecules
by
putting
coefficients
front
ofatom
them:
Thecounting
reaction
below
is together
notof
balanced
is
created
and
2and
Hydrogen
atoms
are
destroyed
they
can only
be
rearranged!
(reactant)
side
1 more
Water
molecule
on
theleft
right
(product)
side
the
right
side;
4byHydrogen
the
side
and 2 apart:
equation
is
balanced
andare
shows
the
actual
numbers
molecules
We can
see
it isalso
notthere
balanced
taking
theonreactants
&ofproducts
Therefore,
the
reaction
cannot
way!
total in
number
of
atoms
musthappen
be
thethis
same
on both
sides
of the
arrow
The
table
now
has
equal
number
of atoms
on
both
sides
of the
equation
Hydrogen
on
the
right
side
involved
this
reaction
CH4
O+2 +2 O2
CO2
H+2+O +2H2O
H
H CH
H
O O
O C O
H OH
O O
Left
Reactant Side
C=
O=
1
2
4
H=
4
9
7
6
9
Total Number of Atoms
Right
H OH
Product Side
O=
1
34
H=
42
C=
Balancing Chemical Reactions
••••• We
In
other
can
fixwords,
this
by
putting
reaction
and
more
table
Water
molecule
show
that
on
the
1front
Oxygen
left(reactant)
atom
By
counting
the
number
of
you
can
see
the
chemical
Remember,
atoms
cannot
be1atoms,
created
orbelow
destroyed
in
chemical
reactions,
group
molecules
byon
putting
coefficients
in
ofon
them:
Notice,
there
is
1the
Oxygen
atoms
left
side
and
2that
Oxygen
atoms
The
reaction
below
istogether
notin
balanced
is
created
and
1only
Hydrogen
molecule
on
the
side and
they
cansee
rearranged!
equation
ismore
balanced
andthe
shows
actual
numbers
atoms
the
right
side;
therefore
chemical
equation
is NOT of
balanced
• side
We
can
it be
is
NOT
balanced
bythe
taking
theright(product)
reactants
& products
•• The
Therefore,
table
thehas
reaction
equal
cannot
number
of
onway!
both
sides
of the
equation
The
total now
number
of
atoms
musthappen
beatoms
the this
same
on both
sides
of the
arrow
molecules
involved
in
this
reaction
apart:
2 H2
H2O + 2 H2O
H OH
H OH
Left
Reactant Side
O=
1
2
42
H=
H H
3
6
6
4
H H
O O
Right
Product Side
O=
2
24
H=
Total Number of Atoms
H+2 + O2
Subscripts and Coefficients
• When balancing chemical equations, it is important to note
that the subscripts can never change
• For example, in the equation below, the subscript of 4 in
methane cannot be changed, neither can the subscripts 2 in
Oxygen, Carbon dioxide and Water
CH4 + 2 O2
CO2 + 2H2O
• Only coefficients can be added by putting whole numbers in
front of the compounds when balancing chemical reactions
How Do we Balance Chemical Equations?
• By placing coefficients in front of each molecule
or compound
• Subscripts cannot be changed!
• Ex: CH4 + 2O2 CO2 + 2H2O
Balancing Chemical Equations
Remember: When balancing chemical equations, it is important to
note that the subscripts can never change!!!!
2
___O
___O
3
2
3
___
2 Mg + ___ O2
___
2 MgO
Practice:
Determine how many atoms of each element are in
each compound below:
1)
2)
3)
4)
2 Na + ___ Cl
___
2
4 Fe + ___
3 O
___
2
___
4 Al + ___
3 O2
2 Na + ___ F
___
2
2
___
NaCl
2 Fe O
___
2 3
___
2 Al2O3
2 NaF
___
Physical States
• In a reaction, we often use symbols to represent the physical state of
the reactants and products
• Look at the reaction below when sodium metal reacts with water:
Na(s) + H2O(l)
H2(g) + NaOH(aq)
• The symbol (s) tells us that Sodium (Na) is in the solid
state
• The symbol (l) tells us the water (H2O) is in the liquid
state
• The symbol (g) tells us the hydrogen (H2) is in the
gaseous state
• Finally, the symbol (aq) tells us that sodium hydroxide
(NaOH) is aqueous or dissolved in water
Symbol
State
(s)
solid
(l)
(g)
(aq)
liquid
gas
aqueous
What do the symbols represent in a
chemical equation?
• The symbols represent the physical state of the
reactants and products
Symbol
State
solid
Na(s) + H2O(l)
H2(g) + NaOH(aq) (s)
(l)
(g)
(aq)
liquid
gas
aqueous
or dissolved
in water
Summary
(you can always write your own summary)
• Explain the Law of Conservation of Mass in your own words
and apply it to chemical reactions:
• What is the difference between the reactants and products
in a chemical reaction?
• Describe the process of balancing chemical reactions, be
sure to explain how you count atoms on both sides of the
equation
• What can you not change when balancing chemical
reactions?
• Is the reaction below balanced? Explain why or why not:
K + Cl2 KCl
Slide 10
UNIT: Chemical Reactions
TOPIC: Properties of Reactions
Objectives: Lesson 1 of 3
•
•
•
•
To learn how we recognize a chemical reaction has took place
To learn what a chemical reactions is
To learn how we balance chemical equations
To learn the symbols for each physical state in a chemical
reaction
Quickwrite
In 1-2 sentences answer one of the questions below:
• What sort of clues do think indicate that a chemical reaction is
happening in your car engine????
• What sort of clues indicate a chemical reaction when you drop a
piece of alka selzter in water????
• What are some by products produced when your body breaks
down sugar, C6H12O6????? What are some clues that this
reaction is occuring in your body????? Hint: think of
temperature!!!!
Evidence for a Chemical Reaction
• How do you know a chemical reaction has occurred?
• Chemists look for visual clues such a color or heat
change, a solid forms, bubbles are produced, a flame
occurs
• However, reactions are not always visible
• Sometimes the only signal that a reaction is occurring is
a change in temperature as heat is produced
What are some clues that a
chemical reaction has occurred?
•
•
•
•
•
A color change
A solid forms
Bubbles form
A heat change
A flame is produced
Chemical Reactions
• Chemists have learned that a chemical change always involves a
rearrangement of the ways in which atoms are grouped and combine
with one another
• For example, consider the reaction that occurs with your laboratory
bunsen burners
• In this reaction, methane (CH4) reacts with oxygen (O2) in the air
• As you know, a flame is produce and heat is released
• As the atoms rearrange themselves, two new chemicals are produced
carbon dioxide (CO2), and water (H2O)
CH4 + O2
CO2 + H2O
Chemical
Reactions
Such a change is called a chemical reaction
•
• Notice, the atoms were rearranged, Oxygen combined with Carbon and
Hydrogen to produce 2 new chemicals: Water & Carbon Dioxide
• Chemical reactions obey the Law of Conservation of Matter which states: Atoms
cannot be destroyed, they can only be rearranged
CH4 + O2
CO2
Methane (CH4)
Water(H
Carbon
Dioxide
2O) (CO2)
Oxygen(O2)
H2O
What is a Chemical Reaction?
• A chemical reaction is the change that occurs when
atoms rearrange themselves and form new
compounds
• Chemical reactions obey the first LAW of
conservation of MASS or MATTER which states:
Atoms and matter cannot be created or destroyed,
they can only be rearranged
Chemical Equations
• We represent chemical reactions by writing a
chemical equation in which the chemicals
present before the reaction are on the left of
the arrow, and the chemicals formed by the
reaction are on the right of the arrow
• The arrow indicates the direction of the
change CH4 + O2
CO2 + H2O
Chemical Equations
• In the reaction of methane with oxygen, we have:
CH4 + O2
CO2 + H2O
Reactants
Products
• The chemicals present on the left side of the
equation are known as the reactants
• The chemicals present on the right side of the
equation are known as the products
What is a Chemical Equation?
• An equation that uses the formulas of chemicals
compounds and elements to show the reactants and
products in a chemical change
• Chemicals present before the reaction are on the left of
the arrow (reactants), and the chemicals formed by the
reaction are on the right of the arrow (products)
Ex: CH4 + O2
CO2 + H2O
Balancing Chemical Reactions
• It is important to realize that in a chemical
reaction, atoms are neither created nor
destroyed
• In other words, their must be the same
number of each type of atom on the product
side as on the reactant side of the arrow
••
•
•
•
Balancing Chemical Reactions
In
other
words,
the
reaction
and
table
below
show
Oxygen
Remember,
atoms
beatoms
created
or
destroyed
in
chemical
reactions,
We
can
fix
this
by
putting
in
1atoms,
more
Oxygen
molecule
on1inthe
left
By
the
number
you
can
see
that
the
chemical
Notice,
there
are
2cannot
Oxygen
on
left
side
and
3that
Oxygen
atoms
on
We
group
molecules
by
putting
coefficients
front
ofatom
them:
Thecounting
reaction
below
is together
notof
balanced
is
created
and
2and
Hydrogen
atoms
are
destroyed
they
can only
be
rearranged!
(reactant)
side
1 more
Water
molecule
on
theleft
right
(product)
side
the
right
side;
4byHydrogen
the
side
and 2 apart:
equation
is
balanced
andare
shows
the
actual
numbers
molecules
We can
see
it isalso
notthere
balanced
taking
theonreactants
&ofproducts
Therefore,
the
reaction
cannot
way!
total in
number
of
atoms
musthappen
be
thethis
same
on both
sides
of the
arrow
The
table
now
has
equal
number
of atoms
on
both
sides
of the
equation
Hydrogen
on
the
right
side
involved
this
reaction
CH4
O+2 +2 O2
CO2
H+2+O +2H2O
H
H CH
H
O O
O C O
H OH
O O
Left
Reactant Side
C=
O=
1
2
4
H=
4
9
7
6
9
Total Number of Atoms
Right
H OH
Product Side
O=
1
34
H=
42
C=
Balancing Chemical Reactions
••••• We
In
other
can
fixwords,
this
by
putting
reaction
and
more
table
Water
molecule
show
that
on
the
1front
Oxygen
left(reactant)
atom
By
counting
the
number
of
you
can
see
the
chemical
Remember,
atoms
cannot
be1atoms,
created
orbelow
destroyed
in
chemical
reactions,
group
molecules
byon
putting
coefficients
in
ofon
them:
Notice,
there
is
1the
Oxygen
atoms
left
side
and
2that
Oxygen
atoms
The
reaction
below
istogether
notin
balanced
is
created
and
1only
Hydrogen
molecule
on
the
side and
they
cansee
rearranged!
equation
ismore
balanced
andthe
shows
actual
numbers
atoms
the
right
side;
therefore
chemical
equation
is NOT of
balanced
• side
We
can
it be
is
NOT
balanced
bythe
taking
theright(product)
reactants
& products
•• The
Therefore,
table
thehas
reaction
equal
cannot
number
of
onway!
both
sides
of the
equation
The
total now
number
of
atoms
musthappen
beatoms
the this
same
on both
sides
of the
arrow
molecules
involved
in
this
reaction
apart:
2 H2
H2O + 2 H2O
H OH
H OH
Left
Reactant Side
O=
1
2
42
H=
H H
3
6
6
4
H H
O O
Right
Product Side
O=
2
24
H=
Total Number of Atoms
H+2 + O2
Subscripts and Coefficients
• When balancing chemical equations, it is important to note
that the subscripts can never change
• For example, in the equation below, the subscript of 4 in
methane cannot be changed, neither can the subscripts 2 in
Oxygen, Carbon dioxide and Water
CH4 + 2 O2
CO2 + 2H2O
• Only coefficients can be added by putting whole numbers in
front of the compounds when balancing chemical reactions
How Do we Balance Chemical Equations?
• By placing coefficients in front of each molecule
or compound
• Subscripts cannot be changed!
• Ex: CH4 + 2O2 CO2 + 2H2O
Balancing Chemical Equations
Remember: When balancing chemical equations, it is important to
note that the subscripts can never change!!!!
2
___O
___O
3
2
3
___
2 Mg + ___ O2
___
2 MgO
Practice:
Determine how many atoms of each element are in
each compound below:
1)
2)
3)
4)
2 Na + ___ Cl
___
2
4 Fe + ___
3 O
___
2
___
4 Al + ___
3 O2
2 Na + ___ F
___
2
2
___
NaCl
2 Fe O
___
2 3
___
2 Al2O3
2 NaF
___
Physical States
• In a reaction, we often use symbols to represent the physical state of
the reactants and products
• Look at the reaction below when sodium metal reacts with water:
Na(s) + H2O(l)
H2(g) + NaOH(aq)
• The symbol (s) tells us that Sodium (Na) is in the solid
state
• The symbol (l) tells us the water (H2O) is in the liquid
state
• The symbol (g) tells us the hydrogen (H2) is in the
gaseous state
• Finally, the symbol (aq) tells us that sodium hydroxide
(NaOH) is aqueous or dissolved in water
Symbol
State
(s)
solid
(l)
(g)
(aq)
liquid
gas
aqueous
What do the symbols represent in a
chemical equation?
• The symbols represent the physical state of the
reactants and products
Symbol
State
solid
Na(s) + H2O(l)
H2(g) + NaOH(aq) (s)
(l)
(g)
(aq)
liquid
gas
aqueous
or dissolved
in water
Summary
(you can always write your own summary)
• Explain the Law of Conservation of Mass in your own words
and apply it to chemical reactions:
• What is the difference between the reactants and products
in a chemical reaction?
• Describe the process of balancing chemical reactions, be
sure to explain how you count atoms on both sides of the
equation
• What can you not change when balancing chemical
reactions?
• Is the reaction below balanced? Explain why or why not:
K + Cl2 KCl
Slide 11
UNIT: Chemical Reactions
TOPIC: Properties of Reactions
Objectives: Lesson 1 of 3
•
•
•
•
To learn how we recognize a chemical reaction has took place
To learn what a chemical reactions is
To learn how we balance chemical equations
To learn the symbols for each physical state in a chemical
reaction
Quickwrite
In 1-2 sentences answer one of the questions below:
• What sort of clues do think indicate that a chemical reaction is
happening in your car engine????
• What sort of clues indicate a chemical reaction when you drop a
piece of alka selzter in water????
• What are some by products produced when your body breaks
down sugar, C6H12O6????? What are some clues that this
reaction is occuring in your body????? Hint: think of
temperature!!!!
Evidence for a Chemical Reaction
• How do you know a chemical reaction has occurred?
• Chemists look for visual clues such a color or heat
change, a solid forms, bubbles are produced, a flame
occurs
• However, reactions are not always visible
• Sometimes the only signal that a reaction is occurring is
a change in temperature as heat is produced
What are some clues that a
chemical reaction has occurred?
•
•
•
•
•
A color change
A solid forms
Bubbles form
A heat change
A flame is produced
Chemical Reactions
• Chemists have learned that a chemical change always involves a
rearrangement of the ways in which atoms are grouped and combine
with one another
• For example, consider the reaction that occurs with your laboratory
bunsen burners
• In this reaction, methane (CH4) reacts with oxygen (O2) in the air
• As you know, a flame is produce and heat is released
• As the atoms rearrange themselves, two new chemicals are produced
carbon dioxide (CO2), and water (H2O)
CH4 + O2
CO2 + H2O
Chemical
Reactions
Such a change is called a chemical reaction
•
• Notice, the atoms were rearranged, Oxygen combined with Carbon and
Hydrogen to produce 2 new chemicals: Water & Carbon Dioxide
• Chemical reactions obey the Law of Conservation of Matter which states: Atoms
cannot be destroyed, they can only be rearranged
CH4 + O2
CO2
Methane (CH4)
Water(H
Carbon
Dioxide
2O) (CO2)
Oxygen(O2)
H2O
What is a Chemical Reaction?
• A chemical reaction is the change that occurs when
atoms rearrange themselves and form new
compounds
• Chemical reactions obey the first LAW of
conservation of MASS or MATTER which states:
Atoms and matter cannot be created or destroyed,
they can only be rearranged
Chemical Equations
• We represent chemical reactions by writing a
chemical equation in which the chemicals
present before the reaction are on the left of
the arrow, and the chemicals formed by the
reaction are on the right of the arrow
• The arrow indicates the direction of the
change CH4 + O2
CO2 + H2O
Chemical Equations
• In the reaction of methane with oxygen, we have:
CH4 + O2
CO2 + H2O
Reactants
Products
• The chemicals present on the left side of the
equation are known as the reactants
• The chemicals present on the right side of the
equation are known as the products
What is a Chemical Equation?
• An equation that uses the formulas of chemicals
compounds and elements to show the reactants and
products in a chemical change
• Chemicals present before the reaction are on the left of
the arrow (reactants), and the chemicals formed by the
reaction are on the right of the arrow (products)
Ex: CH4 + O2
CO2 + H2O
Balancing Chemical Reactions
• It is important to realize that in a chemical
reaction, atoms are neither created nor
destroyed
• In other words, their must be the same
number of each type of atom on the product
side as on the reactant side of the arrow
••
•
•
•
Balancing Chemical Reactions
In
other
words,
the
reaction
and
table
below
show
Oxygen
Remember,
atoms
beatoms
created
or
destroyed
in
chemical
reactions,
We
can
fix
this
by
putting
in
1atoms,
more
Oxygen
molecule
on1inthe
left
By
the
number
you
can
see
that
the
chemical
Notice,
there
are
2cannot
Oxygen
on
left
side
and
3that
Oxygen
atoms
on
We
group
molecules
by
putting
coefficients
front
ofatom
them:
Thecounting
reaction
below
is together
notof
balanced
is
created
and
2and
Hydrogen
atoms
are
destroyed
they
can only
be
rearranged!
(reactant)
side
1 more
Water
molecule
on
theleft
right
(product)
side
the
right
side;
4byHydrogen
the
side
and 2 apart:
equation
is
balanced
andare
shows
the
actual
numbers
molecules
We can
see
it isalso
notthere
balanced
taking
theonreactants
&ofproducts
Therefore,
the
reaction
cannot
way!
total in
number
of
atoms
musthappen
be
thethis
same
on both
sides
of the
arrow
The
table
now
has
equal
number
of atoms
on
both
sides
of the
equation
Hydrogen
on
the
right
side
involved
this
reaction
CH4
O+2 +2 O2
CO2
H+2+O +2H2O
H
H CH
H
O O
O C O
H OH
O O
Left
Reactant Side
C=
O=
1
2
4
H=
4
9
7
6
9
Total Number of Atoms
Right
H OH
Product Side
O=
1
34
H=
42
C=
Balancing Chemical Reactions
••••• We
In
other
can
fixwords,
this
by
putting
reaction
and
more
table
Water
molecule
show
that
on
the
1front
Oxygen
left(reactant)
atom
By
counting
the
number
of
you
can
see
the
chemical
Remember,
atoms
cannot
be1atoms,
created
orbelow
destroyed
in
chemical
reactions,
group
molecules
byon
putting
coefficients
in
ofon
them:
Notice,
there
is
1the
Oxygen
atoms
left
side
and
2that
Oxygen
atoms
The
reaction
below
istogether
notin
balanced
is
created
and
1only
Hydrogen
molecule
on
the
side and
they
cansee
rearranged!
equation
ismore
balanced
andthe
shows
actual
numbers
atoms
the
right
side;
therefore
chemical
equation
is NOT of
balanced
• side
We
can
it be
is
NOT
balanced
bythe
taking
theright(product)
reactants
& products
•• The
Therefore,
table
thehas
reaction
equal
cannot
number
of
onway!
both
sides
of the
equation
The
total now
number
of
atoms
musthappen
beatoms
the this
same
on both
sides
of the
arrow
molecules
involved
in
this
reaction
apart:
2 H2
H2O + 2 H2O
H OH
H OH
Left
Reactant Side
O=
1
2
42
H=
H H
3
6
6
4
H H
O O
Right
Product Side
O=
2
24
H=
Total Number of Atoms
H+2 + O2
Subscripts and Coefficients
• When balancing chemical equations, it is important to note
that the subscripts can never change
• For example, in the equation below, the subscript of 4 in
methane cannot be changed, neither can the subscripts 2 in
Oxygen, Carbon dioxide and Water
CH4 + 2 O2
CO2 + 2H2O
• Only coefficients can be added by putting whole numbers in
front of the compounds when balancing chemical reactions
How Do we Balance Chemical Equations?
• By placing coefficients in front of each molecule
or compound
• Subscripts cannot be changed!
• Ex: CH4 + 2O2 CO2 + 2H2O
Balancing Chemical Equations
Remember: When balancing chemical equations, it is important to
note that the subscripts can never change!!!!
2
___O
___O
3
2
3
___
2 Mg + ___ O2
___
2 MgO
Practice:
Determine how many atoms of each element are in
each compound below:
1)
2)
3)
4)
2 Na + ___ Cl
___
2
4 Fe + ___
3 O
___
2
___
4 Al + ___
3 O2
2 Na + ___ F
___
2
2
___
NaCl
2 Fe O
___
2 3
___
2 Al2O3
2 NaF
___
Physical States
• In a reaction, we often use symbols to represent the physical state of
the reactants and products
• Look at the reaction below when sodium metal reacts with water:
Na(s) + H2O(l)
H2(g) + NaOH(aq)
• The symbol (s) tells us that Sodium (Na) is in the solid
state
• The symbol (l) tells us the water (H2O) is in the liquid
state
• The symbol (g) tells us the hydrogen (H2) is in the
gaseous state
• Finally, the symbol (aq) tells us that sodium hydroxide
(NaOH) is aqueous or dissolved in water
Symbol
State
(s)
solid
(l)
(g)
(aq)
liquid
gas
aqueous
What do the symbols represent in a
chemical equation?
• The symbols represent the physical state of the
reactants and products
Symbol
State
solid
Na(s) + H2O(l)
H2(g) + NaOH(aq) (s)
(l)
(g)
(aq)
liquid
gas
aqueous
or dissolved
in water
Summary
(you can always write your own summary)
• Explain the Law of Conservation of Mass in your own words
and apply it to chemical reactions:
• What is the difference between the reactants and products
in a chemical reaction?
• Describe the process of balancing chemical reactions, be
sure to explain how you count atoms on both sides of the
equation
• What can you not change when balancing chemical
reactions?
• Is the reaction below balanced? Explain why or why not:
K + Cl2 KCl
Slide 12
UNIT: Chemical Reactions
TOPIC: Properties of Reactions
Objectives: Lesson 1 of 3
•
•
•
•
To learn how we recognize a chemical reaction has took place
To learn what a chemical reactions is
To learn how we balance chemical equations
To learn the symbols for each physical state in a chemical
reaction
Quickwrite
In 1-2 sentences answer one of the questions below:
• What sort of clues do think indicate that a chemical reaction is
happening in your car engine????
• What sort of clues indicate a chemical reaction when you drop a
piece of alka selzter in water????
• What are some by products produced when your body breaks
down sugar, C6H12O6????? What are some clues that this
reaction is occuring in your body????? Hint: think of
temperature!!!!
Evidence for a Chemical Reaction
• How do you know a chemical reaction has occurred?
• Chemists look for visual clues such a color or heat
change, a solid forms, bubbles are produced, a flame
occurs
• However, reactions are not always visible
• Sometimes the only signal that a reaction is occurring is
a change in temperature as heat is produced
What are some clues that a
chemical reaction has occurred?
•
•
•
•
•
A color change
A solid forms
Bubbles form
A heat change
A flame is produced
Chemical Reactions
• Chemists have learned that a chemical change always involves a
rearrangement of the ways in which atoms are grouped and combine
with one another
• For example, consider the reaction that occurs with your laboratory
bunsen burners
• In this reaction, methane (CH4) reacts with oxygen (O2) in the air
• As you know, a flame is produce and heat is released
• As the atoms rearrange themselves, two new chemicals are produced
carbon dioxide (CO2), and water (H2O)
CH4 + O2
CO2 + H2O
Chemical
Reactions
Such a change is called a chemical reaction
•
• Notice, the atoms were rearranged, Oxygen combined with Carbon and
Hydrogen to produce 2 new chemicals: Water & Carbon Dioxide
• Chemical reactions obey the Law of Conservation of Matter which states: Atoms
cannot be destroyed, they can only be rearranged
CH4 + O2
CO2
Methane (CH4)
Water(H
Carbon
Dioxide
2O) (CO2)
Oxygen(O2)
H2O
What is a Chemical Reaction?
• A chemical reaction is the change that occurs when
atoms rearrange themselves and form new
compounds
• Chemical reactions obey the first LAW of
conservation of MASS or MATTER which states:
Atoms and matter cannot be created or destroyed,
they can only be rearranged
Chemical Equations
• We represent chemical reactions by writing a
chemical equation in which the chemicals
present before the reaction are on the left of
the arrow, and the chemicals formed by the
reaction are on the right of the arrow
• The arrow indicates the direction of the
change CH4 + O2
CO2 + H2O
Chemical Equations
• In the reaction of methane with oxygen, we have:
CH4 + O2
CO2 + H2O
Reactants
Products
• The chemicals present on the left side of the
equation are known as the reactants
• The chemicals present on the right side of the
equation are known as the products
What is a Chemical Equation?
• An equation that uses the formulas of chemicals
compounds and elements to show the reactants and
products in a chemical change
• Chemicals present before the reaction are on the left of
the arrow (reactants), and the chemicals formed by the
reaction are on the right of the arrow (products)
Ex: CH4 + O2
CO2 + H2O
Balancing Chemical Reactions
• It is important to realize that in a chemical
reaction, atoms are neither created nor
destroyed
• In other words, their must be the same
number of each type of atom on the product
side as on the reactant side of the arrow
••
•
•
•
Balancing Chemical Reactions
In
other
words,
the
reaction
and
table
below
show
Oxygen
Remember,
atoms
beatoms
created
or
destroyed
in
chemical
reactions,
We
can
fix
this
by
putting
in
1atoms,
more
Oxygen
molecule
on1inthe
left
By
the
number
you
can
see
that
the
chemical
Notice,
there
are
2cannot
Oxygen
on
left
side
and
3that
Oxygen
atoms
on
We
group
molecules
by
putting
coefficients
front
ofatom
them:
Thecounting
reaction
below
is together
notof
balanced
is
created
and
2and
Hydrogen
atoms
are
destroyed
they
can only
be
rearranged!
(reactant)
side
1 more
Water
molecule
on
theleft
right
(product)
side
the
right
side;
4byHydrogen
the
side
and 2 apart:
equation
is
balanced
andare
shows
the
actual
numbers
molecules
We can
see
it isalso
notthere
balanced
taking
theonreactants
&ofproducts
Therefore,
the
reaction
cannot
way!
total in
number
of
atoms
musthappen
be
thethis
same
on both
sides
of the
arrow
The
table
now
has
equal
number
of atoms
on
both
sides
of the
equation
Hydrogen
on
the
right
side
involved
this
reaction
CH4
O+2 +2 O2
CO2
H+2+O +2H2O
H
H CH
H
O O
O C O
H OH
O O
Left
Reactant Side
C=
O=
1
2
4
H=
4
9
7
6
9
Total Number of Atoms
Right
H OH
Product Side
O=
1
34
H=
42
C=
Balancing Chemical Reactions
••••• We
In
other
can
fixwords,
this
by
putting
reaction
and
more
table
Water
molecule
show
that
on
the
1front
Oxygen
left(reactant)
atom
By
counting
the
number
of
you
can
see
the
chemical
Remember,
atoms
cannot
be1atoms,
created
orbelow
destroyed
in
chemical
reactions,
group
molecules
byon
putting
coefficients
in
ofon
them:
Notice,
there
is
1the
Oxygen
atoms
left
side
and
2that
Oxygen
atoms
The
reaction
below
istogether
notin
balanced
is
created
and
1only
Hydrogen
molecule
on
the
side and
they
cansee
rearranged!
equation
ismore
balanced
andthe
shows
actual
numbers
atoms
the
right
side;
therefore
chemical
equation
is NOT of
balanced
• side
We
can
it be
is
NOT
balanced
bythe
taking
theright(product)
reactants
& products
•• The
Therefore,
table
thehas
reaction
equal
cannot
number
of
onway!
both
sides
of the
equation
The
total now
number
of
atoms
musthappen
beatoms
the this
same
on both
sides
of the
arrow
molecules
involved
in
this
reaction
apart:
2 H2
H2O + 2 H2O
H OH
H OH
Left
Reactant Side
O=
1
2
42
H=
H H
3
6
6
4
H H
O O
Right
Product Side
O=
2
24
H=
Total Number of Atoms
H+2 + O2
Subscripts and Coefficients
• When balancing chemical equations, it is important to note
that the subscripts can never change
• For example, in the equation below, the subscript of 4 in
methane cannot be changed, neither can the subscripts 2 in
Oxygen, Carbon dioxide and Water
CH4 + 2 O2
CO2 + 2H2O
• Only coefficients can be added by putting whole numbers in
front of the compounds when balancing chemical reactions
How Do we Balance Chemical Equations?
• By placing coefficients in front of each molecule
or compound
• Subscripts cannot be changed!
• Ex: CH4 + 2O2 CO2 + 2H2O
Balancing Chemical Equations
Remember: When balancing chemical equations, it is important to
note that the subscripts can never change!!!!
2
___O
___O
3
2
3
___
2 Mg + ___ O2
___
2 MgO
Practice:
Determine how many atoms of each element are in
each compound below:
1)
2)
3)
4)
2 Na + ___ Cl
___
2
4 Fe + ___
3 O
___
2
___
4 Al + ___
3 O2
2 Na + ___ F
___
2
2
___
NaCl
2 Fe O
___
2 3
___
2 Al2O3
2 NaF
___
Physical States
• In a reaction, we often use symbols to represent the physical state of
the reactants and products
• Look at the reaction below when sodium metal reacts with water:
Na(s) + H2O(l)
H2(g) + NaOH(aq)
• The symbol (s) tells us that Sodium (Na) is in the solid
state
• The symbol (l) tells us the water (H2O) is in the liquid
state
• The symbol (g) tells us the hydrogen (H2) is in the
gaseous state
• Finally, the symbol (aq) tells us that sodium hydroxide
(NaOH) is aqueous or dissolved in water
Symbol
State
(s)
solid
(l)
(g)
(aq)
liquid
gas
aqueous
What do the symbols represent in a
chemical equation?
• The symbols represent the physical state of the
reactants and products
Symbol
State
solid
Na(s) + H2O(l)
H2(g) + NaOH(aq) (s)
(l)
(g)
(aq)
liquid
gas
aqueous
or dissolved
in water
Summary
(you can always write your own summary)
• Explain the Law of Conservation of Mass in your own words
and apply it to chemical reactions:
• What is the difference between the reactants and products
in a chemical reaction?
• Describe the process of balancing chemical reactions, be
sure to explain how you count atoms on both sides of the
equation
• What can you not change when balancing chemical
reactions?
• Is the reaction below balanced? Explain why or why not:
K + Cl2 KCl
Slide 13
UNIT: Chemical Reactions
TOPIC: Properties of Reactions
Objectives: Lesson 1 of 3
•
•
•
•
To learn how we recognize a chemical reaction has took place
To learn what a chemical reactions is
To learn how we balance chemical equations
To learn the symbols for each physical state in a chemical
reaction
Quickwrite
In 1-2 sentences answer one of the questions below:
• What sort of clues do think indicate that a chemical reaction is
happening in your car engine????
• What sort of clues indicate a chemical reaction when you drop a
piece of alka selzter in water????
• What are some by products produced when your body breaks
down sugar, C6H12O6????? What are some clues that this
reaction is occuring in your body????? Hint: think of
temperature!!!!
Evidence for a Chemical Reaction
• How do you know a chemical reaction has occurred?
• Chemists look for visual clues such a color or heat
change, a solid forms, bubbles are produced, a flame
occurs
• However, reactions are not always visible
• Sometimes the only signal that a reaction is occurring is
a change in temperature as heat is produced
What are some clues that a
chemical reaction has occurred?
•
•
•
•
•
A color change
A solid forms
Bubbles form
A heat change
A flame is produced
Chemical Reactions
• Chemists have learned that a chemical change always involves a
rearrangement of the ways in which atoms are grouped and combine
with one another
• For example, consider the reaction that occurs with your laboratory
bunsen burners
• In this reaction, methane (CH4) reacts with oxygen (O2) in the air
• As you know, a flame is produce and heat is released
• As the atoms rearrange themselves, two new chemicals are produced
carbon dioxide (CO2), and water (H2O)
CH4 + O2
CO2 + H2O
Chemical
Reactions
Such a change is called a chemical reaction
•
• Notice, the atoms were rearranged, Oxygen combined with Carbon and
Hydrogen to produce 2 new chemicals: Water & Carbon Dioxide
• Chemical reactions obey the Law of Conservation of Matter which states: Atoms
cannot be destroyed, they can only be rearranged
CH4 + O2
CO2
Methane (CH4)
Water(H
Carbon
Dioxide
2O) (CO2)
Oxygen(O2)
H2O
What is a Chemical Reaction?
• A chemical reaction is the change that occurs when
atoms rearrange themselves and form new
compounds
• Chemical reactions obey the first LAW of
conservation of MASS or MATTER which states:
Atoms and matter cannot be created or destroyed,
they can only be rearranged
Chemical Equations
• We represent chemical reactions by writing a
chemical equation in which the chemicals
present before the reaction are on the left of
the arrow, and the chemicals formed by the
reaction are on the right of the arrow
• The arrow indicates the direction of the
change CH4 + O2
CO2 + H2O
Chemical Equations
• In the reaction of methane with oxygen, we have:
CH4 + O2
CO2 + H2O
Reactants
Products
• The chemicals present on the left side of the
equation are known as the reactants
• The chemicals present on the right side of the
equation are known as the products
What is a Chemical Equation?
• An equation that uses the formulas of chemicals
compounds and elements to show the reactants and
products in a chemical change
• Chemicals present before the reaction are on the left of
the arrow (reactants), and the chemicals formed by the
reaction are on the right of the arrow (products)
Ex: CH4 + O2
CO2 + H2O
Balancing Chemical Reactions
• It is important to realize that in a chemical
reaction, atoms are neither created nor
destroyed
• In other words, their must be the same
number of each type of atom on the product
side as on the reactant side of the arrow
••
•
•
•
Balancing Chemical Reactions
In
other
words,
the
reaction
and
table
below
show
Oxygen
Remember,
atoms
beatoms
created
or
destroyed
in
chemical
reactions,
We
can
fix
this
by
putting
in
1atoms,
more
Oxygen
molecule
on1inthe
left
By
the
number
you
can
see
that
the
chemical
Notice,
there
are
2cannot
Oxygen
on
left
side
and
3that
Oxygen
atoms
on
We
group
molecules
by
putting
coefficients
front
ofatom
them:
Thecounting
reaction
below
is together
notof
balanced
is
created
and
2and
Hydrogen
atoms
are
destroyed
they
can only
be
rearranged!
(reactant)
side
1 more
Water
molecule
on
theleft
right
(product)
side
the
right
side;
4byHydrogen
the
side
and 2 apart:
equation
is
balanced
andare
shows
the
actual
numbers
molecules
We can
see
it isalso
notthere
balanced
taking
theonreactants
&ofproducts
Therefore,
the
reaction
cannot
way!
total in
number
of
atoms
musthappen
be
thethis
same
on both
sides
of the
arrow
The
table
now
has
equal
number
of atoms
on
both
sides
of the
equation
Hydrogen
on
the
right
side
involved
this
reaction
CH4
O+2 +2 O2
CO2
H+2+O +2H2O
H
H CH
H
O O
O C O
H OH
O O
Left
Reactant Side
C=
O=
1
2
4
H=
4
9
7
6
9
Total Number of Atoms
Right
H OH
Product Side
O=
1
34
H=
42
C=
Balancing Chemical Reactions
••••• We
In
other
can
fixwords,
this
by
putting
reaction
and
more
table
Water
molecule
show
that
on
the
1front
Oxygen
left(reactant)
atom
By
counting
the
number
of
you
can
see
the
chemical
Remember,
atoms
cannot
be1atoms,
created
orbelow
destroyed
in
chemical
reactions,
group
molecules
byon
putting
coefficients
in
ofon
them:
Notice,
there
is
1the
Oxygen
atoms
left
side
and
2that
Oxygen
atoms
The
reaction
below
istogether
notin
balanced
is
created
and
1only
Hydrogen
molecule
on
the
side and
they
cansee
rearranged!
equation
ismore
balanced
andthe
shows
actual
numbers
atoms
the
right
side;
therefore
chemical
equation
is NOT of
balanced
• side
We
can
it be
is
NOT
balanced
bythe
taking
theright(product)
reactants
& products
•• The
Therefore,
table
thehas
reaction
equal
cannot
number
of
onway!
both
sides
of the
equation
The
total now
number
of
atoms
musthappen
beatoms
the this
same
on both
sides
of the
arrow
molecules
involved
in
this
reaction
apart:
2 H2
H2O + 2 H2O
H OH
H OH
Left
Reactant Side
O=
1
2
42
H=
H H
3
6
6
4
H H
O O
Right
Product Side
O=
2
24
H=
Total Number of Atoms
H+2 + O2
Subscripts and Coefficients
• When balancing chemical equations, it is important to note
that the subscripts can never change
• For example, in the equation below, the subscript of 4 in
methane cannot be changed, neither can the subscripts 2 in
Oxygen, Carbon dioxide and Water
CH4 + 2 O2
CO2 + 2H2O
• Only coefficients can be added by putting whole numbers in
front of the compounds when balancing chemical reactions
How Do we Balance Chemical Equations?
• By placing coefficients in front of each molecule
or compound
• Subscripts cannot be changed!
• Ex: CH4 + 2O2 CO2 + 2H2O
Balancing Chemical Equations
Remember: When balancing chemical equations, it is important to
note that the subscripts can never change!!!!
2
___O
___O
3
2
3
___
2 Mg + ___ O2
___
2 MgO
Practice:
Determine how many atoms of each element are in
each compound below:
1)
2)
3)
4)
2 Na + ___ Cl
___
2
4 Fe + ___
3 O
___
2
___
4 Al + ___
3 O2
2 Na + ___ F
___
2
2
___
NaCl
2 Fe O
___
2 3
___
2 Al2O3
2 NaF
___
Physical States
• In a reaction, we often use symbols to represent the physical state of
the reactants and products
• Look at the reaction below when sodium metal reacts with water:
Na(s) + H2O(l)
H2(g) + NaOH(aq)
• The symbol (s) tells us that Sodium (Na) is in the solid
state
• The symbol (l) tells us the water (H2O) is in the liquid
state
• The symbol (g) tells us the hydrogen (H2) is in the
gaseous state
• Finally, the symbol (aq) tells us that sodium hydroxide
(NaOH) is aqueous or dissolved in water
Symbol
State
(s)
solid
(l)
(g)
(aq)
liquid
gas
aqueous
What do the symbols represent in a
chemical equation?
• The symbols represent the physical state of the
reactants and products
Symbol
State
solid
Na(s) + H2O(l)
H2(g) + NaOH(aq) (s)
(l)
(g)
(aq)
liquid
gas
aqueous
or dissolved
in water
Summary
(you can always write your own summary)
• Explain the Law of Conservation of Mass in your own words
and apply it to chemical reactions:
• What is the difference between the reactants and products
in a chemical reaction?
• Describe the process of balancing chemical reactions, be
sure to explain how you count atoms on both sides of the
equation
• What can you not change when balancing chemical
reactions?
• Is the reaction below balanced? Explain why or why not:
K + Cl2 KCl
Slide 14
UNIT: Chemical Reactions
TOPIC: Properties of Reactions
Objectives: Lesson 1 of 3
•
•
•
•
To learn how we recognize a chemical reaction has took place
To learn what a chemical reactions is
To learn how we balance chemical equations
To learn the symbols for each physical state in a chemical
reaction
Quickwrite
In 1-2 sentences answer one of the questions below:
• What sort of clues do think indicate that a chemical reaction is
happening in your car engine????
• What sort of clues indicate a chemical reaction when you drop a
piece of alka selzter in water????
• What are some by products produced when your body breaks
down sugar, C6H12O6????? What are some clues that this
reaction is occuring in your body????? Hint: think of
temperature!!!!
Evidence for a Chemical Reaction
• How do you know a chemical reaction has occurred?
• Chemists look for visual clues such a color or heat
change, a solid forms, bubbles are produced, a flame
occurs
• However, reactions are not always visible
• Sometimes the only signal that a reaction is occurring is
a change in temperature as heat is produced
What are some clues that a
chemical reaction has occurred?
•
•
•
•
•
A color change
A solid forms
Bubbles form
A heat change
A flame is produced
Chemical Reactions
• Chemists have learned that a chemical change always involves a
rearrangement of the ways in which atoms are grouped and combine
with one another
• For example, consider the reaction that occurs with your laboratory
bunsen burners
• In this reaction, methane (CH4) reacts with oxygen (O2) in the air
• As you know, a flame is produce and heat is released
• As the atoms rearrange themselves, two new chemicals are produced
carbon dioxide (CO2), and water (H2O)
CH4 + O2
CO2 + H2O
Chemical
Reactions
Such a change is called a chemical reaction
•
• Notice, the atoms were rearranged, Oxygen combined with Carbon and
Hydrogen to produce 2 new chemicals: Water & Carbon Dioxide
• Chemical reactions obey the Law of Conservation of Matter which states: Atoms
cannot be destroyed, they can only be rearranged
CH4 + O2
CO2
Methane (CH4)
Water(H
Carbon
Dioxide
2O) (CO2)
Oxygen(O2)
H2O
What is a Chemical Reaction?
• A chemical reaction is the change that occurs when
atoms rearrange themselves and form new
compounds
• Chemical reactions obey the first LAW of
conservation of MASS or MATTER which states:
Atoms and matter cannot be created or destroyed,
they can only be rearranged
Chemical Equations
• We represent chemical reactions by writing a
chemical equation in which the chemicals
present before the reaction are on the left of
the arrow, and the chemicals formed by the
reaction are on the right of the arrow
• The arrow indicates the direction of the
change CH4 + O2
CO2 + H2O
Chemical Equations
• In the reaction of methane with oxygen, we have:
CH4 + O2
CO2 + H2O
Reactants
Products
• The chemicals present on the left side of the
equation are known as the reactants
• The chemicals present on the right side of the
equation are known as the products
What is a Chemical Equation?
• An equation that uses the formulas of chemicals
compounds and elements to show the reactants and
products in a chemical change
• Chemicals present before the reaction are on the left of
the arrow (reactants), and the chemicals formed by the
reaction are on the right of the arrow (products)
Ex: CH4 + O2
CO2 + H2O
Balancing Chemical Reactions
• It is important to realize that in a chemical
reaction, atoms are neither created nor
destroyed
• In other words, their must be the same
number of each type of atom on the product
side as on the reactant side of the arrow
••
•
•
•
Balancing Chemical Reactions
In
other
words,
the
reaction
and
table
below
show
Oxygen
Remember,
atoms
beatoms
created
or
destroyed
in
chemical
reactions,
We
can
fix
this
by
putting
in
1atoms,
more
Oxygen
molecule
on1inthe
left
By
the
number
you
can
see
that
the
chemical
Notice,
there
are
2cannot
Oxygen
on
left
side
and
3that
Oxygen
atoms
on
We
group
molecules
by
putting
coefficients
front
ofatom
them:
Thecounting
reaction
below
is together
notof
balanced
is
created
and
2and
Hydrogen
atoms
are
destroyed
they
can only
be
rearranged!
(reactant)
side
1 more
Water
molecule
on
theleft
right
(product)
side
the
right
side;
4byHydrogen
the
side
and 2 apart:
equation
is
balanced
andare
shows
the
actual
numbers
molecules
We can
see
it isalso
notthere
balanced
taking
theonreactants
&ofproducts
Therefore,
the
reaction
cannot
way!
total in
number
of
atoms
musthappen
be
thethis
same
on both
sides
of the
arrow
The
table
now
has
equal
number
of atoms
on
both
sides
of the
equation
Hydrogen
on
the
right
side
involved
this
reaction
CH4
O+2 +2 O2
CO2
H+2+O +2H2O
H
H CH
H
O O
O C O
H OH
O O
Left
Reactant Side
C=
O=
1
2
4
H=
4
9
7
6
9
Total Number of Atoms
Right
H OH
Product Side
O=
1
34
H=
42
C=
Balancing Chemical Reactions
••••• We
In
other
can
fixwords,
this
by
putting
reaction
and
more
table
Water
molecule
show
that
on
the
1front
Oxygen
left(reactant)
atom
By
counting
the
number
of
you
can
see
the
chemical
Remember,
atoms
cannot
be1atoms,
created
orbelow
destroyed
in
chemical
reactions,
group
molecules
byon
putting
coefficients
in
ofon
them:
Notice,
there
is
1the
Oxygen
atoms
left
side
and
2that
Oxygen
atoms
The
reaction
below
istogether
notin
balanced
is
created
and
1only
Hydrogen
molecule
on
the
side and
they
cansee
rearranged!
equation
ismore
balanced
andthe
shows
actual
numbers
atoms
the
right
side;
therefore
chemical
equation
is NOT of
balanced
• side
We
can
it be
is
NOT
balanced
bythe
taking
theright(product)
reactants
& products
•• The
Therefore,
table
thehas
reaction
equal
cannot
number
of
onway!
both
sides
of the
equation
The
total now
number
of
atoms
musthappen
beatoms
the this
same
on both
sides
of the
arrow
molecules
involved
in
this
reaction
apart:
2 H2
H2O + 2 H2O
H OH
H OH
Left
Reactant Side
O=
1
2
42
H=
H H
3
6
6
4
H H
O O
Right
Product Side
O=
2
24
H=
Total Number of Atoms
H+2 + O2
Subscripts and Coefficients
• When balancing chemical equations, it is important to note
that the subscripts can never change
• For example, in the equation below, the subscript of 4 in
methane cannot be changed, neither can the subscripts 2 in
Oxygen, Carbon dioxide and Water
CH4 + 2 O2
CO2 + 2H2O
• Only coefficients can be added by putting whole numbers in
front of the compounds when balancing chemical reactions
How Do we Balance Chemical Equations?
• By placing coefficients in front of each molecule
or compound
• Subscripts cannot be changed!
• Ex: CH4 + 2O2 CO2 + 2H2O
Balancing Chemical Equations
Remember: When balancing chemical equations, it is important to
note that the subscripts can never change!!!!
2
___O
___O
3
2
3
___
2 Mg + ___ O2
___
2 MgO
Practice:
Determine how many atoms of each element are in
each compound below:
1)
2)
3)
4)
2 Na + ___ Cl
___
2
4 Fe + ___
3 O
___
2
___
4 Al + ___
3 O2
2 Na + ___ F
___
2
2
___
NaCl
2 Fe O
___
2 3
___
2 Al2O3
2 NaF
___
Physical States
• In a reaction, we often use symbols to represent the physical state of
the reactants and products
• Look at the reaction below when sodium metal reacts with water:
Na(s) + H2O(l)
H2(g) + NaOH(aq)
• The symbol (s) tells us that Sodium (Na) is in the solid
state
• The symbol (l) tells us the water (H2O) is in the liquid
state
• The symbol (g) tells us the hydrogen (H2) is in the
gaseous state
• Finally, the symbol (aq) tells us that sodium hydroxide
(NaOH) is aqueous or dissolved in water
Symbol
State
(s)
solid
(l)
(g)
(aq)
liquid
gas
aqueous
What do the symbols represent in a
chemical equation?
• The symbols represent the physical state of the
reactants and products
Symbol
State
solid
Na(s) + H2O(l)
H2(g) + NaOH(aq) (s)
(l)
(g)
(aq)
liquid
gas
aqueous
or dissolved
in water
Summary
(you can always write your own summary)
• Explain the Law of Conservation of Mass in your own words
and apply it to chemical reactions:
• What is the difference between the reactants and products
in a chemical reaction?
• Describe the process of balancing chemical reactions, be
sure to explain how you count atoms on both sides of the
equation
• What can you not change when balancing chemical
reactions?
• Is the reaction below balanced? Explain why or why not:
K + Cl2 KCl
Slide 15
UNIT: Chemical Reactions
TOPIC: Properties of Reactions
Objectives: Lesson 1 of 3
•
•
•
•
To learn how we recognize a chemical reaction has took place
To learn what a chemical reactions is
To learn how we balance chemical equations
To learn the symbols for each physical state in a chemical
reaction
Quickwrite
In 1-2 sentences answer one of the questions below:
• What sort of clues do think indicate that a chemical reaction is
happening in your car engine????
• What sort of clues indicate a chemical reaction when you drop a
piece of alka selzter in water????
• What are some by products produced when your body breaks
down sugar, C6H12O6????? What are some clues that this
reaction is occuring in your body????? Hint: think of
temperature!!!!
Evidence for a Chemical Reaction
• How do you know a chemical reaction has occurred?
• Chemists look for visual clues such a color or heat
change, a solid forms, bubbles are produced, a flame
occurs
• However, reactions are not always visible
• Sometimes the only signal that a reaction is occurring is
a change in temperature as heat is produced
What are some clues that a
chemical reaction has occurred?
•
•
•
•
•
A color change
A solid forms
Bubbles form
A heat change
A flame is produced
Chemical Reactions
• Chemists have learned that a chemical change always involves a
rearrangement of the ways in which atoms are grouped and combine
with one another
• For example, consider the reaction that occurs with your laboratory
bunsen burners
• In this reaction, methane (CH4) reacts with oxygen (O2) in the air
• As you know, a flame is produce and heat is released
• As the atoms rearrange themselves, two new chemicals are produced
carbon dioxide (CO2), and water (H2O)
CH4 + O2
CO2 + H2O
Chemical
Reactions
Such a change is called a chemical reaction
•
• Notice, the atoms were rearranged, Oxygen combined with Carbon and
Hydrogen to produce 2 new chemicals: Water & Carbon Dioxide
• Chemical reactions obey the Law of Conservation of Matter which states: Atoms
cannot be destroyed, they can only be rearranged
CH4 + O2
CO2
Methane (CH4)
Water(H
Carbon
Dioxide
2O) (CO2)
Oxygen(O2)
H2O
What is a Chemical Reaction?
• A chemical reaction is the change that occurs when
atoms rearrange themselves and form new
compounds
• Chemical reactions obey the first LAW of
conservation of MASS or MATTER which states:
Atoms and matter cannot be created or destroyed,
they can only be rearranged
Chemical Equations
• We represent chemical reactions by writing a
chemical equation in which the chemicals
present before the reaction are on the left of
the arrow, and the chemicals formed by the
reaction are on the right of the arrow
• The arrow indicates the direction of the
change CH4 + O2
CO2 + H2O
Chemical Equations
• In the reaction of methane with oxygen, we have:
CH4 + O2
CO2 + H2O
Reactants
Products
• The chemicals present on the left side of the
equation are known as the reactants
• The chemicals present on the right side of the
equation are known as the products
What is a Chemical Equation?
• An equation that uses the formulas of chemicals
compounds and elements to show the reactants and
products in a chemical change
• Chemicals present before the reaction are on the left of
the arrow (reactants), and the chemicals formed by the
reaction are on the right of the arrow (products)
Ex: CH4 + O2
CO2 + H2O
Balancing Chemical Reactions
• It is important to realize that in a chemical
reaction, atoms are neither created nor
destroyed
• In other words, their must be the same
number of each type of atom on the product
side as on the reactant side of the arrow
••
•
•
•
Balancing Chemical Reactions
In
other
words,
the
reaction
and
table
below
show
Oxygen
Remember,
atoms
beatoms
created
or
destroyed
in
chemical
reactions,
We
can
fix
this
by
putting
in
1atoms,
more
Oxygen
molecule
on1inthe
left
By
the
number
you
can
see
that
the
chemical
Notice,
there
are
2cannot
Oxygen
on
left
side
and
3that
Oxygen
atoms
on
We
group
molecules
by
putting
coefficients
front
ofatom
them:
Thecounting
reaction
below
is together
notof
balanced
is
created
and
2and
Hydrogen
atoms
are
destroyed
they
can only
be
rearranged!
(reactant)
side
1 more
Water
molecule
on
theleft
right
(product)
side
the
right
side;
4byHydrogen
the
side
and 2 apart:
equation
is
balanced
andare
shows
the
actual
numbers
molecules
We can
see
it isalso
notthere
balanced
taking
theonreactants
&ofproducts
Therefore,
the
reaction
cannot
way!
total in
number
of
atoms
musthappen
be
thethis
same
on both
sides
of the
arrow
The
table
now
has
equal
number
of atoms
on
both
sides
of the
equation
Hydrogen
on
the
right
side
involved
this
reaction
CH4
O+2 +2 O2
CO2
H+2+O +2H2O
H
H CH
H
O O
O C O
H OH
O O
Left
Reactant Side
C=
O=
1
2
4
H=
4
9
7
6
9
Total Number of Atoms
Right
H OH
Product Side
O=
1
34
H=
42
C=
Balancing Chemical Reactions
••••• We
In
other
can
fixwords,
this
by
putting
reaction
and
more
table
Water
molecule
show
that
on
the
1front
Oxygen
left(reactant)
atom
By
counting
the
number
of
you
can
see
the
chemical
Remember,
atoms
cannot
be1atoms,
created
orbelow
destroyed
in
chemical
reactions,
group
molecules
byon
putting
coefficients
in
ofon
them:
Notice,
there
is
1the
Oxygen
atoms
left
side
and
2that
Oxygen
atoms
The
reaction
below
istogether
notin
balanced
is
created
and
1only
Hydrogen
molecule
on
the
side and
they
cansee
rearranged!
equation
ismore
balanced
andthe
shows
actual
numbers
atoms
the
right
side;
therefore
chemical
equation
is NOT of
balanced
• side
We
can
it be
is
NOT
balanced
bythe
taking
theright(product)
reactants
& products
•• The
Therefore,
table
thehas
reaction
equal
cannot
number
of
onway!
both
sides
of the
equation
The
total now
number
of
atoms
musthappen
beatoms
the this
same
on both
sides
of the
arrow
molecules
involved
in
this
reaction
apart:
2 H2
H2O + 2 H2O
H OH
H OH
Left
Reactant Side
O=
1
2
42
H=
H H
3
6
6
4
H H
O O
Right
Product Side
O=
2
24
H=
Total Number of Atoms
H+2 + O2
Subscripts and Coefficients
• When balancing chemical equations, it is important to note
that the subscripts can never change
• For example, in the equation below, the subscript of 4 in
methane cannot be changed, neither can the subscripts 2 in
Oxygen, Carbon dioxide and Water
CH4 + 2 O2
CO2 + 2H2O
• Only coefficients can be added by putting whole numbers in
front of the compounds when balancing chemical reactions
How Do we Balance Chemical Equations?
• By placing coefficients in front of each molecule
or compound
• Subscripts cannot be changed!
• Ex: CH4 + 2O2 CO2 + 2H2O
Balancing Chemical Equations
Remember: When balancing chemical equations, it is important to
note that the subscripts can never change!!!!
2
___O
___O
3
2
3
___
2 Mg + ___ O2
___
2 MgO
Practice:
Determine how many atoms of each element are in
each compound below:
1)
2)
3)
4)
2 Na + ___ Cl
___
2
4 Fe + ___
3 O
___
2
___
4 Al + ___
3 O2
2 Na + ___ F
___
2
2
___
NaCl
2 Fe O
___
2 3
___
2 Al2O3
2 NaF
___
Physical States
• In a reaction, we often use symbols to represent the physical state of
the reactants and products
• Look at the reaction below when sodium metal reacts with water:
Na(s) + H2O(l)
H2(g) + NaOH(aq)
• The symbol (s) tells us that Sodium (Na) is in the solid
state
• The symbol (l) tells us the water (H2O) is in the liquid
state
• The symbol (g) tells us the hydrogen (H2) is in the
gaseous state
• Finally, the symbol (aq) tells us that sodium hydroxide
(NaOH) is aqueous or dissolved in water
Symbol
State
(s)
solid
(l)
(g)
(aq)
liquid
gas
aqueous
What do the symbols represent in a
chemical equation?
• The symbols represent the physical state of the
reactants and products
Symbol
State
solid
Na(s) + H2O(l)
H2(g) + NaOH(aq) (s)
(l)
(g)
(aq)
liquid
gas
aqueous
or dissolved
in water
Summary
(you can always write your own summary)
• Explain the Law of Conservation of Mass in your own words
and apply it to chemical reactions:
• What is the difference between the reactants and products
in a chemical reaction?
• Describe the process of balancing chemical reactions, be
sure to explain how you count atoms on both sides of the
equation
• What can you not change when balancing chemical
reactions?
• Is the reaction below balanced? Explain why or why not:
K + Cl2 KCl
Slide 16
UNIT: Chemical Reactions
TOPIC: Properties of Reactions
Objectives: Lesson 1 of 3
•
•
•
•
To learn how we recognize a chemical reaction has took place
To learn what a chemical reactions is
To learn how we balance chemical equations
To learn the symbols for each physical state in a chemical
reaction
Quickwrite
In 1-2 sentences answer one of the questions below:
• What sort of clues do think indicate that a chemical reaction is
happening in your car engine????
• What sort of clues indicate a chemical reaction when you drop a
piece of alka selzter in water????
• What are some by products produced when your body breaks
down sugar, C6H12O6????? What are some clues that this
reaction is occuring in your body????? Hint: think of
temperature!!!!
Evidence for a Chemical Reaction
• How do you know a chemical reaction has occurred?
• Chemists look for visual clues such a color or heat
change, a solid forms, bubbles are produced, a flame
occurs
• However, reactions are not always visible
• Sometimes the only signal that a reaction is occurring is
a change in temperature as heat is produced
What are some clues that a
chemical reaction has occurred?
•
•
•
•
•
A color change
A solid forms
Bubbles form
A heat change
A flame is produced
Chemical Reactions
• Chemists have learned that a chemical change always involves a
rearrangement of the ways in which atoms are grouped and combine
with one another
• For example, consider the reaction that occurs with your laboratory
bunsen burners
• In this reaction, methane (CH4) reacts with oxygen (O2) in the air
• As you know, a flame is produce and heat is released
• As the atoms rearrange themselves, two new chemicals are produced
carbon dioxide (CO2), and water (H2O)
CH4 + O2
CO2 + H2O
Chemical
Reactions
Such a change is called a chemical reaction
•
• Notice, the atoms were rearranged, Oxygen combined with Carbon and
Hydrogen to produce 2 new chemicals: Water & Carbon Dioxide
• Chemical reactions obey the Law of Conservation of Matter which states: Atoms
cannot be destroyed, they can only be rearranged
CH4 + O2
CO2
Methane (CH4)
Water(H
Carbon
Dioxide
2O) (CO2)
Oxygen(O2)
H2O
What is a Chemical Reaction?
• A chemical reaction is the change that occurs when
atoms rearrange themselves and form new
compounds
• Chemical reactions obey the first LAW of
conservation of MASS or MATTER which states:
Atoms and matter cannot be created or destroyed,
they can only be rearranged
Chemical Equations
• We represent chemical reactions by writing a
chemical equation in which the chemicals
present before the reaction are on the left of
the arrow, and the chemicals formed by the
reaction are on the right of the arrow
• The arrow indicates the direction of the
change CH4 + O2
CO2 + H2O
Chemical Equations
• In the reaction of methane with oxygen, we have:
CH4 + O2
CO2 + H2O
Reactants
Products
• The chemicals present on the left side of the
equation are known as the reactants
• The chemicals present on the right side of the
equation are known as the products
What is a Chemical Equation?
• An equation that uses the formulas of chemicals
compounds and elements to show the reactants and
products in a chemical change
• Chemicals present before the reaction are on the left of
the arrow (reactants), and the chemicals formed by the
reaction are on the right of the arrow (products)
Ex: CH4 + O2
CO2 + H2O
Balancing Chemical Reactions
• It is important to realize that in a chemical
reaction, atoms are neither created nor
destroyed
• In other words, their must be the same
number of each type of atom on the product
side as on the reactant side of the arrow
••
•
•
•
Balancing Chemical Reactions
In
other
words,
the
reaction
and
table
below
show
Oxygen
Remember,
atoms
beatoms
created
or
destroyed
in
chemical
reactions,
We
can
fix
this
by
putting
in
1atoms,
more
Oxygen
molecule
on1inthe
left
By
the
number
you
can
see
that
the
chemical
Notice,
there
are
2cannot
Oxygen
on
left
side
and
3that
Oxygen
atoms
on
We
group
molecules
by
putting
coefficients
front
ofatom
them:
Thecounting
reaction
below
is together
notof
balanced
is
created
and
2and
Hydrogen
atoms
are
destroyed
they
can only
be
rearranged!
(reactant)
side
1 more
Water
molecule
on
theleft
right
(product)
side
the
right
side;
4byHydrogen
the
side
and 2 apart:
equation
is
balanced
andare
shows
the
actual
numbers
molecules
We can
see
it isalso
notthere
balanced
taking
theonreactants
&ofproducts
Therefore,
the
reaction
cannot
way!
total in
number
of
atoms
musthappen
be
thethis
same
on both
sides
of the
arrow
The
table
now
has
equal
number
of atoms
on
both
sides
of the
equation
Hydrogen
on
the
right
side
involved
this
reaction
CH4
O+2 +2 O2
CO2
H+2+O +2H2O
H
H CH
H
O O
O C O
H OH
O O
Left
Reactant Side
C=
O=
1
2
4
H=
4
9
7
6
9
Total Number of Atoms
Right
H OH
Product Side
O=
1
34
H=
42
C=
Balancing Chemical Reactions
••••• We
In
other
can
fixwords,
this
by
putting
reaction
and
more
table
Water
molecule
show
that
on
the
1front
Oxygen
left(reactant)
atom
By
counting
the
number
of
you
can
see
the
chemical
Remember,
atoms
cannot
be1atoms,
created
orbelow
destroyed
in
chemical
reactions,
group
molecules
byon
putting
coefficients
in
ofon
them:
Notice,
there
is
1the
Oxygen
atoms
left
side
and
2that
Oxygen
atoms
The
reaction
below
istogether
notin
balanced
is
created
and
1only
Hydrogen
molecule
on
the
side and
they
cansee
rearranged!
equation
ismore
balanced
andthe
shows
actual
numbers
atoms
the
right
side;
therefore
chemical
equation
is NOT of
balanced
• side
We
can
it be
is
NOT
balanced
bythe
taking
theright(product)
reactants
& products
•• The
Therefore,
table
thehas
reaction
equal
cannot
number
of
onway!
both
sides
of the
equation
The
total now
number
of
atoms
musthappen
beatoms
the this
same
on both
sides
of the
arrow
molecules
involved
in
this
reaction
apart:
2 H2
H2O + 2 H2O
H OH
H OH
Left
Reactant Side
O=
1
2
42
H=
H H
3
6
6
4
H H
O O
Right
Product Side
O=
2
24
H=
Total Number of Atoms
H+2 + O2
Subscripts and Coefficients
• When balancing chemical equations, it is important to note
that the subscripts can never change
• For example, in the equation below, the subscript of 4 in
methane cannot be changed, neither can the subscripts 2 in
Oxygen, Carbon dioxide and Water
CH4 + 2 O2
CO2 + 2H2O
• Only coefficients can be added by putting whole numbers in
front of the compounds when balancing chemical reactions
How Do we Balance Chemical Equations?
• By placing coefficients in front of each molecule
or compound
• Subscripts cannot be changed!
• Ex: CH4 + 2O2 CO2 + 2H2O
Balancing Chemical Equations
Remember: When balancing chemical equations, it is important to
note that the subscripts can never change!!!!
2
___O
___O
3
2
3
___
2 Mg + ___ O2
___
2 MgO
Practice:
Determine how many atoms of each element are in
each compound below:
1)
2)
3)
4)
2 Na + ___ Cl
___
2
4 Fe + ___
3 O
___
2
___
4 Al + ___
3 O2
2 Na + ___ F
___
2
2
___
NaCl
2 Fe O
___
2 3
___
2 Al2O3
2 NaF
___
Physical States
• In a reaction, we often use symbols to represent the physical state of
the reactants and products
• Look at the reaction below when sodium metal reacts with water:
Na(s) + H2O(l)
H2(g) + NaOH(aq)
• The symbol (s) tells us that Sodium (Na) is in the solid
state
• The symbol (l) tells us the water (H2O) is in the liquid
state
• The symbol (g) tells us the hydrogen (H2) is in the
gaseous state
• Finally, the symbol (aq) tells us that sodium hydroxide
(NaOH) is aqueous or dissolved in water
Symbol
State
(s)
solid
(l)
(g)
(aq)
liquid
gas
aqueous
What do the symbols represent in a
chemical equation?
• The symbols represent the physical state of the
reactants and products
Symbol
State
solid
Na(s) + H2O(l)
H2(g) + NaOH(aq) (s)
(l)
(g)
(aq)
liquid
gas
aqueous
or dissolved
in water
Summary
(you can always write your own summary)
• Explain the Law of Conservation of Mass in your own words
and apply it to chemical reactions:
• What is the difference between the reactants and products
in a chemical reaction?
• Describe the process of balancing chemical reactions, be
sure to explain how you count atoms on both sides of the
equation
• What can you not change when balancing chemical
reactions?
• Is the reaction below balanced? Explain why or why not:
K + Cl2 KCl
Slide 17
UNIT: Chemical Reactions
TOPIC: Properties of Reactions
Objectives: Lesson 1 of 3
•
•
•
•
To learn how we recognize a chemical reaction has took place
To learn what a chemical reactions is
To learn how we balance chemical equations
To learn the symbols for each physical state in a chemical
reaction
Quickwrite
In 1-2 sentences answer one of the questions below:
• What sort of clues do think indicate that a chemical reaction is
happening in your car engine????
• What sort of clues indicate a chemical reaction when you drop a
piece of alka selzter in water????
• What are some by products produced when your body breaks
down sugar, C6H12O6????? What are some clues that this
reaction is occuring in your body????? Hint: think of
temperature!!!!
Evidence for a Chemical Reaction
• How do you know a chemical reaction has occurred?
• Chemists look for visual clues such a color or heat
change, a solid forms, bubbles are produced, a flame
occurs
• However, reactions are not always visible
• Sometimes the only signal that a reaction is occurring is
a change in temperature as heat is produced
What are some clues that a
chemical reaction has occurred?
•
•
•
•
•
A color change
A solid forms
Bubbles form
A heat change
A flame is produced
Chemical Reactions
• Chemists have learned that a chemical change always involves a
rearrangement of the ways in which atoms are grouped and combine
with one another
• For example, consider the reaction that occurs with your laboratory
bunsen burners
• In this reaction, methane (CH4) reacts with oxygen (O2) in the air
• As you know, a flame is produce and heat is released
• As the atoms rearrange themselves, two new chemicals are produced
carbon dioxide (CO2), and water (H2O)
CH4 + O2
CO2 + H2O
Chemical
Reactions
Such a change is called a chemical reaction
•
• Notice, the atoms were rearranged, Oxygen combined with Carbon and
Hydrogen to produce 2 new chemicals: Water & Carbon Dioxide
• Chemical reactions obey the Law of Conservation of Matter which states: Atoms
cannot be destroyed, they can only be rearranged
CH4 + O2
CO2
Methane (CH4)
Water(H
Carbon
Dioxide
2O) (CO2)
Oxygen(O2)
H2O
What is a Chemical Reaction?
• A chemical reaction is the change that occurs when
atoms rearrange themselves and form new
compounds
• Chemical reactions obey the first LAW of
conservation of MASS or MATTER which states:
Atoms and matter cannot be created or destroyed,
they can only be rearranged
Chemical Equations
• We represent chemical reactions by writing a
chemical equation in which the chemicals
present before the reaction are on the left of
the arrow, and the chemicals formed by the
reaction are on the right of the arrow
• The arrow indicates the direction of the
change CH4 + O2
CO2 + H2O
Chemical Equations
• In the reaction of methane with oxygen, we have:
CH4 + O2
CO2 + H2O
Reactants
Products
• The chemicals present on the left side of the
equation are known as the reactants
• The chemicals present on the right side of the
equation are known as the products
What is a Chemical Equation?
• An equation that uses the formulas of chemicals
compounds and elements to show the reactants and
products in a chemical change
• Chemicals present before the reaction are on the left of
the arrow (reactants), and the chemicals formed by the
reaction are on the right of the arrow (products)
Ex: CH4 + O2
CO2 + H2O
Balancing Chemical Reactions
• It is important to realize that in a chemical
reaction, atoms are neither created nor
destroyed
• In other words, their must be the same
number of each type of atom on the product
side as on the reactant side of the arrow
••
•
•
•
Balancing Chemical Reactions
In
other
words,
the
reaction
and
table
below
show
Oxygen
Remember,
atoms
beatoms
created
or
destroyed
in
chemical
reactions,
We
can
fix
this
by
putting
in
1atoms,
more
Oxygen
molecule
on1inthe
left
By
the
number
you
can
see
that
the
chemical
Notice,
there
are
2cannot
Oxygen
on
left
side
and
3that
Oxygen
atoms
on
We
group
molecules
by
putting
coefficients
front
ofatom
them:
Thecounting
reaction
below
is together
notof
balanced
is
created
and
2and
Hydrogen
atoms
are
destroyed
they
can only
be
rearranged!
(reactant)
side
1 more
Water
molecule
on
theleft
right
(product)
side
the
right
side;
4byHydrogen
the
side
and 2 apart:
equation
is
balanced
andare
shows
the
actual
numbers
molecules
We can
see
it isalso
notthere
balanced
taking
theonreactants
&ofproducts
Therefore,
the
reaction
cannot
way!
total in
number
of
atoms
musthappen
be
thethis
same
on both
sides
of the
arrow
The
table
now
has
equal
number
of atoms
on
both
sides
of the
equation
Hydrogen
on
the
right
side
involved
this
reaction
CH4
O+2 +2 O2
CO2
H+2+O +2H2O
H
H CH
H
O O
O C O
H OH
O O
Left
Reactant Side
C=
O=
1
2
4
H=
4
9
7
6
9
Total Number of Atoms
Right
H OH
Product Side
O=
1
34
H=
42
C=
Balancing Chemical Reactions
••••• We
In
other
can
fixwords,
this
by
putting
reaction
and
more
table
Water
molecule
show
that
on
the
1front
Oxygen
left(reactant)
atom
By
counting
the
number
of
you
can
see
the
chemical
Remember,
atoms
cannot
be1atoms,
created
orbelow
destroyed
in
chemical
reactions,
group
molecules
byon
putting
coefficients
in
ofon
them:
Notice,
there
is
1the
Oxygen
atoms
left
side
and
2that
Oxygen
atoms
The
reaction
below
istogether
notin
balanced
is
created
and
1only
Hydrogen
molecule
on
the
side and
they
cansee
rearranged!
equation
ismore
balanced
andthe
shows
actual
numbers
atoms
the
right
side;
therefore
chemical
equation
is NOT of
balanced
• side
We
can
it be
is
NOT
balanced
bythe
taking
theright(product)
reactants
& products
•• The
Therefore,
table
thehas
reaction
equal
cannot
number
of
onway!
both
sides
of the
equation
The
total now
number
of
atoms
musthappen
beatoms
the this
same
on both
sides
of the
arrow
molecules
involved
in
this
reaction
apart:
2 H2
H2O + 2 H2O
H OH
H OH
Left
Reactant Side
O=
1
2
42
H=
H H
3
6
6
4
H H
O O
Right
Product Side
O=
2
24
H=
Total Number of Atoms
H+2 + O2
Subscripts and Coefficients
• When balancing chemical equations, it is important to note
that the subscripts can never change
• For example, in the equation below, the subscript of 4 in
methane cannot be changed, neither can the subscripts 2 in
Oxygen, Carbon dioxide and Water
CH4 + 2 O2
CO2 + 2H2O
• Only coefficients can be added by putting whole numbers in
front of the compounds when balancing chemical reactions
How Do we Balance Chemical Equations?
• By placing coefficients in front of each molecule
or compound
• Subscripts cannot be changed!
• Ex: CH4 + 2O2 CO2 + 2H2O
Balancing Chemical Equations
Remember: When balancing chemical equations, it is important to
note that the subscripts can never change!!!!
2
___O
___O
3
2
3
___
2 Mg + ___ O2
___
2 MgO
Practice:
Determine how many atoms of each element are in
each compound below:
1)
2)
3)
4)
2 Na + ___ Cl
___
2
4 Fe + ___
3 O
___
2
___
4 Al + ___
3 O2
2 Na + ___ F
___
2
2
___
NaCl
2 Fe O
___
2 3
___
2 Al2O3
2 NaF
___
Physical States
• In a reaction, we often use symbols to represent the physical state of
the reactants and products
• Look at the reaction below when sodium metal reacts with water:
Na(s) + H2O(l)
H2(g) + NaOH(aq)
• The symbol (s) tells us that Sodium (Na) is in the solid
state
• The symbol (l) tells us the water (H2O) is in the liquid
state
• The symbol (g) tells us the hydrogen (H2) is in the
gaseous state
• Finally, the symbol (aq) tells us that sodium hydroxide
(NaOH) is aqueous or dissolved in water
Symbol
State
(s)
solid
(l)
(g)
(aq)
liquid
gas
aqueous
What do the symbols represent in a
chemical equation?
• The symbols represent the physical state of the
reactants and products
Symbol
State
solid
Na(s) + H2O(l)
H2(g) + NaOH(aq) (s)
(l)
(g)
(aq)
liquid
gas
aqueous
or dissolved
in water
Summary
(you can always write your own summary)
• Explain the Law of Conservation of Mass in your own words
and apply it to chemical reactions:
• What is the difference between the reactants and products
in a chemical reaction?
• Describe the process of balancing chemical reactions, be
sure to explain how you count atoms on both sides of the
equation
• What can you not change when balancing chemical
reactions?
• Is the reaction below balanced? Explain why or why not:
K + Cl2 KCl
Slide 18
UNIT: Chemical Reactions
TOPIC: Properties of Reactions
Objectives: Lesson 1 of 3
•
•
•
•
To learn how we recognize a chemical reaction has took place
To learn what a chemical reactions is
To learn how we balance chemical equations
To learn the symbols for each physical state in a chemical
reaction
Quickwrite
In 1-2 sentences answer one of the questions below:
• What sort of clues do think indicate that a chemical reaction is
happening in your car engine????
• What sort of clues indicate a chemical reaction when you drop a
piece of alka selzter in water????
• What are some by products produced when your body breaks
down sugar, C6H12O6????? What are some clues that this
reaction is occuring in your body????? Hint: think of
temperature!!!!
Evidence for a Chemical Reaction
• How do you know a chemical reaction has occurred?
• Chemists look for visual clues such a color or heat
change, a solid forms, bubbles are produced, a flame
occurs
• However, reactions are not always visible
• Sometimes the only signal that a reaction is occurring is
a change in temperature as heat is produced
What are some clues that a
chemical reaction has occurred?
•
•
•
•
•
A color change
A solid forms
Bubbles form
A heat change
A flame is produced
Chemical Reactions
• Chemists have learned that a chemical change always involves a
rearrangement of the ways in which atoms are grouped and combine
with one another
• For example, consider the reaction that occurs with your laboratory
bunsen burners
• In this reaction, methane (CH4) reacts with oxygen (O2) in the air
• As you know, a flame is produce and heat is released
• As the atoms rearrange themselves, two new chemicals are produced
carbon dioxide (CO2), and water (H2O)
CH4 + O2
CO2 + H2O
Chemical
Reactions
Such a change is called a chemical reaction
•
• Notice, the atoms were rearranged, Oxygen combined with Carbon and
Hydrogen to produce 2 new chemicals: Water & Carbon Dioxide
• Chemical reactions obey the Law of Conservation of Matter which states: Atoms
cannot be destroyed, they can only be rearranged
CH4 + O2
CO2
Methane (CH4)
Water(H
Carbon
Dioxide
2O) (CO2)
Oxygen(O2)
H2O
What is a Chemical Reaction?
• A chemical reaction is the change that occurs when
atoms rearrange themselves and form new
compounds
• Chemical reactions obey the first LAW of
conservation of MASS or MATTER which states:
Atoms and matter cannot be created or destroyed,
they can only be rearranged
Chemical Equations
• We represent chemical reactions by writing a
chemical equation in which the chemicals
present before the reaction are on the left of
the arrow, and the chemicals formed by the
reaction are on the right of the arrow
• The arrow indicates the direction of the
change CH4 + O2
CO2 + H2O
Chemical Equations
• In the reaction of methane with oxygen, we have:
CH4 + O2
CO2 + H2O
Reactants
Products
• The chemicals present on the left side of the
equation are known as the reactants
• The chemicals present on the right side of the
equation are known as the products
What is a Chemical Equation?
• An equation that uses the formulas of chemicals
compounds and elements to show the reactants and
products in a chemical change
• Chemicals present before the reaction are on the left of
the arrow (reactants), and the chemicals formed by the
reaction are on the right of the arrow (products)
Ex: CH4 + O2
CO2 + H2O
Balancing Chemical Reactions
• It is important to realize that in a chemical
reaction, atoms are neither created nor
destroyed
• In other words, their must be the same
number of each type of atom on the product
side as on the reactant side of the arrow
••
•
•
•
Balancing Chemical Reactions
In
other
words,
the
reaction
and
table
below
show
Oxygen
Remember,
atoms
beatoms
created
or
destroyed
in
chemical
reactions,
We
can
fix
this
by
putting
in
1atoms,
more
Oxygen
molecule
on1inthe
left
By
the
number
you
can
see
that
the
chemical
Notice,
there
are
2cannot
Oxygen
on
left
side
and
3that
Oxygen
atoms
on
We
group
molecules
by
putting
coefficients
front
ofatom
them:
Thecounting
reaction
below
is together
notof
balanced
is
created
and
2and
Hydrogen
atoms
are
destroyed
they
can only
be
rearranged!
(reactant)
side
1 more
Water
molecule
on
theleft
right
(product)
side
the
right
side;
4byHydrogen
the
side
and 2 apart:
equation
is
balanced
andare
shows
the
actual
numbers
molecules
We can
see
it isalso
notthere
balanced
taking
theonreactants
&ofproducts
Therefore,
the
reaction
cannot
way!
total in
number
of
atoms
musthappen
be
thethis
same
on both
sides
of the
arrow
The
table
now
has
equal
number
of atoms
on
both
sides
of the
equation
Hydrogen
on
the
right
side
involved
this
reaction
CH4
O+2 +2 O2
CO2
H+2+O +2H2O
H
H CH
H
O O
O C O
H OH
O O
Left
Reactant Side
C=
O=
1
2
4
H=
4
9
7
6
9
Total Number of Atoms
Right
H OH
Product Side
O=
1
34
H=
42
C=
Balancing Chemical Reactions
••••• We
In
other
can
fixwords,
this
by
putting
reaction
and
more
table
Water
molecule
show
that
on
the
1front
Oxygen
left(reactant)
atom
By
counting
the
number
of
you
can
see
the
chemical
Remember,
atoms
cannot
be1atoms,
created
orbelow
destroyed
in
chemical
reactions,
group
molecules
byon
putting
coefficients
in
ofon
them:
Notice,
there
is
1the
Oxygen
atoms
left
side
and
2that
Oxygen
atoms
The
reaction
below
istogether
notin
balanced
is
created
and
1only
Hydrogen
molecule
on
the
side and
they
cansee
rearranged!
equation
ismore
balanced
andthe
shows
actual
numbers
atoms
the
right
side;
therefore
chemical
equation
is NOT of
balanced
• side
We
can
it be
is
NOT
balanced
bythe
taking
theright(product)
reactants
& products
•• The
Therefore,
table
thehas
reaction
equal
cannot
number
of
onway!
both
sides
of the
equation
The
total now
number
of
atoms
musthappen
beatoms
the this
same
on both
sides
of the
arrow
molecules
involved
in
this
reaction
apart:
2 H2
H2O + 2 H2O
H OH
H OH
Left
Reactant Side
O=
1
2
42
H=
H H
3
6
6
4
H H
O O
Right
Product Side
O=
2
24
H=
Total Number of Atoms
H+2 + O2
Subscripts and Coefficients
• When balancing chemical equations, it is important to note
that the subscripts can never change
• For example, in the equation below, the subscript of 4 in
methane cannot be changed, neither can the subscripts 2 in
Oxygen, Carbon dioxide and Water
CH4 + 2 O2
CO2 + 2H2O
• Only coefficients can be added by putting whole numbers in
front of the compounds when balancing chemical reactions
How Do we Balance Chemical Equations?
• By placing coefficients in front of each molecule
or compound
• Subscripts cannot be changed!
• Ex: CH4 + 2O2 CO2 + 2H2O
Balancing Chemical Equations
Remember: When balancing chemical equations, it is important to
note that the subscripts can never change!!!!
2
___O
___O
3
2
3
___
2 Mg + ___ O2
___
2 MgO
Practice:
Determine how many atoms of each element are in
each compound below:
1)
2)
3)
4)
2 Na + ___ Cl
___
2
4 Fe + ___
3 O
___
2
___
4 Al + ___
3 O2
2 Na + ___ F
___
2
2
___
NaCl
2 Fe O
___
2 3
___
2 Al2O3
2 NaF
___
Physical States
• In a reaction, we often use symbols to represent the physical state of
the reactants and products
• Look at the reaction below when sodium metal reacts with water:
Na(s) + H2O(l)
H2(g) + NaOH(aq)
• The symbol (s) tells us that Sodium (Na) is in the solid
state
• The symbol (l) tells us the water (H2O) is in the liquid
state
• The symbol (g) tells us the hydrogen (H2) is in the
gaseous state
• Finally, the symbol (aq) tells us that sodium hydroxide
(NaOH) is aqueous or dissolved in water
Symbol
State
(s)
solid
(l)
(g)
(aq)
liquid
gas
aqueous
What do the symbols represent in a
chemical equation?
• The symbols represent the physical state of the
reactants and products
Symbol
State
solid
Na(s) + H2O(l)
H2(g) + NaOH(aq) (s)
(l)
(g)
(aq)
liquid
gas
aqueous
or dissolved
in water
Summary
(you can always write your own summary)
• Explain the Law of Conservation of Mass in your own words
and apply it to chemical reactions:
• What is the difference between the reactants and products
in a chemical reaction?
• Describe the process of balancing chemical reactions, be
sure to explain how you count atoms on both sides of the
equation
• What can you not change when balancing chemical
reactions?
• Is the reaction below balanced? Explain why or why not:
K + Cl2 KCl
Slide 19
UNIT: Chemical Reactions
TOPIC: Properties of Reactions
Objectives: Lesson 1 of 3
•
•
•
•
To learn how we recognize a chemical reaction has took place
To learn what a chemical reactions is
To learn how we balance chemical equations
To learn the symbols for each physical state in a chemical
reaction
Quickwrite
In 1-2 sentences answer one of the questions below:
• What sort of clues do think indicate that a chemical reaction is
happening in your car engine????
• What sort of clues indicate a chemical reaction when you drop a
piece of alka selzter in water????
• What are some by products produced when your body breaks
down sugar, C6H12O6????? What are some clues that this
reaction is occuring in your body????? Hint: think of
temperature!!!!
Evidence for a Chemical Reaction
• How do you know a chemical reaction has occurred?
• Chemists look for visual clues such a color or heat
change, a solid forms, bubbles are produced, a flame
occurs
• However, reactions are not always visible
• Sometimes the only signal that a reaction is occurring is
a change in temperature as heat is produced
What are some clues that a
chemical reaction has occurred?
•
•
•
•
•
A color change
A solid forms
Bubbles form
A heat change
A flame is produced
Chemical Reactions
• Chemists have learned that a chemical change always involves a
rearrangement of the ways in which atoms are grouped and combine
with one another
• For example, consider the reaction that occurs with your laboratory
bunsen burners
• In this reaction, methane (CH4) reacts with oxygen (O2) in the air
• As you know, a flame is produce and heat is released
• As the atoms rearrange themselves, two new chemicals are produced
carbon dioxide (CO2), and water (H2O)
CH4 + O2
CO2 + H2O
Chemical
Reactions
Such a change is called a chemical reaction
•
• Notice, the atoms were rearranged, Oxygen combined with Carbon and
Hydrogen to produce 2 new chemicals: Water & Carbon Dioxide
• Chemical reactions obey the Law of Conservation of Matter which states: Atoms
cannot be destroyed, they can only be rearranged
CH4 + O2
CO2
Methane (CH4)
Water(H
Carbon
Dioxide
2O) (CO2)
Oxygen(O2)
H2O
What is a Chemical Reaction?
• A chemical reaction is the change that occurs when
atoms rearrange themselves and form new
compounds
• Chemical reactions obey the first LAW of
conservation of MASS or MATTER which states:
Atoms and matter cannot be created or destroyed,
they can only be rearranged
Chemical Equations
• We represent chemical reactions by writing a
chemical equation in which the chemicals
present before the reaction are on the left of
the arrow, and the chemicals formed by the
reaction are on the right of the arrow
• The arrow indicates the direction of the
change CH4 + O2
CO2 + H2O
Chemical Equations
• In the reaction of methane with oxygen, we have:
CH4 + O2
CO2 + H2O
Reactants
Products
• The chemicals present on the left side of the
equation are known as the reactants
• The chemicals present on the right side of the
equation are known as the products
What is a Chemical Equation?
• An equation that uses the formulas of chemicals
compounds and elements to show the reactants and
products in a chemical change
• Chemicals present before the reaction are on the left of
the arrow (reactants), and the chemicals formed by the
reaction are on the right of the arrow (products)
Ex: CH4 + O2
CO2 + H2O
Balancing Chemical Reactions
• It is important to realize that in a chemical
reaction, atoms are neither created nor
destroyed
• In other words, their must be the same
number of each type of atom on the product
side as on the reactant side of the arrow
••
•
•
•
Balancing Chemical Reactions
In
other
words,
the
reaction
and
table
below
show
Oxygen
Remember,
atoms
beatoms
created
or
destroyed
in
chemical
reactions,
We
can
fix
this
by
putting
in
1atoms,
more
Oxygen
molecule
on1inthe
left
By
the
number
you
can
see
that
the
chemical
Notice,
there
are
2cannot
Oxygen
on
left
side
and
3that
Oxygen
atoms
on
We
group
molecules
by
putting
coefficients
front
ofatom
them:
Thecounting
reaction
below
is together
notof
balanced
is
created
and
2and
Hydrogen
atoms
are
destroyed
they
can only
be
rearranged!
(reactant)
side
1 more
Water
molecule
on
theleft
right
(product)
side
the
right
side;
4byHydrogen
the
side
and 2 apart:
equation
is
balanced
andare
shows
the
actual
numbers
molecules
We can
see
it isalso
notthere
balanced
taking
theonreactants
&ofproducts
Therefore,
the
reaction
cannot
way!
total in
number
of
atoms
musthappen
be
thethis
same
on both
sides
of the
arrow
The
table
now
has
equal
number
of atoms
on
both
sides
of the
equation
Hydrogen
on
the
right
side
involved
this
reaction
CH4
O+2 +2 O2
CO2
H+2+O +2H2O
H
H CH
H
O O
O C O
H OH
O O
Left
Reactant Side
C=
O=
1
2
4
H=
4
9
7
6
9
Total Number of Atoms
Right
H OH
Product Side
O=
1
34
H=
42
C=
Balancing Chemical Reactions
••••• We
In
other
can
fixwords,
this
by
putting
reaction
and
more
table
Water
molecule
show
that
on
the
1front
Oxygen
left(reactant)
atom
By
counting
the
number
of
you
can
see
the
chemical
Remember,
atoms
cannot
be1atoms,
created
orbelow
destroyed
in
chemical
reactions,
group
molecules
byon
putting
coefficients
in
ofon
them:
Notice,
there
is
1the
Oxygen
atoms
left
side
and
2that
Oxygen
atoms
The
reaction
below
istogether
notin
balanced
is
created
and
1only
Hydrogen
molecule
on
the
side and
they
cansee
rearranged!
equation
ismore
balanced
andthe
shows
actual
numbers
atoms
the
right
side;
therefore
chemical
equation
is NOT of
balanced
• side
We
can
it be
is
NOT
balanced
bythe
taking
theright(product)
reactants
& products
•• The
Therefore,
table
thehas
reaction
equal
cannot
number
of
onway!
both
sides
of the
equation
The
total now
number
of
atoms
musthappen
beatoms
the this
same
on both
sides
of the
arrow
molecules
involved
in
this
reaction
apart:
2 H2
H2O + 2 H2O
H OH
H OH
Left
Reactant Side
O=
1
2
42
H=
H H
3
6
6
4
H H
O O
Right
Product Side
O=
2
24
H=
Total Number of Atoms
H+2 + O2
Subscripts and Coefficients
• When balancing chemical equations, it is important to note
that the subscripts can never change
• For example, in the equation below, the subscript of 4 in
methane cannot be changed, neither can the subscripts 2 in
Oxygen, Carbon dioxide and Water
CH4 + 2 O2
CO2 + 2H2O
• Only coefficients can be added by putting whole numbers in
front of the compounds when balancing chemical reactions
How Do we Balance Chemical Equations?
• By placing coefficients in front of each molecule
or compound
• Subscripts cannot be changed!
• Ex: CH4 + 2O2 CO2 + 2H2O
Balancing Chemical Equations
Remember: When balancing chemical equations, it is important to
note that the subscripts can never change!!!!
2
___O
___O
3
2
3
___
2 Mg + ___ O2
___
2 MgO
Practice:
Determine how many atoms of each element are in
each compound below:
1)
2)
3)
4)
2 Na + ___ Cl
___
2
4 Fe + ___
3 O
___
2
___
4 Al + ___
3 O2
2 Na + ___ F
___
2
2
___
NaCl
2 Fe O
___
2 3
___
2 Al2O3
2 NaF
___
Physical States
• In a reaction, we often use symbols to represent the physical state of
the reactants and products
• Look at the reaction below when sodium metal reacts with water:
Na(s) + H2O(l)
H2(g) + NaOH(aq)
• The symbol (s) tells us that Sodium (Na) is in the solid
state
• The symbol (l) tells us the water (H2O) is in the liquid
state
• The symbol (g) tells us the hydrogen (H2) is in the
gaseous state
• Finally, the symbol (aq) tells us that sodium hydroxide
(NaOH) is aqueous or dissolved in water
Symbol
State
(s)
solid
(l)
(g)
(aq)
liquid
gas
aqueous
What do the symbols represent in a
chemical equation?
• The symbols represent the physical state of the
reactants and products
Symbol
State
solid
Na(s) + H2O(l)
H2(g) + NaOH(aq) (s)
(l)
(g)
(aq)
liquid
gas
aqueous
or dissolved
in water
Summary
(you can always write your own summary)
• Explain the Law of Conservation of Mass in your own words
and apply it to chemical reactions:
• What is the difference between the reactants and products
in a chemical reaction?
• Describe the process of balancing chemical reactions, be
sure to explain how you count atoms on both sides of the
equation
• What can you not change when balancing chemical
reactions?
• Is the reaction below balanced? Explain why or why not:
K + Cl2 KCl
Slide 20
UNIT: Chemical Reactions
TOPIC: Properties of Reactions
Objectives: Lesson 1 of 3
•
•
•
•
To learn how we recognize a chemical reaction has took place
To learn what a chemical reactions is
To learn how we balance chemical equations
To learn the symbols for each physical state in a chemical
reaction
Quickwrite
In 1-2 sentences answer one of the questions below:
• What sort of clues do think indicate that a chemical reaction is
happening in your car engine????
• What sort of clues indicate a chemical reaction when you drop a
piece of alka selzter in water????
• What are some by products produced when your body breaks
down sugar, C6H12O6????? What are some clues that this
reaction is occuring in your body????? Hint: think of
temperature!!!!
Evidence for a Chemical Reaction
• How do you know a chemical reaction has occurred?
• Chemists look for visual clues such a color or heat
change, a solid forms, bubbles are produced, a flame
occurs
• However, reactions are not always visible
• Sometimes the only signal that a reaction is occurring is
a change in temperature as heat is produced
What are some clues that a
chemical reaction has occurred?
•
•
•
•
•
A color change
A solid forms
Bubbles form
A heat change
A flame is produced
Chemical Reactions
• Chemists have learned that a chemical change always involves a
rearrangement of the ways in which atoms are grouped and combine
with one another
• For example, consider the reaction that occurs with your laboratory
bunsen burners
• In this reaction, methane (CH4) reacts with oxygen (O2) in the air
• As you know, a flame is produce and heat is released
• As the atoms rearrange themselves, two new chemicals are produced
carbon dioxide (CO2), and water (H2O)
CH4 + O2
CO2 + H2O
Chemical
Reactions
Such a change is called a chemical reaction
•
• Notice, the atoms were rearranged, Oxygen combined with Carbon and
Hydrogen to produce 2 new chemicals: Water & Carbon Dioxide
• Chemical reactions obey the Law of Conservation of Matter which states: Atoms
cannot be destroyed, they can only be rearranged
CH4 + O2
CO2
Methane (CH4)
Water(H
Carbon
Dioxide
2O) (CO2)
Oxygen(O2)
H2O
What is a Chemical Reaction?
• A chemical reaction is the change that occurs when
atoms rearrange themselves and form new
compounds
• Chemical reactions obey the first LAW of
conservation of MASS or MATTER which states:
Atoms and matter cannot be created or destroyed,
they can only be rearranged
Chemical Equations
• We represent chemical reactions by writing a
chemical equation in which the chemicals
present before the reaction are on the left of
the arrow, and the chemicals formed by the
reaction are on the right of the arrow
• The arrow indicates the direction of the
change CH4 + O2
CO2 + H2O
Chemical Equations
• In the reaction of methane with oxygen, we have:
CH4 + O2
CO2 + H2O
Reactants
Products
• The chemicals present on the left side of the
equation are known as the reactants
• The chemicals present on the right side of the
equation are known as the products
What is a Chemical Equation?
• An equation that uses the formulas of chemicals
compounds and elements to show the reactants and
products in a chemical change
• Chemicals present before the reaction are on the left of
the arrow (reactants), and the chemicals formed by the
reaction are on the right of the arrow (products)
Ex: CH4 + O2
CO2 + H2O
Balancing Chemical Reactions
• It is important to realize that in a chemical
reaction, atoms are neither created nor
destroyed
• In other words, their must be the same
number of each type of atom on the product
side as on the reactant side of the arrow
••
•
•
•
Balancing Chemical Reactions
In
other
words,
the
reaction
and
table
below
show
Oxygen
Remember,
atoms
beatoms
created
or
destroyed
in
chemical
reactions,
We
can
fix
this
by
putting
in
1atoms,
more
Oxygen
molecule
on1inthe
left
By
the
number
you
can
see
that
the
chemical
Notice,
there
are
2cannot
Oxygen
on
left
side
and
3that
Oxygen
atoms
on
We
group
molecules
by
putting
coefficients
front
ofatom
them:
Thecounting
reaction
below
is together
notof
balanced
is
created
and
2and
Hydrogen
atoms
are
destroyed
they
can only
be
rearranged!
(reactant)
side
1 more
Water
molecule
on
theleft
right
(product)
side
the
right
side;
4byHydrogen
the
side
and 2 apart:
equation
is
balanced
andare
shows
the
actual
numbers
molecules
We can
see
it isalso
notthere
balanced
taking
theonreactants
&ofproducts
Therefore,
the
reaction
cannot
way!
total in
number
of
atoms
musthappen
be
thethis
same
on both
sides
of the
arrow
The
table
now
has
equal
number
of atoms
on
both
sides
of the
equation
Hydrogen
on
the
right
side
involved
this
reaction
CH4
O+2 +2 O2
CO2
H+2+O +2H2O
H
H CH
H
O O
O C O
H OH
O O
Left
Reactant Side
C=
O=
1
2
4
H=
4
9
7
6
9
Total Number of Atoms
Right
H OH
Product Side
O=
1
34
H=
42
C=
Balancing Chemical Reactions
••••• We
In
other
can
fixwords,
this
by
putting
reaction
and
more
table
Water
molecule
show
that
on
the
1front
Oxygen
left(reactant)
atom
By
counting
the
number
of
you
can
see
the
chemical
Remember,
atoms
cannot
be1atoms,
created
orbelow
destroyed
in
chemical
reactions,
group
molecules
byon
putting
coefficients
in
ofon
them:
Notice,
there
is
1the
Oxygen
atoms
left
side
and
2that
Oxygen
atoms
The
reaction
below
istogether
notin
balanced
is
created
and
1only
Hydrogen
molecule
on
the
side and
they
cansee
rearranged!
equation
ismore
balanced
andthe
shows
actual
numbers
atoms
the
right
side;
therefore
chemical
equation
is NOT of
balanced
• side
We
can
it be
is
NOT
balanced
bythe
taking
theright(product)
reactants
& products
•• The
Therefore,
table
thehas
reaction
equal
cannot
number
of
onway!
both
sides
of the
equation
The
total now
number
of
atoms
musthappen
beatoms
the this
same
on both
sides
of the
arrow
molecules
involved
in
this
reaction
apart:
2 H2
H2O + 2 H2O
H OH
H OH
Left
Reactant Side
O=
1
2
42
H=
H H
3
6
6
4
H H
O O
Right
Product Side
O=
2
24
H=
Total Number of Atoms
H+2 + O2
Subscripts and Coefficients
• When balancing chemical equations, it is important to note
that the subscripts can never change
• For example, in the equation below, the subscript of 4 in
methane cannot be changed, neither can the subscripts 2 in
Oxygen, Carbon dioxide and Water
CH4 + 2 O2
CO2 + 2H2O
• Only coefficients can be added by putting whole numbers in
front of the compounds when balancing chemical reactions
How Do we Balance Chemical Equations?
• By placing coefficients in front of each molecule
or compound
• Subscripts cannot be changed!
• Ex: CH4 + 2O2 CO2 + 2H2O
Balancing Chemical Equations
Remember: When balancing chemical equations, it is important to
note that the subscripts can never change!!!!
2
___O
___O
3
2
3
___
2 Mg + ___ O2
___
2 MgO
Practice:
Determine how many atoms of each element are in
each compound below:
1)
2)
3)
4)
2 Na + ___ Cl
___
2
4 Fe + ___
3 O
___
2
___
4 Al + ___
3 O2
2 Na + ___ F
___
2
2
___
NaCl
2 Fe O
___
2 3
___
2 Al2O3
2 NaF
___
Physical States
• In a reaction, we often use symbols to represent the physical state of
the reactants and products
• Look at the reaction below when sodium metal reacts with water:
Na(s) + H2O(l)
H2(g) + NaOH(aq)
• The symbol (s) tells us that Sodium (Na) is in the solid
state
• The symbol (l) tells us the water (H2O) is in the liquid
state
• The symbol (g) tells us the hydrogen (H2) is in the
gaseous state
• Finally, the symbol (aq) tells us that sodium hydroxide
(NaOH) is aqueous or dissolved in water
Symbol
State
(s)
solid
(l)
(g)
(aq)
liquid
gas
aqueous
What do the symbols represent in a
chemical equation?
• The symbols represent the physical state of the
reactants and products
Symbol
State
solid
Na(s) + H2O(l)
H2(g) + NaOH(aq) (s)
(l)
(g)
(aq)
liquid
gas
aqueous
or dissolved
in water
Summary
(you can always write your own summary)
• Explain the Law of Conservation of Mass in your own words
and apply it to chemical reactions:
• What is the difference between the reactants and products
in a chemical reaction?
• Describe the process of balancing chemical reactions, be
sure to explain how you count atoms on both sides of the
equation
• What can you not change when balancing chemical
reactions?
• Is the reaction below balanced? Explain why or why not:
K + Cl2 KCl
UNIT: Chemical Reactions
TOPIC: Properties of Reactions
Objectives: Lesson 1 of 3
•
•
•
•
To learn how we recognize a chemical reaction has took place
To learn what a chemical reactions is
To learn how we balance chemical equations
To learn the symbols for each physical state in a chemical
reaction
Quickwrite
In 1-2 sentences answer one of the questions below:
• What sort of clues do think indicate that a chemical reaction is
happening in your car engine????
• What sort of clues indicate a chemical reaction when you drop a
piece of alka selzter in water????
• What are some by products produced when your body breaks
down sugar, C6H12O6????? What are some clues that this
reaction is occuring in your body????? Hint: think of
temperature!!!!
Evidence for a Chemical Reaction
• How do you know a chemical reaction has occurred?
• Chemists look for visual clues such a color or heat
change, a solid forms, bubbles are produced, a flame
occurs
• However, reactions are not always visible
• Sometimes the only signal that a reaction is occurring is
a change in temperature as heat is produced
What are some clues that a
chemical reaction has occurred?
•
•
•
•
•
A color change
A solid forms
Bubbles form
A heat change
A flame is produced
Chemical Reactions
• Chemists have learned that a chemical change always involves a
rearrangement of the ways in which atoms are grouped and combine
with one another
• For example, consider the reaction that occurs with your laboratory
bunsen burners
• In this reaction, methane (CH4) reacts with oxygen (O2) in the air
• As you know, a flame is produce and heat is released
• As the atoms rearrange themselves, two new chemicals are produced
carbon dioxide (CO2), and water (H2O)
CH4 + O2
CO2 + H2O
Chemical
Reactions
Such a change is called a chemical reaction
•
• Notice, the atoms were rearranged, Oxygen combined with Carbon and
Hydrogen to produce 2 new chemicals: Water & Carbon Dioxide
• Chemical reactions obey the Law of Conservation of Matter which states: Atoms
cannot be destroyed, they can only be rearranged
CH4 + O2
CO2
Methane (CH4)
Water(H
Carbon
Dioxide
2O) (CO2)
Oxygen(O2)
H2O
What is a Chemical Reaction?
• A chemical reaction is the change that occurs when
atoms rearrange themselves and form new
compounds
• Chemical reactions obey the first LAW of
conservation of MASS or MATTER which states:
Atoms and matter cannot be created or destroyed,
they can only be rearranged
Chemical Equations
• We represent chemical reactions by writing a
chemical equation in which the chemicals
present before the reaction are on the left of
the arrow, and the chemicals formed by the
reaction are on the right of the arrow
• The arrow indicates the direction of the
change CH4 + O2
CO2 + H2O
Chemical Equations
• In the reaction of methane with oxygen, we have:
CH4 + O2
CO2 + H2O
Reactants
Products
• The chemicals present on the left side of the
equation are known as the reactants
• The chemicals present on the right side of the
equation are known as the products
What is a Chemical Equation?
• An equation that uses the formulas of chemicals
compounds and elements to show the reactants and
products in a chemical change
• Chemicals present before the reaction are on the left of
the arrow (reactants), and the chemicals formed by the
reaction are on the right of the arrow (products)
Ex: CH4 + O2
CO2 + H2O
Balancing Chemical Reactions
• It is important to realize that in a chemical
reaction, atoms are neither created nor
destroyed
• In other words, their must be the same
number of each type of atom on the product
side as on the reactant side of the arrow
••
•
•
•
Balancing Chemical Reactions
In
other
words,
the
reaction
and
table
below
show
Oxygen
Remember,
atoms
beatoms
created
or
destroyed
in
chemical
reactions,
We
can
fix
this
by
putting
in
1atoms,
more
Oxygen
molecule
on1inthe
left
By
the
number
you
can
see
that
the
chemical
Notice,
there
are
2cannot
Oxygen
on
left
side
and
3that
Oxygen
atoms
on
We
group
molecules
by
putting
coefficients
front
ofatom
them:
Thecounting
reaction
below
is together
notof
balanced
is
created
and
2and
Hydrogen
atoms
are
destroyed
they
can only
be
rearranged!
(reactant)
side
1 more
Water
molecule
on
theleft
right
(product)
side
the
right
side;
4byHydrogen
the
side
and 2 apart:
equation
is
balanced
andare
shows
the
actual
numbers
molecules
We can
see
it isalso
notthere
balanced
taking
theonreactants
&ofproducts
Therefore,
the
reaction
cannot
way!
total in
number
of
atoms
musthappen
be
thethis
same
on both
sides
of the
arrow
The
table
now
has
equal
number
of atoms
on
both
sides
of the
equation
Hydrogen
on
the
right
side
involved
this
reaction
CH4
O+2 +2 O2
CO2
H+2+O +2H2O
H
H CH
H
O O
O C O
H OH
O O
Left
Reactant Side
C=
O=
1
2
4
H=
4
9
7
6
9
Total Number of Atoms
Right
H OH
Product Side
O=
1
34
H=
42
C=
Balancing Chemical Reactions
••••• We
In
other
can
fixwords,
this
by
putting
reaction
and
more
table
Water
molecule
show
that
on
the
1front
Oxygen
left(reactant)
atom
By
counting
the
number
of
you
can
see
the
chemical
Remember,
atoms
cannot
be1atoms,
created
orbelow
destroyed
in
chemical
reactions,
group
molecules
byon
putting
coefficients
in
ofon
them:
Notice,
there
is
1the
Oxygen
atoms
left
side
and
2that
Oxygen
atoms
The
reaction
below
istogether
notin
balanced
is
created
and
1only
Hydrogen
molecule
on
the
side and
they
cansee
rearranged!
equation
ismore
balanced
andthe
shows
actual
numbers
atoms
the
right
side;
therefore
chemical
equation
is NOT of
balanced
• side
We
can
it be
is
NOT
balanced
bythe
taking
theright(product)
reactants
& products
•• The
Therefore,
table
thehas
reaction
equal
cannot
number
of
onway!
both
sides
of the
equation
The
total now
number
of
atoms
musthappen
beatoms
the this
same
on both
sides
of the
arrow
molecules
involved
in
this
reaction
apart:
2 H2
H2O + 2 H2O
H OH
H OH
Left
Reactant Side
O=
1
2
42
H=
H H
3
6
6
4
H H
O O
Right
Product Side
O=
2
24
H=
Total Number of Atoms
H+2 + O2
Subscripts and Coefficients
• When balancing chemical equations, it is important to note
that the subscripts can never change
• For example, in the equation below, the subscript of 4 in
methane cannot be changed, neither can the subscripts 2 in
Oxygen, Carbon dioxide and Water
CH4 + 2 O2
CO2 + 2H2O
• Only coefficients can be added by putting whole numbers in
front of the compounds when balancing chemical reactions
How Do we Balance Chemical Equations?
• By placing coefficients in front of each molecule
or compound
• Subscripts cannot be changed!
• Ex: CH4 + 2O2 CO2 + 2H2O
Balancing Chemical Equations
Remember: When balancing chemical equations, it is important to
note that the subscripts can never change!!!!
2
___O
___O
3
2
3
___
2 Mg + ___ O2
___
2 MgO
Practice:
Determine how many atoms of each element are in
each compound below:
1)
2)
3)
4)
2 Na + ___ Cl
___
2
4 Fe + ___
3 O
___
2
___
4 Al + ___
3 O2
2 Na + ___ F
___
2
2
___
NaCl
2 Fe O
___
2 3
___
2 Al2O3
2 NaF
___
Physical States
• In a reaction, we often use symbols to represent the physical state of
the reactants and products
• Look at the reaction below when sodium metal reacts with water:
Na(s) + H2O(l)
H2(g) + NaOH(aq)
• The symbol (s) tells us that Sodium (Na) is in the solid
state
• The symbol (l) tells us the water (H2O) is in the liquid
state
• The symbol (g) tells us the hydrogen (H2) is in the
gaseous state
• Finally, the symbol (aq) tells us that sodium hydroxide
(NaOH) is aqueous or dissolved in water
Symbol
State
(s)
solid
(l)
(g)
(aq)
liquid
gas
aqueous
What do the symbols represent in a
chemical equation?
• The symbols represent the physical state of the
reactants and products
Symbol
State
solid
Na(s) + H2O(l)
H2(g) + NaOH(aq) (s)
(l)
(g)
(aq)
liquid
gas
aqueous
or dissolved
in water
Summary
(you can always write your own summary)
• Explain the Law of Conservation of Mass in your own words
and apply it to chemical reactions:
• What is the difference between the reactants and products
in a chemical reaction?
• Describe the process of balancing chemical reactions, be
sure to explain how you count atoms on both sides of the
equation
• What can you not change when balancing chemical
reactions?
• Is the reaction below balanced? Explain why or why not:
K + Cl2 KCl
Slide 2
UNIT: Chemical Reactions
TOPIC: Properties of Reactions
Objectives: Lesson 1 of 3
•
•
•
•
To learn how we recognize a chemical reaction has took place
To learn what a chemical reactions is
To learn how we balance chemical equations
To learn the symbols for each physical state in a chemical
reaction
Quickwrite
In 1-2 sentences answer one of the questions below:
• What sort of clues do think indicate that a chemical reaction is
happening in your car engine????
• What sort of clues indicate a chemical reaction when you drop a
piece of alka selzter in water????
• What are some by products produced when your body breaks
down sugar, C6H12O6????? What are some clues that this
reaction is occuring in your body????? Hint: think of
temperature!!!!
Evidence for a Chemical Reaction
• How do you know a chemical reaction has occurred?
• Chemists look for visual clues such a color or heat
change, a solid forms, bubbles are produced, a flame
occurs
• However, reactions are not always visible
• Sometimes the only signal that a reaction is occurring is
a change in temperature as heat is produced
What are some clues that a
chemical reaction has occurred?
•
•
•
•
•
A color change
A solid forms
Bubbles form
A heat change
A flame is produced
Chemical Reactions
• Chemists have learned that a chemical change always involves a
rearrangement of the ways in which atoms are grouped and combine
with one another
• For example, consider the reaction that occurs with your laboratory
bunsen burners
• In this reaction, methane (CH4) reacts with oxygen (O2) in the air
• As you know, a flame is produce and heat is released
• As the atoms rearrange themselves, two new chemicals are produced
carbon dioxide (CO2), and water (H2O)
CH4 + O2
CO2 + H2O
Chemical
Reactions
Such a change is called a chemical reaction
•
• Notice, the atoms were rearranged, Oxygen combined with Carbon and
Hydrogen to produce 2 new chemicals: Water & Carbon Dioxide
• Chemical reactions obey the Law of Conservation of Matter which states: Atoms
cannot be destroyed, they can only be rearranged
CH4 + O2
CO2
Methane (CH4)
Water(H
Carbon
Dioxide
2O) (CO2)
Oxygen(O2)
H2O
What is a Chemical Reaction?
• A chemical reaction is the change that occurs when
atoms rearrange themselves and form new
compounds
• Chemical reactions obey the first LAW of
conservation of MASS or MATTER which states:
Atoms and matter cannot be created or destroyed,
they can only be rearranged
Chemical Equations
• We represent chemical reactions by writing a
chemical equation in which the chemicals
present before the reaction are on the left of
the arrow, and the chemicals formed by the
reaction are on the right of the arrow
• The arrow indicates the direction of the
change CH4 + O2
CO2 + H2O
Chemical Equations
• In the reaction of methane with oxygen, we have:
CH4 + O2
CO2 + H2O
Reactants
Products
• The chemicals present on the left side of the
equation are known as the reactants
• The chemicals present on the right side of the
equation are known as the products
What is a Chemical Equation?
• An equation that uses the formulas of chemicals
compounds and elements to show the reactants and
products in a chemical change
• Chemicals present before the reaction are on the left of
the arrow (reactants), and the chemicals formed by the
reaction are on the right of the arrow (products)
Ex: CH4 + O2
CO2 + H2O
Balancing Chemical Reactions
• It is important to realize that in a chemical
reaction, atoms are neither created nor
destroyed
• In other words, their must be the same
number of each type of atom on the product
side as on the reactant side of the arrow
••
•
•
•
Balancing Chemical Reactions
In
other
words,
the
reaction
and
table
below
show
Oxygen
Remember,
atoms
beatoms
created
or
destroyed
in
chemical
reactions,
We
can
fix
this
by
putting
in
1atoms,
more
Oxygen
molecule
on1inthe
left
By
the
number
you
can
see
that
the
chemical
Notice,
there
are
2cannot
Oxygen
on
left
side
and
3that
Oxygen
atoms
on
We
group
molecules
by
putting
coefficients
front
ofatom
them:
Thecounting
reaction
below
is together
notof
balanced
is
created
and
2and
Hydrogen
atoms
are
destroyed
they
can only
be
rearranged!
(reactant)
side
1 more
Water
molecule
on
theleft
right
(product)
side
the
right
side;
4byHydrogen
the
side
and 2 apart:
equation
is
balanced
andare
shows
the
actual
numbers
molecules
We can
see
it isalso
notthere
balanced
taking
theonreactants
&ofproducts
Therefore,
the
reaction
cannot
way!
total in
number
of
atoms
musthappen
be
thethis
same
on both
sides
of the
arrow
The
table
now
has
equal
number
of atoms
on
both
sides
of the
equation
Hydrogen
on
the
right
side
involved
this
reaction
CH4
O+2 +2 O2
CO2
H+2+O +2H2O
H
H CH
H
O O
O C O
H OH
O O
Left
Reactant Side
C=
O=
1
2
4
H=
4
9
7
6
9
Total Number of Atoms
Right
H OH
Product Side
O=
1
34
H=
42
C=
Balancing Chemical Reactions
••••• We
In
other
can
fixwords,
this
by
putting
reaction
and
more
table
Water
molecule
show
that
on
the
1front
Oxygen
left(reactant)
atom
By
counting
the
number
of
you
can
see
the
chemical
Remember,
atoms
cannot
be1atoms,
created
orbelow
destroyed
in
chemical
reactions,
group
molecules
byon
putting
coefficients
in
ofon
them:
Notice,
there
is
1the
Oxygen
atoms
left
side
and
2that
Oxygen
atoms
The
reaction
below
istogether
notin
balanced
is
created
and
1only
Hydrogen
molecule
on
the
side and
they
cansee
rearranged!
equation
ismore
balanced
andthe
shows
actual
numbers
atoms
the
right
side;
therefore
chemical
equation
is NOT of
balanced
• side
We
can
it be
is
NOT
balanced
bythe
taking
theright(product)
reactants
& products
•• The
Therefore,
table
thehas
reaction
equal
cannot
number
of
onway!
both
sides
of the
equation
The
total now
number
of
atoms
musthappen
beatoms
the this
same
on both
sides
of the
arrow
molecules
involved
in
this
reaction
apart:
2 H2
H2O + 2 H2O
H OH
H OH
Left
Reactant Side
O=
1
2
42
H=
H H
3
6
6
4
H H
O O
Right
Product Side
O=
2
24
H=
Total Number of Atoms
H+2 + O2
Subscripts and Coefficients
• When balancing chemical equations, it is important to note
that the subscripts can never change
• For example, in the equation below, the subscript of 4 in
methane cannot be changed, neither can the subscripts 2 in
Oxygen, Carbon dioxide and Water
CH4 + 2 O2
CO2 + 2H2O
• Only coefficients can be added by putting whole numbers in
front of the compounds when balancing chemical reactions
How Do we Balance Chemical Equations?
• By placing coefficients in front of each molecule
or compound
• Subscripts cannot be changed!
• Ex: CH4 + 2O2 CO2 + 2H2O
Balancing Chemical Equations
Remember: When balancing chemical equations, it is important to
note that the subscripts can never change!!!!
2
___O
___O
3
2
3
___
2 Mg + ___ O2
___
2 MgO
Practice:
Determine how many atoms of each element are in
each compound below:
1)
2)
3)
4)
2 Na + ___ Cl
___
2
4 Fe + ___
3 O
___
2
___
4 Al + ___
3 O2
2 Na + ___ F
___
2
2
___
NaCl
2 Fe O
___
2 3
___
2 Al2O3
2 NaF
___
Physical States
• In a reaction, we often use symbols to represent the physical state of
the reactants and products
• Look at the reaction below when sodium metal reacts with water:
Na(s) + H2O(l)
H2(g) + NaOH(aq)
• The symbol (s) tells us that Sodium (Na) is in the solid
state
• The symbol (l) tells us the water (H2O) is in the liquid
state
• The symbol (g) tells us the hydrogen (H2) is in the
gaseous state
• Finally, the symbol (aq) tells us that sodium hydroxide
(NaOH) is aqueous or dissolved in water
Symbol
State
(s)
solid
(l)
(g)
(aq)
liquid
gas
aqueous
What do the symbols represent in a
chemical equation?
• The symbols represent the physical state of the
reactants and products
Symbol
State
solid
Na(s) + H2O(l)
H2(g) + NaOH(aq) (s)
(l)
(g)
(aq)
liquid
gas
aqueous
or dissolved
in water
Summary
(you can always write your own summary)
• Explain the Law of Conservation of Mass in your own words
and apply it to chemical reactions:
• What is the difference between the reactants and products
in a chemical reaction?
• Describe the process of balancing chemical reactions, be
sure to explain how you count atoms on both sides of the
equation
• What can you not change when balancing chemical
reactions?
• Is the reaction below balanced? Explain why or why not:
K + Cl2 KCl
Slide 3
UNIT: Chemical Reactions
TOPIC: Properties of Reactions
Objectives: Lesson 1 of 3
•
•
•
•
To learn how we recognize a chemical reaction has took place
To learn what a chemical reactions is
To learn how we balance chemical equations
To learn the symbols for each physical state in a chemical
reaction
Quickwrite
In 1-2 sentences answer one of the questions below:
• What sort of clues do think indicate that a chemical reaction is
happening in your car engine????
• What sort of clues indicate a chemical reaction when you drop a
piece of alka selzter in water????
• What are some by products produced when your body breaks
down sugar, C6H12O6????? What are some clues that this
reaction is occuring in your body????? Hint: think of
temperature!!!!
Evidence for a Chemical Reaction
• How do you know a chemical reaction has occurred?
• Chemists look for visual clues such a color or heat
change, a solid forms, bubbles are produced, a flame
occurs
• However, reactions are not always visible
• Sometimes the only signal that a reaction is occurring is
a change in temperature as heat is produced
What are some clues that a
chemical reaction has occurred?
•
•
•
•
•
A color change
A solid forms
Bubbles form
A heat change
A flame is produced
Chemical Reactions
• Chemists have learned that a chemical change always involves a
rearrangement of the ways in which atoms are grouped and combine
with one another
• For example, consider the reaction that occurs with your laboratory
bunsen burners
• In this reaction, methane (CH4) reacts with oxygen (O2) in the air
• As you know, a flame is produce and heat is released
• As the atoms rearrange themselves, two new chemicals are produced
carbon dioxide (CO2), and water (H2O)
CH4 + O2
CO2 + H2O
Chemical
Reactions
Such a change is called a chemical reaction
•
• Notice, the atoms were rearranged, Oxygen combined with Carbon and
Hydrogen to produce 2 new chemicals: Water & Carbon Dioxide
• Chemical reactions obey the Law of Conservation of Matter which states: Atoms
cannot be destroyed, they can only be rearranged
CH4 + O2
CO2
Methane (CH4)
Water(H
Carbon
Dioxide
2O) (CO2)
Oxygen(O2)
H2O
What is a Chemical Reaction?
• A chemical reaction is the change that occurs when
atoms rearrange themselves and form new
compounds
• Chemical reactions obey the first LAW of
conservation of MASS or MATTER which states:
Atoms and matter cannot be created or destroyed,
they can only be rearranged
Chemical Equations
• We represent chemical reactions by writing a
chemical equation in which the chemicals
present before the reaction are on the left of
the arrow, and the chemicals formed by the
reaction are on the right of the arrow
• The arrow indicates the direction of the
change CH4 + O2
CO2 + H2O
Chemical Equations
• In the reaction of methane with oxygen, we have:
CH4 + O2
CO2 + H2O
Reactants
Products
• The chemicals present on the left side of the
equation are known as the reactants
• The chemicals present on the right side of the
equation are known as the products
What is a Chemical Equation?
• An equation that uses the formulas of chemicals
compounds and elements to show the reactants and
products in a chemical change
• Chemicals present before the reaction are on the left of
the arrow (reactants), and the chemicals formed by the
reaction are on the right of the arrow (products)
Ex: CH4 + O2
CO2 + H2O
Balancing Chemical Reactions
• It is important to realize that in a chemical
reaction, atoms are neither created nor
destroyed
• In other words, their must be the same
number of each type of atom on the product
side as on the reactant side of the arrow
••
•
•
•
Balancing Chemical Reactions
In
other
words,
the
reaction
and
table
below
show
Oxygen
Remember,
atoms
beatoms
created
or
destroyed
in
chemical
reactions,
We
can
fix
this
by
putting
in
1atoms,
more
Oxygen
molecule
on1inthe
left
By
the
number
you
can
see
that
the
chemical
Notice,
there
are
2cannot
Oxygen
on
left
side
and
3that
Oxygen
atoms
on
We
group
molecules
by
putting
coefficients
front
ofatom
them:
Thecounting
reaction
below
is together
notof
balanced
is
created
and
2and
Hydrogen
atoms
are
destroyed
they
can only
be
rearranged!
(reactant)
side
1 more
Water
molecule
on
theleft
right
(product)
side
the
right
side;
4byHydrogen
the
side
and 2 apart:
equation
is
balanced
andare
shows
the
actual
numbers
molecules
We can
see
it isalso
notthere
balanced
taking
theonreactants
&ofproducts
Therefore,
the
reaction
cannot
way!
total in
number
of
atoms
musthappen
be
thethis
same
on both
sides
of the
arrow
The
table
now
has
equal
number
of atoms
on
both
sides
of the
equation
Hydrogen
on
the
right
side
involved
this
reaction
CH4
O+2 +2 O2
CO2
H+2+O +2H2O
H
H CH
H
O O
O C O
H OH
O O
Left
Reactant Side
C=
O=
1
2
4
H=
4
9
7
6
9
Total Number of Atoms
Right
H OH
Product Side
O=
1
34
H=
42
C=
Balancing Chemical Reactions
••••• We
In
other
can
fixwords,
this
by
putting
reaction
and
more
table
Water
molecule
show
that
on
the
1front
Oxygen
left(reactant)
atom
By
counting
the
number
of
you
can
see
the
chemical
Remember,
atoms
cannot
be1atoms,
created
orbelow
destroyed
in
chemical
reactions,
group
molecules
byon
putting
coefficients
in
ofon
them:
Notice,
there
is
1the
Oxygen
atoms
left
side
and
2that
Oxygen
atoms
The
reaction
below
istogether
notin
balanced
is
created
and
1only
Hydrogen
molecule
on
the
side and
they
cansee
rearranged!
equation
ismore
balanced
andthe
shows
actual
numbers
atoms
the
right
side;
therefore
chemical
equation
is NOT of
balanced
• side
We
can
it be
is
NOT
balanced
bythe
taking
theright(product)
reactants
& products
•• The
Therefore,
table
thehas
reaction
equal
cannot
number
of
onway!
both
sides
of the
equation
The
total now
number
of
atoms
musthappen
beatoms
the this
same
on both
sides
of the
arrow
molecules
involved
in
this
reaction
apart:
2 H2
H2O + 2 H2O
H OH
H OH
Left
Reactant Side
O=
1
2
42
H=
H H
3
6
6
4
H H
O O
Right
Product Side
O=
2
24
H=
Total Number of Atoms
H+2 + O2
Subscripts and Coefficients
• When balancing chemical equations, it is important to note
that the subscripts can never change
• For example, in the equation below, the subscript of 4 in
methane cannot be changed, neither can the subscripts 2 in
Oxygen, Carbon dioxide and Water
CH4 + 2 O2
CO2 + 2H2O
• Only coefficients can be added by putting whole numbers in
front of the compounds when balancing chemical reactions
How Do we Balance Chemical Equations?
• By placing coefficients in front of each molecule
or compound
• Subscripts cannot be changed!
• Ex: CH4 + 2O2 CO2 + 2H2O
Balancing Chemical Equations
Remember: When balancing chemical equations, it is important to
note that the subscripts can never change!!!!
2
___O
___O
3
2
3
___
2 Mg + ___ O2
___
2 MgO
Practice:
Determine how many atoms of each element are in
each compound below:
1)
2)
3)
4)
2 Na + ___ Cl
___
2
4 Fe + ___
3 O
___
2
___
4 Al + ___
3 O2
2 Na + ___ F
___
2
2
___
NaCl
2 Fe O
___
2 3
___
2 Al2O3
2 NaF
___
Physical States
• In a reaction, we often use symbols to represent the physical state of
the reactants and products
• Look at the reaction below when sodium metal reacts with water:
Na(s) + H2O(l)
H2(g) + NaOH(aq)
• The symbol (s) tells us that Sodium (Na) is in the solid
state
• The symbol (l) tells us the water (H2O) is in the liquid
state
• The symbol (g) tells us the hydrogen (H2) is in the
gaseous state
• Finally, the symbol (aq) tells us that sodium hydroxide
(NaOH) is aqueous or dissolved in water
Symbol
State
(s)
solid
(l)
(g)
(aq)
liquid
gas
aqueous
What do the symbols represent in a
chemical equation?
• The symbols represent the physical state of the
reactants and products
Symbol
State
solid
Na(s) + H2O(l)
H2(g) + NaOH(aq) (s)
(l)
(g)
(aq)
liquid
gas
aqueous
or dissolved
in water
Summary
(you can always write your own summary)
• Explain the Law of Conservation of Mass in your own words
and apply it to chemical reactions:
• What is the difference between the reactants and products
in a chemical reaction?
• Describe the process of balancing chemical reactions, be
sure to explain how you count atoms on both sides of the
equation
• What can you not change when balancing chemical
reactions?
• Is the reaction below balanced? Explain why or why not:
K + Cl2 KCl
Slide 4
UNIT: Chemical Reactions
TOPIC: Properties of Reactions
Objectives: Lesson 1 of 3
•
•
•
•
To learn how we recognize a chemical reaction has took place
To learn what a chemical reactions is
To learn how we balance chemical equations
To learn the symbols for each physical state in a chemical
reaction
Quickwrite
In 1-2 sentences answer one of the questions below:
• What sort of clues do think indicate that a chemical reaction is
happening in your car engine????
• What sort of clues indicate a chemical reaction when you drop a
piece of alka selzter in water????
• What are some by products produced when your body breaks
down sugar, C6H12O6????? What are some clues that this
reaction is occuring in your body????? Hint: think of
temperature!!!!
Evidence for a Chemical Reaction
• How do you know a chemical reaction has occurred?
• Chemists look for visual clues such a color or heat
change, a solid forms, bubbles are produced, a flame
occurs
• However, reactions are not always visible
• Sometimes the only signal that a reaction is occurring is
a change in temperature as heat is produced
What are some clues that a
chemical reaction has occurred?
•
•
•
•
•
A color change
A solid forms
Bubbles form
A heat change
A flame is produced
Chemical Reactions
• Chemists have learned that a chemical change always involves a
rearrangement of the ways in which atoms are grouped and combine
with one another
• For example, consider the reaction that occurs with your laboratory
bunsen burners
• In this reaction, methane (CH4) reacts with oxygen (O2) in the air
• As you know, a flame is produce and heat is released
• As the atoms rearrange themselves, two new chemicals are produced
carbon dioxide (CO2), and water (H2O)
CH4 + O2
CO2 + H2O
Chemical
Reactions
Such a change is called a chemical reaction
•
• Notice, the atoms were rearranged, Oxygen combined with Carbon and
Hydrogen to produce 2 new chemicals: Water & Carbon Dioxide
• Chemical reactions obey the Law of Conservation of Matter which states: Atoms
cannot be destroyed, they can only be rearranged
CH4 + O2
CO2
Methane (CH4)
Water(H
Carbon
Dioxide
2O) (CO2)
Oxygen(O2)
H2O
What is a Chemical Reaction?
• A chemical reaction is the change that occurs when
atoms rearrange themselves and form new
compounds
• Chemical reactions obey the first LAW of
conservation of MASS or MATTER which states:
Atoms and matter cannot be created or destroyed,
they can only be rearranged
Chemical Equations
• We represent chemical reactions by writing a
chemical equation in which the chemicals
present before the reaction are on the left of
the arrow, and the chemicals formed by the
reaction are on the right of the arrow
• The arrow indicates the direction of the
change CH4 + O2
CO2 + H2O
Chemical Equations
• In the reaction of methane with oxygen, we have:
CH4 + O2
CO2 + H2O
Reactants
Products
• The chemicals present on the left side of the
equation are known as the reactants
• The chemicals present on the right side of the
equation are known as the products
What is a Chemical Equation?
• An equation that uses the formulas of chemicals
compounds and elements to show the reactants and
products in a chemical change
• Chemicals present before the reaction are on the left of
the arrow (reactants), and the chemicals formed by the
reaction are on the right of the arrow (products)
Ex: CH4 + O2
CO2 + H2O
Balancing Chemical Reactions
• It is important to realize that in a chemical
reaction, atoms are neither created nor
destroyed
• In other words, their must be the same
number of each type of atom on the product
side as on the reactant side of the arrow
••
•
•
•
Balancing Chemical Reactions
In
other
words,
the
reaction
and
table
below
show
Oxygen
Remember,
atoms
beatoms
created
or
destroyed
in
chemical
reactions,
We
can
fix
this
by
putting
in
1atoms,
more
Oxygen
molecule
on1inthe
left
By
the
number
you
can
see
that
the
chemical
Notice,
there
are
2cannot
Oxygen
on
left
side
and
3that
Oxygen
atoms
on
We
group
molecules
by
putting
coefficients
front
ofatom
them:
Thecounting
reaction
below
is together
notof
balanced
is
created
and
2and
Hydrogen
atoms
are
destroyed
they
can only
be
rearranged!
(reactant)
side
1 more
Water
molecule
on
theleft
right
(product)
side
the
right
side;
4byHydrogen
the
side
and 2 apart:
equation
is
balanced
andare
shows
the
actual
numbers
molecules
We can
see
it isalso
notthere
balanced
taking
theonreactants
&ofproducts
Therefore,
the
reaction
cannot
way!
total in
number
of
atoms
musthappen
be
thethis
same
on both
sides
of the
arrow
The
table
now
has
equal
number
of atoms
on
both
sides
of the
equation
Hydrogen
on
the
right
side
involved
this
reaction
CH4
O+2 +2 O2
CO2
H+2+O +2H2O
H
H CH
H
O O
O C O
H OH
O O
Left
Reactant Side
C=
O=
1
2
4
H=
4
9
7
6
9
Total Number of Atoms
Right
H OH
Product Side
O=
1
34
H=
42
C=
Balancing Chemical Reactions
••••• We
In
other
can
fixwords,
this
by
putting
reaction
and
more
table
Water
molecule
show
that
on
the
1front
Oxygen
left(reactant)
atom
By
counting
the
number
of
you
can
see
the
chemical
Remember,
atoms
cannot
be1atoms,
created
orbelow
destroyed
in
chemical
reactions,
group
molecules
byon
putting
coefficients
in
ofon
them:
Notice,
there
is
1the
Oxygen
atoms
left
side
and
2that
Oxygen
atoms
The
reaction
below
istogether
notin
balanced
is
created
and
1only
Hydrogen
molecule
on
the
side and
they
cansee
rearranged!
equation
ismore
balanced
andthe
shows
actual
numbers
atoms
the
right
side;
therefore
chemical
equation
is NOT of
balanced
• side
We
can
it be
is
NOT
balanced
bythe
taking
theright(product)
reactants
& products
•• The
Therefore,
table
thehas
reaction
equal
cannot
number
of
onway!
both
sides
of the
equation
The
total now
number
of
atoms
musthappen
beatoms
the this
same
on both
sides
of the
arrow
molecules
involved
in
this
reaction
apart:
2 H2
H2O + 2 H2O
H OH
H OH
Left
Reactant Side
O=
1
2
42
H=
H H
3
6
6
4
H H
O O
Right
Product Side
O=
2
24
H=
Total Number of Atoms
H+2 + O2
Subscripts and Coefficients
• When balancing chemical equations, it is important to note
that the subscripts can never change
• For example, in the equation below, the subscript of 4 in
methane cannot be changed, neither can the subscripts 2 in
Oxygen, Carbon dioxide and Water
CH4 + 2 O2
CO2 + 2H2O
• Only coefficients can be added by putting whole numbers in
front of the compounds when balancing chemical reactions
How Do we Balance Chemical Equations?
• By placing coefficients in front of each molecule
or compound
• Subscripts cannot be changed!
• Ex: CH4 + 2O2 CO2 + 2H2O
Balancing Chemical Equations
Remember: When balancing chemical equations, it is important to
note that the subscripts can never change!!!!
2
___O
___O
3
2
3
___
2 Mg + ___ O2
___
2 MgO
Practice:
Determine how many atoms of each element are in
each compound below:
1)
2)
3)
4)
2 Na + ___ Cl
___
2
4 Fe + ___
3 O
___
2
___
4 Al + ___
3 O2
2 Na + ___ F
___
2
2
___
NaCl
2 Fe O
___
2 3
___
2 Al2O3
2 NaF
___
Physical States
• In a reaction, we often use symbols to represent the physical state of
the reactants and products
• Look at the reaction below when sodium metal reacts with water:
Na(s) + H2O(l)
H2(g) + NaOH(aq)
• The symbol (s) tells us that Sodium (Na) is in the solid
state
• The symbol (l) tells us the water (H2O) is in the liquid
state
• The symbol (g) tells us the hydrogen (H2) is in the
gaseous state
• Finally, the symbol (aq) tells us that sodium hydroxide
(NaOH) is aqueous or dissolved in water
Symbol
State
(s)
solid
(l)
(g)
(aq)
liquid
gas
aqueous
What do the symbols represent in a
chemical equation?
• The symbols represent the physical state of the
reactants and products
Symbol
State
solid
Na(s) + H2O(l)
H2(g) + NaOH(aq) (s)
(l)
(g)
(aq)
liquid
gas
aqueous
or dissolved
in water
Summary
(you can always write your own summary)
• Explain the Law of Conservation of Mass in your own words
and apply it to chemical reactions:
• What is the difference between the reactants and products
in a chemical reaction?
• Describe the process of balancing chemical reactions, be
sure to explain how you count atoms on both sides of the
equation
• What can you not change when balancing chemical
reactions?
• Is the reaction below balanced? Explain why or why not:
K + Cl2 KCl
Slide 5
UNIT: Chemical Reactions
TOPIC: Properties of Reactions
Objectives: Lesson 1 of 3
•
•
•
•
To learn how we recognize a chemical reaction has took place
To learn what a chemical reactions is
To learn how we balance chemical equations
To learn the symbols for each physical state in a chemical
reaction
Quickwrite
In 1-2 sentences answer one of the questions below:
• What sort of clues do think indicate that a chemical reaction is
happening in your car engine????
• What sort of clues indicate a chemical reaction when you drop a
piece of alka selzter in water????
• What are some by products produced when your body breaks
down sugar, C6H12O6????? What are some clues that this
reaction is occuring in your body????? Hint: think of
temperature!!!!
Evidence for a Chemical Reaction
• How do you know a chemical reaction has occurred?
• Chemists look for visual clues such a color or heat
change, a solid forms, bubbles are produced, a flame
occurs
• However, reactions are not always visible
• Sometimes the only signal that a reaction is occurring is
a change in temperature as heat is produced
What are some clues that a
chemical reaction has occurred?
•
•
•
•
•
A color change
A solid forms
Bubbles form
A heat change
A flame is produced
Chemical Reactions
• Chemists have learned that a chemical change always involves a
rearrangement of the ways in which atoms are grouped and combine
with one another
• For example, consider the reaction that occurs with your laboratory
bunsen burners
• In this reaction, methane (CH4) reacts with oxygen (O2) in the air
• As you know, a flame is produce and heat is released
• As the atoms rearrange themselves, two new chemicals are produced
carbon dioxide (CO2), and water (H2O)
CH4 + O2
CO2 + H2O
Chemical
Reactions
Such a change is called a chemical reaction
•
• Notice, the atoms were rearranged, Oxygen combined with Carbon and
Hydrogen to produce 2 new chemicals: Water & Carbon Dioxide
• Chemical reactions obey the Law of Conservation of Matter which states: Atoms
cannot be destroyed, they can only be rearranged
CH4 + O2
CO2
Methane (CH4)
Water(H
Carbon
Dioxide
2O) (CO2)
Oxygen(O2)
H2O
What is a Chemical Reaction?
• A chemical reaction is the change that occurs when
atoms rearrange themselves and form new
compounds
• Chemical reactions obey the first LAW of
conservation of MASS or MATTER which states:
Atoms and matter cannot be created or destroyed,
they can only be rearranged
Chemical Equations
• We represent chemical reactions by writing a
chemical equation in which the chemicals
present before the reaction are on the left of
the arrow, and the chemicals formed by the
reaction are on the right of the arrow
• The arrow indicates the direction of the
change CH4 + O2
CO2 + H2O
Chemical Equations
• In the reaction of methane with oxygen, we have:
CH4 + O2
CO2 + H2O
Reactants
Products
• The chemicals present on the left side of the
equation are known as the reactants
• The chemicals present on the right side of the
equation are known as the products
What is a Chemical Equation?
• An equation that uses the formulas of chemicals
compounds and elements to show the reactants and
products in a chemical change
• Chemicals present before the reaction are on the left of
the arrow (reactants), and the chemicals formed by the
reaction are on the right of the arrow (products)
Ex: CH4 + O2
CO2 + H2O
Balancing Chemical Reactions
• It is important to realize that in a chemical
reaction, atoms are neither created nor
destroyed
• In other words, their must be the same
number of each type of atom on the product
side as on the reactant side of the arrow
••
•
•
•
Balancing Chemical Reactions
In
other
words,
the
reaction
and
table
below
show
Oxygen
Remember,
atoms
beatoms
created
or
destroyed
in
chemical
reactions,
We
can
fix
this
by
putting
in
1atoms,
more
Oxygen
molecule
on1inthe
left
By
the
number
you
can
see
that
the
chemical
Notice,
there
are
2cannot
Oxygen
on
left
side
and
3that
Oxygen
atoms
on
We
group
molecules
by
putting
coefficients
front
ofatom
them:
Thecounting
reaction
below
is together
notof
balanced
is
created
and
2and
Hydrogen
atoms
are
destroyed
they
can only
be
rearranged!
(reactant)
side
1 more
Water
molecule
on
theleft
right
(product)
side
the
right
side;
4byHydrogen
the
side
and 2 apart:
equation
is
balanced
andare
shows
the
actual
numbers
molecules
We can
see
it isalso
notthere
balanced
taking
theonreactants
&ofproducts
Therefore,
the
reaction
cannot
way!
total in
number
of
atoms
musthappen
be
thethis
same
on both
sides
of the
arrow
The
table
now
has
equal
number
of atoms
on
both
sides
of the
equation
Hydrogen
on
the
right
side
involved
this
reaction
CH4
O+2 +2 O2
CO2
H+2+O +2H2O
H
H CH
H
O O
O C O
H OH
O O
Left
Reactant Side
C=
O=
1
2
4
H=
4
9
7
6
9
Total Number of Atoms
Right
H OH
Product Side
O=
1
34
H=
42
C=
Balancing Chemical Reactions
••••• We
In
other
can
fixwords,
this
by
putting
reaction
and
more
table
Water
molecule
show
that
on
the
1front
Oxygen
left(reactant)
atom
By
counting
the
number
of
you
can
see
the
chemical
Remember,
atoms
cannot
be1atoms,
created
orbelow
destroyed
in
chemical
reactions,
group
molecules
byon
putting
coefficients
in
ofon
them:
Notice,
there
is
1the
Oxygen
atoms
left
side
and
2that
Oxygen
atoms
The
reaction
below
istogether
notin
balanced
is
created
and
1only
Hydrogen
molecule
on
the
side and
they
cansee
rearranged!
equation
ismore
balanced
andthe
shows
actual
numbers
atoms
the
right
side;
therefore
chemical
equation
is NOT of
balanced
• side
We
can
it be
is
NOT
balanced
bythe
taking
theright(product)
reactants
& products
•• The
Therefore,
table
thehas
reaction
equal
cannot
number
of
onway!
both
sides
of the
equation
The
total now
number
of
atoms
musthappen
beatoms
the this
same
on both
sides
of the
arrow
molecules
involved
in
this
reaction
apart:
2 H2
H2O + 2 H2O
H OH
H OH
Left
Reactant Side
O=
1
2
42
H=
H H
3
6
6
4
H H
O O
Right
Product Side
O=
2
24
H=
Total Number of Atoms
H+2 + O2
Subscripts and Coefficients
• When balancing chemical equations, it is important to note
that the subscripts can never change
• For example, in the equation below, the subscript of 4 in
methane cannot be changed, neither can the subscripts 2 in
Oxygen, Carbon dioxide and Water
CH4 + 2 O2
CO2 + 2H2O
• Only coefficients can be added by putting whole numbers in
front of the compounds when balancing chemical reactions
How Do we Balance Chemical Equations?
• By placing coefficients in front of each molecule
or compound
• Subscripts cannot be changed!
• Ex: CH4 + 2O2 CO2 + 2H2O
Balancing Chemical Equations
Remember: When balancing chemical equations, it is important to
note that the subscripts can never change!!!!
2
___O
___O
3
2
3
___
2 Mg + ___ O2
___
2 MgO
Practice:
Determine how many atoms of each element are in
each compound below:
1)
2)
3)
4)
2 Na + ___ Cl
___
2
4 Fe + ___
3 O
___
2
___
4 Al + ___
3 O2
2 Na + ___ F
___
2
2
___
NaCl
2 Fe O
___
2 3
___
2 Al2O3
2 NaF
___
Physical States
• In a reaction, we often use symbols to represent the physical state of
the reactants and products
• Look at the reaction below when sodium metal reacts with water:
Na(s) + H2O(l)
H2(g) + NaOH(aq)
• The symbol (s) tells us that Sodium (Na) is in the solid
state
• The symbol (l) tells us the water (H2O) is in the liquid
state
• The symbol (g) tells us the hydrogen (H2) is in the
gaseous state
• Finally, the symbol (aq) tells us that sodium hydroxide
(NaOH) is aqueous or dissolved in water
Symbol
State
(s)
solid
(l)
(g)
(aq)
liquid
gas
aqueous
What do the symbols represent in a
chemical equation?
• The symbols represent the physical state of the
reactants and products
Symbol
State
solid
Na(s) + H2O(l)
H2(g) + NaOH(aq) (s)
(l)
(g)
(aq)
liquid
gas
aqueous
or dissolved
in water
Summary
(you can always write your own summary)
• Explain the Law of Conservation of Mass in your own words
and apply it to chemical reactions:
• What is the difference between the reactants and products
in a chemical reaction?
• Describe the process of balancing chemical reactions, be
sure to explain how you count atoms on both sides of the
equation
• What can you not change when balancing chemical
reactions?
• Is the reaction below balanced? Explain why or why not:
K + Cl2 KCl
Slide 6
UNIT: Chemical Reactions
TOPIC: Properties of Reactions
Objectives: Lesson 1 of 3
•
•
•
•
To learn how we recognize a chemical reaction has took place
To learn what a chemical reactions is
To learn how we balance chemical equations
To learn the symbols for each physical state in a chemical
reaction
Quickwrite
In 1-2 sentences answer one of the questions below:
• What sort of clues do think indicate that a chemical reaction is
happening in your car engine????
• What sort of clues indicate a chemical reaction when you drop a
piece of alka selzter in water????
• What are some by products produced when your body breaks
down sugar, C6H12O6????? What are some clues that this
reaction is occuring in your body????? Hint: think of
temperature!!!!
Evidence for a Chemical Reaction
• How do you know a chemical reaction has occurred?
• Chemists look for visual clues such a color or heat
change, a solid forms, bubbles are produced, a flame
occurs
• However, reactions are not always visible
• Sometimes the only signal that a reaction is occurring is
a change in temperature as heat is produced
What are some clues that a
chemical reaction has occurred?
•
•
•
•
•
A color change
A solid forms
Bubbles form
A heat change
A flame is produced
Chemical Reactions
• Chemists have learned that a chemical change always involves a
rearrangement of the ways in which atoms are grouped and combine
with one another
• For example, consider the reaction that occurs with your laboratory
bunsen burners
• In this reaction, methane (CH4) reacts with oxygen (O2) in the air
• As you know, a flame is produce and heat is released
• As the atoms rearrange themselves, two new chemicals are produced
carbon dioxide (CO2), and water (H2O)
CH4 + O2
CO2 + H2O
Chemical
Reactions
Such a change is called a chemical reaction
•
• Notice, the atoms were rearranged, Oxygen combined with Carbon and
Hydrogen to produce 2 new chemicals: Water & Carbon Dioxide
• Chemical reactions obey the Law of Conservation of Matter which states: Atoms
cannot be destroyed, they can only be rearranged
CH4 + O2
CO2
Methane (CH4)
Water(H
Carbon
Dioxide
2O) (CO2)
Oxygen(O2)
H2O
What is a Chemical Reaction?
• A chemical reaction is the change that occurs when
atoms rearrange themselves and form new
compounds
• Chemical reactions obey the first LAW of
conservation of MASS or MATTER which states:
Atoms and matter cannot be created or destroyed,
they can only be rearranged
Chemical Equations
• We represent chemical reactions by writing a
chemical equation in which the chemicals
present before the reaction are on the left of
the arrow, and the chemicals formed by the
reaction are on the right of the arrow
• The arrow indicates the direction of the
change CH4 + O2
CO2 + H2O
Chemical Equations
• In the reaction of methane with oxygen, we have:
CH4 + O2
CO2 + H2O
Reactants
Products
• The chemicals present on the left side of the
equation are known as the reactants
• The chemicals present on the right side of the
equation are known as the products
What is a Chemical Equation?
• An equation that uses the formulas of chemicals
compounds and elements to show the reactants and
products in a chemical change
• Chemicals present before the reaction are on the left of
the arrow (reactants), and the chemicals formed by the
reaction are on the right of the arrow (products)
Ex: CH4 + O2
CO2 + H2O
Balancing Chemical Reactions
• It is important to realize that in a chemical
reaction, atoms are neither created nor
destroyed
• In other words, their must be the same
number of each type of atom on the product
side as on the reactant side of the arrow
••
•
•
•
Balancing Chemical Reactions
In
other
words,
the
reaction
and
table
below
show
Oxygen
Remember,
atoms
beatoms
created
or
destroyed
in
chemical
reactions,
We
can
fix
this
by
putting
in
1atoms,
more
Oxygen
molecule
on1inthe
left
By
the
number
you
can
see
that
the
chemical
Notice,
there
are
2cannot
Oxygen
on
left
side
and
3that
Oxygen
atoms
on
We
group
molecules
by
putting
coefficients
front
ofatom
them:
Thecounting
reaction
below
is together
notof
balanced
is
created
and
2and
Hydrogen
atoms
are
destroyed
they
can only
be
rearranged!
(reactant)
side
1 more
Water
molecule
on
theleft
right
(product)
side
the
right
side;
4byHydrogen
the
side
and 2 apart:
equation
is
balanced
andare
shows
the
actual
numbers
molecules
We can
see
it isalso
notthere
balanced
taking
theonreactants
&ofproducts
Therefore,
the
reaction
cannot
way!
total in
number
of
atoms
musthappen
be
thethis
same
on both
sides
of the
arrow
The
table
now
has
equal
number
of atoms
on
both
sides
of the
equation
Hydrogen
on
the
right
side
involved
this
reaction
CH4
O+2 +2 O2
CO2
H+2+O +2H2O
H
H CH
H
O O
O C O
H OH
O O
Left
Reactant Side
C=
O=
1
2
4
H=
4
9
7
6
9
Total Number of Atoms
Right
H OH
Product Side
O=
1
34
H=
42
C=
Balancing Chemical Reactions
••••• We
In
other
can
fixwords,
this
by
putting
reaction
and
more
table
Water
molecule
show
that
on
the
1front
Oxygen
left(reactant)
atom
By
counting
the
number
of
you
can
see
the
chemical
Remember,
atoms
cannot
be1atoms,
created
orbelow
destroyed
in
chemical
reactions,
group
molecules
byon
putting
coefficients
in
ofon
them:
Notice,
there
is
1the
Oxygen
atoms
left
side
and
2that
Oxygen
atoms
The
reaction
below
istogether
notin
balanced
is
created
and
1only
Hydrogen
molecule
on
the
side and
they
cansee
rearranged!
equation
ismore
balanced
andthe
shows
actual
numbers
atoms
the
right
side;
therefore
chemical
equation
is NOT of
balanced
• side
We
can
it be
is
NOT
balanced
bythe
taking
theright(product)
reactants
& products
•• The
Therefore,
table
thehas
reaction
equal
cannot
number
of
onway!
both
sides
of the
equation
The
total now
number
of
atoms
musthappen
beatoms
the this
same
on both
sides
of the
arrow
molecules
involved
in
this
reaction
apart:
2 H2
H2O + 2 H2O
H OH
H OH
Left
Reactant Side
O=
1
2
42
H=
H H
3
6
6
4
H H
O O
Right
Product Side
O=
2
24
H=
Total Number of Atoms
H+2 + O2
Subscripts and Coefficients
• When balancing chemical equations, it is important to note
that the subscripts can never change
• For example, in the equation below, the subscript of 4 in
methane cannot be changed, neither can the subscripts 2 in
Oxygen, Carbon dioxide and Water
CH4 + 2 O2
CO2 + 2H2O
• Only coefficients can be added by putting whole numbers in
front of the compounds when balancing chemical reactions
How Do we Balance Chemical Equations?
• By placing coefficients in front of each molecule
or compound
• Subscripts cannot be changed!
• Ex: CH4 + 2O2 CO2 + 2H2O
Balancing Chemical Equations
Remember: When balancing chemical equations, it is important to
note that the subscripts can never change!!!!
2
___O
___O
3
2
3
___
2 Mg + ___ O2
___
2 MgO
Practice:
Determine how many atoms of each element are in
each compound below:
1)
2)
3)
4)
2 Na + ___ Cl
___
2
4 Fe + ___
3 O
___
2
___
4 Al + ___
3 O2
2 Na + ___ F
___
2
2
___
NaCl
2 Fe O
___
2 3
___
2 Al2O3
2 NaF
___
Physical States
• In a reaction, we often use symbols to represent the physical state of
the reactants and products
• Look at the reaction below when sodium metal reacts with water:
Na(s) + H2O(l)
H2(g) + NaOH(aq)
• The symbol (s) tells us that Sodium (Na) is in the solid
state
• The symbol (l) tells us the water (H2O) is in the liquid
state
• The symbol (g) tells us the hydrogen (H2) is in the
gaseous state
• Finally, the symbol (aq) tells us that sodium hydroxide
(NaOH) is aqueous or dissolved in water
Symbol
State
(s)
solid
(l)
(g)
(aq)
liquid
gas
aqueous
What do the symbols represent in a
chemical equation?
• The symbols represent the physical state of the
reactants and products
Symbol
State
solid
Na(s) + H2O(l)
H2(g) + NaOH(aq) (s)
(l)
(g)
(aq)
liquid
gas
aqueous
or dissolved
in water
Summary
(you can always write your own summary)
• Explain the Law of Conservation of Mass in your own words
and apply it to chemical reactions:
• What is the difference between the reactants and products
in a chemical reaction?
• Describe the process of balancing chemical reactions, be
sure to explain how you count atoms on both sides of the
equation
• What can you not change when balancing chemical
reactions?
• Is the reaction below balanced? Explain why or why not:
K + Cl2 KCl
Slide 7
UNIT: Chemical Reactions
TOPIC: Properties of Reactions
Objectives: Lesson 1 of 3
•
•
•
•
To learn how we recognize a chemical reaction has took place
To learn what a chemical reactions is
To learn how we balance chemical equations
To learn the symbols for each physical state in a chemical
reaction
Quickwrite
In 1-2 sentences answer one of the questions below:
• What sort of clues do think indicate that a chemical reaction is
happening in your car engine????
• What sort of clues indicate a chemical reaction when you drop a
piece of alka selzter in water????
• What are some by products produced when your body breaks
down sugar, C6H12O6????? What are some clues that this
reaction is occuring in your body????? Hint: think of
temperature!!!!
Evidence for a Chemical Reaction
• How do you know a chemical reaction has occurred?
• Chemists look for visual clues such a color or heat
change, a solid forms, bubbles are produced, a flame
occurs
• However, reactions are not always visible
• Sometimes the only signal that a reaction is occurring is
a change in temperature as heat is produced
What are some clues that a
chemical reaction has occurred?
•
•
•
•
•
A color change
A solid forms
Bubbles form
A heat change
A flame is produced
Chemical Reactions
• Chemists have learned that a chemical change always involves a
rearrangement of the ways in which atoms are grouped and combine
with one another
• For example, consider the reaction that occurs with your laboratory
bunsen burners
• In this reaction, methane (CH4) reacts with oxygen (O2) in the air
• As you know, a flame is produce and heat is released
• As the atoms rearrange themselves, two new chemicals are produced
carbon dioxide (CO2), and water (H2O)
CH4 + O2
CO2 + H2O
Chemical
Reactions
Such a change is called a chemical reaction
•
• Notice, the atoms were rearranged, Oxygen combined with Carbon and
Hydrogen to produce 2 new chemicals: Water & Carbon Dioxide
• Chemical reactions obey the Law of Conservation of Matter which states: Atoms
cannot be destroyed, they can only be rearranged
CH4 + O2
CO2
Methane (CH4)
Water(H
Carbon
Dioxide
2O) (CO2)
Oxygen(O2)
H2O
What is a Chemical Reaction?
• A chemical reaction is the change that occurs when
atoms rearrange themselves and form new
compounds
• Chemical reactions obey the first LAW of
conservation of MASS or MATTER which states:
Atoms and matter cannot be created or destroyed,
they can only be rearranged
Chemical Equations
• We represent chemical reactions by writing a
chemical equation in which the chemicals
present before the reaction are on the left of
the arrow, and the chemicals formed by the
reaction are on the right of the arrow
• The arrow indicates the direction of the
change CH4 + O2
CO2 + H2O
Chemical Equations
• In the reaction of methane with oxygen, we have:
CH4 + O2
CO2 + H2O
Reactants
Products
• The chemicals present on the left side of the
equation are known as the reactants
• The chemicals present on the right side of the
equation are known as the products
What is a Chemical Equation?
• An equation that uses the formulas of chemicals
compounds and elements to show the reactants and
products in a chemical change
• Chemicals present before the reaction are on the left of
the arrow (reactants), and the chemicals formed by the
reaction are on the right of the arrow (products)
Ex: CH4 + O2
CO2 + H2O
Balancing Chemical Reactions
• It is important to realize that in a chemical
reaction, atoms are neither created nor
destroyed
• In other words, their must be the same
number of each type of atom on the product
side as on the reactant side of the arrow
••
•
•
•
Balancing Chemical Reactions
In
other
words,
the
reaction
and
table
below
show
Oxygen
Remember,
atoms
beatoms
created
or
destroyed
in
chemical
reactions,
We
can
fix
this
by
putting
in
1atoms,
more
Oxygen
molecule
on1inthe
left
By
the
number
you
can
see
that
the
chemical
Notice,
there
are
2cannot
Oxygen
on
left
side
and
3that
Oxygen
atoms
on
We
group
molecules
by
putting
coefficients
front
ofatom
them:
Thecounting
reaction
below
is together
notof
balanced
is
created
and
2and
Hydrogen
atoms
are
destroyed
they
can only
be
rearranged!
(reactant)
side
1 more
Water
molecule
on
theleft
right
(product)
side
the
right
side;
4byHydrogen
the
side
and 2 apart:
equation
is
balanced
andare
shows
the
actual
numbers
molecules
We can
see
it isalso
notthere
balanced
taking
theonreactants
&ofproducts
Therefore,
the
reaction
cannot
way!
total in
number
of
atoms
musthappen
be
thethis
same
on both
sides
of the
arrow
The
table
now
has
equal
number
of atoms
on
both
sides
of the
equation
Hydrogen
on
the
right
side
involved
this
reaction
CH4
O+2 +2 O2
CO2
H+2+O +2H2O
H
H CH
H
O O
O C O
H OH
O O
Left
Reactant Side
C=
O=
1
2
4
H=
4
9
7
6
9
Total Number of Atoms
Right
H OH
Product Side
O=
1
34
H=
42
C=
Balancing Chemical Reactions
••••• We
In
other
can
fixwords,
this
by
putting
reaction
and
more
table
Water
molecule
show
that
on
the
1front
Oxygen
left(reactant)
atom
By
counting
the
number
of
you
can
see
the
chemical
Remember,
atoms
cannot
be1atoms,
created
orbelow
destroyed
in
chemical
reactions,
group
molecules
byon
putting
coefficients
in
ofon
them:
Notice,
there
is
1the
Oxygen
atoms
left
side
and
2that
Oxygen
atoms
The
reaction
below
istogether
notin
balanced
is
created
and
1only
Hydrogen
molecule
on
the
side and
they
cansee
rearranged!
equation
ismore
balanced
andthe
shows
actual
numbers
atoms
the
right
side;
therefore
chemical
equation
is NOT of
balanced
• side
We
can
it be
is
NOT
balanced
bythe
taking
theright(product)
reactants
& products
•• The
Therefore,
table
thehas
reaction
equal
cannot
number
of
onway!
both
sides
of the
equation
The
total now
number
of
atoms
musthappen
beatoms
the this
same
on both
sides
of the
arrow
molecules
involved
in
this
reaction
apart:
2 H2
H2O + 2 H2O
H OH
H OH
Left
Reactant Side
O=
1
2
42
H=
H H
3
6
6
4
H H
O O
Right
Product Side
O=
2
24
H=
Total Number of Atoms
H+2 + O2
Subscripts and Coefficients
• When balancing chemical equations, it is important to note
that the subscripts can never change
• For example, in the equation below, the subscript of 4 in
methane cannot be changed, neither can the subscripts 2 in
Oxygen, Carbon dioxide and Water
CH4 + 2 O2
CO2 + 2H2O
• Only coefficients can be added by putting whole numbers in
front of the compounds when balancing chemical reactions
How Do we Balance Chemical Equations?
• By placing coefficients in front of each molecule
or compound
• Subscripts cannot be changed!
• Ex: CH4 + 2O2 CO2 + 2H2O
Balancing Chemical Equations
Remember: When balancing chemical equations, it is important to
note that the subscripts can never change!!!!
2
___O
___O
3
2
3
___
2 Mg + ___ O2
___
2 MgO
Practice:
Determine how many atoms of each element are in
each compound below:
1)
2)
3)
4)
2 Na + ___ Cl
___
2
4 Fe + ___
3 O
___
2
___
4 Al + ___
3 O2
2 Na + ___ F
___
2
2
___
NaCl
2 Fe O
___
2 3
___
2 Al2O3
2 NaF
___
Physical States
• In a reaction, we often use symbols to represent the physical state of
the reactants and products
• Look at the reaction below when sodium metal reacts with water:
Na(s) + H2O(l)
H2(g) + NaOH(aq)
• The symbol (s) tells us that Sodium (Na) is in the solid
state
• The symbol (l) tells us the water (H2O) is in the liquid
state
• The symbol (g) tells us the hydrogen (H2) is in the
gaseous state
• Finally, the symbol (aq) tells us that sodium hydroxide
(NaOH) is aqueous or dissolved in water
Symbol
State
(s)
solid
(l)
(g)
(aq)
liquid
gas
aqueous
What do the symbols represent in a
chemical equation?
• The symbols represent the physical state of the
reactants and products
Symbol
State
solid
Na(s) + H2O(l)
H2(g) + NaOH(aq) (s)
(l)
(g)
(aq)
liquid
gas
aqueous
or dissolved
in water
Summary
(you can always write your own summary)
• Explain the Law of Conservation of Mass in your own words
and apply it to chemical reactions:
• What is the difference between the reactants and products
in a chemical reaction?
• Describe the process of balancing chemical reactions, be
sure to explain how you count atoms on both sides of the
equation
• What can you not change when balancing chemical
reactions?
• Is the reaction below balanced? Explain why or why not:
K + Cl2 KCl
Slide 8
UNIT: Chemical Reactions
TOPIC: Properties of Reactions
Objectives: Lesson 1 of 3
•
•
•
•
To learn how we recognize a chemical reaction has took place
To learn what a chemical reactions is
To learn how we balance chemical equations
To learn the symbols for each physical state in a chemical
reaction
Quickwrite
In 1-2 sentences answer one of the questions below:
• What sort of clues do think indicate that a chemical reaction is
happening in your car engine????
• What sort of clues indicate a chemical reaction when you drop a
piece of alka selzter in water????
• What are some by products produced when your body breaks
down sugar, C6H12O6????? What are some clues that this
reaction is occuring in your body????? Hint: think of
temperature!!!!
Evidence for a Chemical Reaction
• How do you know a chemical reaction has occurred?
• Chemists look for visual clues such a color or heat
change, a solid forms, bubbles are produced, a flame
occurs
• However, reactions are not always visible
• Sometimes the only signal that a reaction is occurring is
a change in temperature as heat is produced
What are some clues that a
chemical reaction has occurred?
•
•
•
•
•
A color change
A solid forms
Bubbles form
A heat change
A flame is produced
Chemical Reactions
• Chemists have learned that a chemical change always involves a
rearrangement of the ways in which atoms are grouped and combine
with one another
• For example, consider the reaction that occurs with your laboratory
bunsen burners
• In this reaction, methane (CH4) reacts with oxygen (O2) in the air
• As you know, a flame is produce and heat is released
• As the atoms rearrange themselves, two new chemicals are produced
carbon dioxide (CO2), and water (H2O)
CH4 + O2
CO2 + H2O
Chemical
Reactions
Such a change is called a chemical reaction
•
• Notice, the atoms were rearranged, Oxygen combined with Carbon and
Hydrogen to produce 2 new chemicals: Water & Carbon Dioxide
• Chemical reactions obey the Law of Conservation of Matter which states: Atoms
cannot be destroyed, they can only be rearranged
CH4 + O2
CO2
Methane (CH4)
Water(H
Carbon
Dioxide
2O) (CO2)
Oxygen(O2)
H2O
What is a Chemical Reaction?
• A chemical reaction is the change that occurs when
atoms rearrange themselves and form new
compounds
• Chemical reactions obey the first LAW of
conservation of MASS or MATTER which states:
Atoms and matter cannot be created or destroyed,
they can only be rearranged
Chemical Equations
• We represent chemical reactions by writing a
chemical equation in which the chemicals
present before the reaction are on the left of
the arrow, and the chemicals formed by the
reaction are on the right of the arrow
• The arrow indicates the direction of the
change CH4 + O2
CO2 + H2O
Chemical Equations
• In the reaction of methane with oxygen, we have:
CH4 + O2
CO2 + H2O
Reactants
Products
• The chemicals present on the left side of the
equation are known as the reactants
• The chemicals present on the right side of the
equation are known as the products
What is a Chemical Equation?
• An equation that uses the formulas of chemicals
compounds and elements to show the reactants and
products in a chemical change
• Chemicals present before the reaction are on the left of
the arrow (reactants), and the chemicals formed by the
reaction are on the right of the arrow (products)
Ex: CH4 + O2
CO2 + H2O
Balancing Chemical Reactions
• It is important to realize that in a chemical
reaction, atoms are neither created nor
destroyed
• In other words, their must be the same
number of each type of atom on the product
side as on the reactant side of the arrow
••
•
•
•
Balancing Chemical Reactions
In
other
words,
the
reaction
and
table
below
show
Oxygen
Remember,
atoms
beatoms
created
or
destroyed
in
chemical
reactions,
We
can
fix
this
by
putting
in
1atoms,
more
Oxygen
molecule
on1inthe
left
By
the
number
you
can
see
that
the
chemical
Notice,
there
are
2cannot
Oxygen
on
left
side
and
3that
Oxygen
atoms
on
We
group
molecules
by
putting
coefficients
front
ofatom
them:
Thecounting
reaction
below
is together
notof
balanced
is
created
and
2and
Hydrogen
atoms
are
destroyed
they
can only
be
rearranged!
(reactant)
side
1 more
Water
molecule
on
theleft
right
(product)
side
the
right
side;
4byHydrogen
the
side
and 2 apart:
equation
is
balanced
andare
shows
the
actual
numbers
molecules
We can
see
it isalso
notthere
balanced
taking
theonreactants
&ofproducts
Therefore,
the
reaction
cannot
way!
total in
number
of
atoms
musthappen
be
thethis
same
on both
sides
of the
arrow
The
table
now
has
equal
number
of atoms
on
both
sides
of the
equation
Hydrogen
on
the
right
side
involved
this
reaction
CH4
O+2 +2 O2
CO2
H+2+O +2H2O
H
H CH
H
O O
O C O
H OH
O O
Left
Reactant Side
C=
O=
1
2
4
H=
4
9
7
6
9
Total Number of Atoms
Right
H OH
Product Side
O=
1
34
H=
42
C=
Balancing Chemical Reactions
••••• We
In
other
can
fixwords,
this
by
putting
reaction
and
more
table
Water
molecule
show
that
on
the
1front
Oxygen
left(reactant)
atom
By
counting
the
number
of
you
can
see
the
chemical
Remember,
atoms
cannot
be1atoms,
created
orbelow
destroyed
in
chemical
reactions,
group
molecules
byon
putting
coefficients
in
ofon
them:
Notice,
there
is
1the
Oxygen
atoms
left
side
and
2that
Oxygen
atoms
The
reaction
below
istogether
notin
balanced
is
created
and
1only
Hydrogen
molecule
on
the
side and
they
cansee
rearranged!
equation
ismore
balanced
andthe
shows
actual
numbers
atoms
the
right
side;
therefore
chemical
equation
is NOT of
balanced
• side
We
can
it be
is
NOT
balanced
bythe
taking
theright(product)
reactants
& products
•• The
Therefore,
table
thehas
reaction
equal
cannot
number
of
onway!
both
sides
of the
equation
The
total now
number
of
atoms
musthappen
beatoms
the this
same
on both
sides
of the
arrow
molecules
involved
in
this
reaction
apart:
2 H2
H2O + 2 H2O
H OH
H OH
Left
Reactant Side
O=
1
2
42
H=
H H
3
6
6
4
H H
O O
Right
Product Side
O=
2
24
H=
Total Number of Atoms
H+2 + O2
Subscripts and Coefficients
• When balancing chemical equations, it is important to note
that the subscripts can never change
• For example, in the equation below, the subscript of 4 in
methane cannot be changed, neither can the subscripts 2 in
Oxygen, Carbon dioxide and Water
CH4 + 2 O2
CO2 + 2H2O
• Only coefficients can be added by putting whole numbers in
front of the compounds when balancing chemical reactions
How Do we Balance Chemical Equations?
• By placing coefficients in front of each molecule
or compound
• Subscripts cannot be changed!
• Ex: CH4 + 2O2 CO2 + 2H2O
Balancing Chemical Equations
Remember: When balancing chemical equations, it is important to
note that the subscripts can never change!!!!
2
___O
___O
3
2
3
___
2 Mg + ___ O2
___
2 MgO
Practice:
Determine how many atoms of each element are in
each compound below:
1)
2)
3)
4)
2 Na + ___ Cl
___
2
4 Fe + ___
3 O
___
2
___
4 Al + ___
3 O2
2 Na + ___ F
___
2
2
___
NaCl
2 Fe O
___
2 3
___
2 Al2O3
2 NaF
___
Physical States
• In a reaction, we often use symbols to represent the physical state of
the reactants and products
• Look at the reaction below when sodium metal reacts with water:
Na(s) + H2O(l)
H2(g) + NaOH(aq)
• The symbol (s) tells us that Sodium (Na) is in the solid
state
• The symbol (l) tells us the water (H2O) is in the liquid
state
• The symbol (g) tells us the hydrogen (H2) is in the
gaseous state
• Finally, the symbol (aq) tells us that sodium hydroxide
(NaOH) is aqueous or dissolved in water
Symbol
State
(s)
solid
(l)
(g)
(aq)
liquid
gas
aqueous
What do the symbols represent in a
chemical equation?
• The symbols represent the physical state of the
reactants and products
Symbol
State
solid
Na(s) + H2O(l)
H2(g) + NaOH(aq) (s)
(l)
(g)
(aq)
liquid
gas
aqueous
or dissolved
in water
Summary
(you can always write your own summary)
• Explain the Law of Conservation of Mass in your own words
and apply it to chemical reactions:
• What is the difference between the reactants and products
in a chemical reaction?
• Describe the process of balancing chemical reactions, be
sure to explain how you count atoms on both sides of the
equation
• What can you not change when balancing chemical
reactions?
• Is the reaction below balanced? Explain why or why not:
K + Cl2 KCl
Slide 9
UNIT: Chemical Reactions
TOPIC: Properties of Reactions
Objectives: Lesson 1 of 3
•
•
•
•
To learn how we recognize a chemical reaction has took place
To learn what a chemical reactions is
To learn how we balance chemical equations
To learn the symbols for each physical state in a chemical
reaction
Quickwrite
In 1-2 sentences answer one of the questions below:
• What sort of clues do think indicate that a chemical reaction is
happening in your car engine????
• What sort of clues indicate a chemical reaction when you drop a
piece of alka selzter in water????
• What are some by products produced when your body breaks
down sugar, C6H12O6????? What are some clues that this
reaction is occuring in your body????? Hint: think of
temperature!!!!
Evidence for a Chemical Reaction
• How do you know a chemical reaction has occurred?
• Chemists look for visual clues such a color or heat
change, a solid forms, bubbles are produced, a flame
occurs
• However, reactions are not always visible
• Sometimes the only signal that a reaction is occurring is
a change in temperature as heat is produced
What are some clues that a
chemical reaction has occurred?
•
•
•
•
•
A color change
A solid forms
Bubbles form
A heat change
A flame is produced
Chemical Reactions
• Chemists have learned that a chemical change always involves a
rearrangement of the ways in which atoms are grouped and combine
with one another
• For example, consider the reaction that occurs with your laboratory
bunsen burners
• In this reaction, methane (CH4) reacts with oxygen (O2) in the air
• As you know, a flame is produce and heat is released
• As the atoms rearrange themselves, two new chemicals are produced
carbon dioxide (CO2), and water (H2O)
CH4 + O2
CO2 + H2O
Chemical
Reactions
Such a change is called a chemical reaction
•
• Notice, the atoms were rearranged, Oxygen combined with Carbon and
Hydrogen to produce 2 new chemicals: Water & Carbon Dioxide
• Chemical reactions obey the Law of Conservation of Matter which states: Atoms
cannot be destroyed, they can only be rearranged
CH4 + O2
CO2
Methane (CH4)
Water(H
Carbon
Dioxide
2O) (CO2)
Oxygen(O2)
H2O
What is a Chemical Reaction?
• A chemical reaction is the change that occurs when
atoms rearrange themselves and form new
compounds
• Chemical reactions obey the first LAW of
conservation of MASS or MATTER which states:
Atoms and matter cannot be created or destroyed,
they can only be rearranged
Chemical Equations
• We represent chemical reactions by writing a
chemical equation in which the chemicals
present before the reaction are on the left of
the arrow, and the chemicals formed by the
reaction are on the right of the arrow
• The arrow indicates the direction of the
change CH4 + O2
CO2 + H2O
Chemical Equations
• In the reaction of methane with oxygen, we have:
CH4 + O2
CO2 + H2O
Reactants
Products
• The chemicals present on the left side of the
equation are known as the reactants
• The chemicals present on the right side of the
equation are known as the products
What is a Chemical Equation?
• An equation that uses the formulas of chemicals
compounds and elements to show the reactants and
products in a chemical change
• Chemicals present before the reaction are on the left of
the arrow (reactants), and the chemicals formed by the
reaction are on the right of the arrow (products)
Ex: CH4 + O2
CO2 + H2O
Balancing Chemical Reactions
• It is important to realize that in a chemical
reaction, atoms are neither created nor
destroyed
• In other words, their must be the same
number of each type of atom on the product
side as on the reactant side of the arrow
••
•
•
•
Balancing Chemical Reactions
In
other
words,
the
reaction
and
table
below
show
Oxygen
Remember,
atoms
beatoms
created
or
destroyed
in
chemical
reactions,
We
can
fix
this
by
putting
in
1atoms,
more
Oxygen
molecule
on1inthe
left
By
the
number
you
can
see
that
the
chemical
Notice,
there
are
2cannot
Oxygen
on
left
side
and
3that
Oxygen
atoms
on
We
group
molecules
by
putting
coefficients
front
ofatom
them:
Thecounting
reaction
below
is together
notof
balanced
is
created
and
2and
Hydrogen
atoms
are
destroyed
they
can only
be
rearranged!
(reactant)
side
1 more
Water
molecule
on
theleft
right
(product)
side
the
right
side;
4byHydrogen
the
side
and 2 apart:
equation
is
balanced
andare
shows
the
actual
numbers
molecules
We can
see
it isalso
notthere
balanced
taking
theonreactants
&ofproducts
Therefore,
the
reaction
cannot
way!
total in
number
of
atoms
musthappen
be
thethis
same
on both
sides
of the
arrow
The
table
now
has
equal
number
of atoms
on
both
sides
of the
equation
Hydrogen
on
the
right
side
involved
this
reaction
CH4
O+2 +2 O2
CO2
H+2+O +2H2O
H
H CH
H
O O
O C O
H OH
O O
Left
Reactant Side
C=
O=
1
2
4
H=
4
9
7
6
9
Total Number of Atoms
Right
H OH
Product Side
O=
1
34
H=
42
C=
Balancing Chemical Reactions
••••• We
In
other
can
fixwords,
this
by
putting
reaction
and
more
table
Water
molecule
show
that
on
the
1front
Oxygen
left(reactant)
atom
By
counting
the
number
of
you
can
see
the
chemical
Remember,
atoms
cannot
be1atoms,
created
orbelow
destroyed
in
chemical
reactions,
group
molecules
byon
putting
coefficients
in
ofon
them:
Notice,
there
is
1the
Oxygen
atoms
left
side
and
2that
Oxygen
atoms
The
reaction
below
istogether
notin
balanced
is
created
and
1only
Hydrogen
molecule
on
the
side and
they
cansee
rearranged!
equation
ismore
balanced
andthe
shows
actual
numbers
atoms
the
right
side;
therefore
chemical
equation
is NOT of
balanced
• side
We
can
it be
is
NOT
balanced
bythe
taking
theright(product)
reactants
& products
•• The
Therefore,
table
thehas
reaction
equal
cannot
number
of
onway!
both
sides
of the
equation
The
total now
number
of
atoms
musthappen
beatoms
the this
same
on both
sides
of the
arrow
molecules
involved
in
this
reaction
apart:
2 H2
H2O + 2 H2O
H OH
H OH
Left
Reactant Side
O=
1
2
42
H=
H H
3
6
6
4
H H
O O
Right
Product Side
O=
2
24
H=
Total Number of Atoms
H+2 + O2
Subscripts and Coefficients
• When balancing chemical equations, it is important to note
that the subscripts can never change
• For example, in the equation below, the subscript of 4 in
methane cannot be changed, neither can the subscripts 2 in
Oxygen, Carbon dioxide and Water
CH4 + 2 O2
CO2 + 2H2O
• Only coefficients can be added by putting whole numbers in
front of the compounds when balancing chemical reactions
How Do we Balance Chemical Equations?
• By placing coefficients in front of each molecule
or compound
• Subscripts cannot be changed!
• Ex: CH4 + 2O2 CO2 + 2H2O
Balancing Chemical Equations
Remember: When balancing chemical equations, it is important to
note that the subscripts can never change!!!!
2
___O
___O
3
2
3
___
2 Mg + ___ O2
___
2 MgO
Practice:
Determine how many atoms of each element are in
each compound below:
1)
2)
3)
4)
2 Na + ___ Cl
___
2
4 Fe + ___
3 O
___
2
___
4 Al + ___
3 O2
2 Na + ___ F
___
2
2
___
NaCl
2 Fe O
___
2 3
___
2 Al2O3
2 NaF
___
Physical States
• In a reaction, we often use symbols to represent the physical state of
the reactants and products
• Look at the reaction below when sodium metal reacts with water:
Na(s) + H2O(l)
H2(g) + NaOH(aq)
• The symbol (s) tells us that Sodium (Na) is in the solid
state
• The symbol (l) tells us the water (H2O) is in the liquid
state
• The symbol (g) tells us the hydrogen (H2) is in the
gaseous state
• Finally, the symbol (aq) tells us that sodium hydroxide
(NaOH) is aqueous or dissolved in water
Symbol
State
(s)
solid
(l)
(g)
(aq)
liquid
gas
aqueous
What do the symbols represent in a
chemical equation?
• The symbols represent the physical state of the
reactants and products
Symbol
State
solid
Na(s) + H2O(l)
H2(g) + NaOH(aq) (s)
(l)
(g)
(aq)
liquid
gas
aqueous
or dissolved
in water
Summary
(you can always write your own summary)
• Explain the Law of Conservation of Mass in your own words
and apply it to chemical reactions:
• What is the difference between the reactants and products
in a chemical reaction?
• Describe the process of balancing chemical reactions, be
sure to explain how you count atoms on both sides of the
equation
• What can you not change when balancing chemical
reactions?
• Is the reaction below balanced? Explain why or why not:
K + Cl2 KCl
Slide 10
UNIT: Chemical Reactions
TOPIC: Properties of Reactions
Objectives: Lesson 1 of 3
•
•
•
•
To learn how we recognize a chemical reaction has took place
To learn what a chemical reactions is
To learn how we balance chemical equations
To learn the symbols for each physical state in a chemical
reaction
Quickwrite
In 1-2 sentences answer one of the questions below:
• What sort of clues do think indicate that a chemical reaction is
happening in your car engine????
• What sort of clues indicate a chemical reaction when you drop a
piece of alka selzter in water????
• What are some by products produced when your body breaks
down sugar, C6H12O6????? What are some clues that this
reaction is occuring in your body????? Hint: think of
temperature!!!!
Evidence for a Chemical Reaction
• How do you know a chemical reaction has occurred?
• Chemists look for visual clues such a color or heat
change, a solid forms, bubbles are produced, a flame
occurs
• However, reactions are not always visible
• Sometimes the only signal that a reaction is occurring is
a change in temperature as heat is produced
What are some clues that a
chemical reaction has occurred?
•
•
•
•
•
A color change
A solid forms
Bubbles form
A heat change
A flame is produced
Chemical Reactions
• Chemists have learned that a chemical change always involves a
rearrangement of the ways in which atoms are grouped and combine
with one another
• For example, consider the reaction that occurs with your laboratory
bunsen burners
• In this reaction, methane (CH4) reacts with oxygen (O2) in the air
• As you know, a flame is produce and heat is released
• As the atoms rearrange themselves, two new chemicals are produced
carbon dioxide (CO2), and water (H2O)
CH4 + O2
CO2 + H2O
Chemical
Reactions
Such a change is called a chemical reaction
•
• Notice, the atoms were rearranged, Oxygen combined with Carbon and
Hydrogen to produce 2 new chemicals: Water & Carbon Dioxide
• Chemical reactions obey the Law of Conservation of Matter which states: Atoms
cannot be destroyed, they can only be rearranged
CH4 + O2
CO2
Methane (CH4)
Water(H
Carbon
Dioxide
2O) (CO2)
Oxygen(O2)
H2O
What is a Chemical Reaction?
• A chemical reaction is the change that occurs when
atoms rearrange themselves and form new
compounds
• Chemical reactions obey the first LAW of
conservation of MASS or MATTER which states:
Atoms and matter cannot be created or destroyed,
they can only be rearranged
Chemical Equations
• We represent chemical reactions by writing a
chemical equation in which the chemicals
present before the reaction are on the left of
the arrow, and the chemicals formed by the
reaction are on the right of the arrow
• The arrow indicates the direction of the
change CH4 + O2
CO2 + H2O
Chemical Equations
• In the reaction of methane with oxygen, we have:
CH4 + O2
CO2 + H2O
Reactants
Products
• The chemicals present on the left side of the
equation are known as the reactants
• The chemicals present on the right side of the
equation are known as the products
What is a Chemical Equation?
• An equation that uses the formulas of chemicals
compounds and elements to show the reactants and
products in a chemical change
• Chemicals present before the reaction are on the left of
the arrow (reactants), and the chemicals formed by the
reaction are on the right of the arrow (products)
Ex: CH4 + O2
CO2 + H2O
Balancing Chemical Reactions
• It is important to realize that in a chemical
reaction, atoms are neither created nor
destroyed
• In other words, their must be the same
number of each type of atom on the product
side as on the reactant side of the arrow
••
•
•
•
Balancing Chemical Reactions
In
other
words,
the
reaction
and
table
below
show
Oxygen
Remember,
atoms
beatoms
created
or
destroyed
in
chemical
reactions,
We
can
fix
this
by
putting
in
1atoms,
more
Oxygen
molecule
on1inthe
left
By
the
number
you
can
see
that
the
chemical
Notice,
there
are
2cannot
Oxygen
on
left
side
and
3that
Oxygen
atoms
on
We
group
molecules
by
putting
coefficients
front
ofatom
them:
Thecounting
reaction
below
is together
notof
balanced
is
created
and
2and
Hydrogen
atoms
are
destroyed
they
can only
be
rearranged!
(reactant)
side
1 more
Water
molecule
on
theleft
right
(product)
side
the
right
side;
4byHydrogen
the
side
and 2 apart:
equation
is
balanced
andare
shows
the
actual
numbers
molecules
We can
see
it isalso
notthere
balanced
taking
theonreactants
&ofproducts
Therefore,
the
reaction
cannot
way!
total in
number
of
atoms
musthappen
be
thethis
same
on both
sides
of the
arrow
The
table
now
has
equal
number
of atoms
on
both
sides
of the
equation
Hydrogen
on
the
right
side
involved
this
reaction
CH4
O+2 +2 O2
CO2
H+2+O +2H2O
H
H CH
H
O O
O C O
H OH
O O
Left
Reactant Side
C=
O=
1
2
4
H=
4
9
7
6
9
Total Number of Atoms
Right
H OH
Product Side
O=
1
34
H=
42
C=
Balancing Chemical Reactions
••••• We
In
other
can
fixwords,
this
by
putting
reaction
and
more
table
Water
molecule
show
that
on
the
1front
Oxygen
left(reactant)
atom
By
counting
the
number
of
you
can
see
the
chemical
Remember,
atoms
cannot
be1atoms,
created
orbelow
destroyed
in
chemical
reactions,
group
molecules
byon
putting
coefficients
in
ofon
them:
Notice,
there
is
1the
Oxygen
atoms
left
side
and
2that
Oxygen
atoms
The
reaction
below
istogether
notin
balanced
is
created
and
1only
Hydrogen
molecule
on
the
side and
they
cansee
rearranged!
equation
ismore
balanced
andthe
shows
actual
numbers
atoms
the
right
side;
therefore
chemical
equation
is NOT of
balanced
• side
We
can
it be
is
NOT
balanced
bythe
taking
theright(product)
reactants
& products
•• The
Therefore,
table
thehas
reaction
equal
cannot
number
of
onway!
both
sides
of the
equation
The
total now
number
of
atoms
musthappen
beatoms
the this
same
on both
sides
of the
arrow
molecules
involved
in
this
reaction
apart:
2 H2
H2O + 2 H2O
H OH
H OH
Left
Reactant Side
O=
1
2
42
H=
H H
3
6
6
4
H H
O O
Right
Product Side
O=
2
24
H=
Total Number of Atoms
H+2 + O2
Subscripts and Coefficients
• When balancing chemical equations, it is important to note
that the subscripts can never change
• For example, in the equation below, the subscript of 4 in
methane cannot be changed, neither can the subscripts 2 in
Oxygen, Carbon dioxide and Water
CH4 + 2 O2
CO2 + 2H2O
• Only coefficients can be added by putting whole numbers in
front of the compounds when balancing chemical reactions
How Do we Balance Chemical Equations?
• By placing coefficients in front of each molecule
or compound
• Subscripts cannot be changed!
• Ex: CH4 + 2O2 CO2 + 2H2O
Balancing Chemical Equations
Remember: When balancing chemical equations, it is important to
note that the subscripts can never change!!!!
2
___O
___O
3
2
3
___
2 Mg + ___ O2
___
2 MgO
Practice:
Determine how many atoms of each element are in
each compound below:
1)
2)
3)
4)
2 Na + ___ Cl
___
2
4 Fe + ___
3 O
___
2
___
4 Al + ___
3 O2
2 Na + ___ F
___
2
2
___
NaCl
2 Fe O
___
2 3
___
2 Al2O3
2 NaF
___
Physical States
• In a reaction, we often use symbols to represent the physical state of
the reactants and products
• Look at the reaction below when sodium metal reacts with water:
Na(s) + H2O(l)
H2(g) + NaOH(aq)
• The symbol (s) tells us that Sodium (Na) is in the solid
state
• The symbol (l) tells us the water (H2O) is in the liquid
state
• The symbol (g) tells us the hydrogen (H2) is in the
gaseous state
• Finally, the symbol (aq) tells us that sodium hydroxide
(NaOH) is aqueous or dissolved in water
Symbol
State
(s)
solid
(l)
(g)
(aq)
liquid
gas
aqueous
What do the symbols represent in a
chemical equation?
• The symbols represent the physical state of the
reactants and products
Symbol
State
solid
Na(s) + H2O(l)
H2(g) + NaOH(aq) (s)
(l)
(g)
(aq)
liquid
gas
aqueous
or dissolved
in water
Summary
(you can always write your own summary)
• Explain the Law of Conservation of Mass in your own words
and apply it to chemical reactions:
• What is the difference between the reactants and products
in a chemical reaction?
• Describe the process of balancing chemical reactions, be
sure to explain how you count atoms on both sides of the
equation
• What can you not change when balancing chemical
reactions?
• Is the reaction below balanced? Explain why or why not:
K + Cl2 KCl
Slide 11
UNIT: Chemical Reactions
TOPIC: Properties of Reactions
Objectives: Lesson 1 of 3
•
•
•
•
To learn how we recognize a chemical reaction has took place
To learn what a chemical reactions is
To learn how we balance chemical equations
To learn the symbols for each physical state in a chemical
reaction
Quickwrite
In 1-2 sentences answer one of the questions below:
• What sort of clues do think indicate that a chemical reaction is
happening in your car engine????
• What sort of clues indicate a chemical reaction when you drop a
piece of alka selzter in water????
• What are some by products produced when your body breaks
down sugar, C6H12O6????? What are some clues that this
reaction is occuring in your body????? Hint: think of
temperature!!!!
Evidence for a Chemical Reaction
• How do you know a chemical reaction has occurred?
• Chemists look for visual clues such a color or heat
change, a solid forms, bubbles are produced, a flame
occurs
• However, reactions are not always visible
• Sometimes the only signal that a reaction is occurring is
a change in temperature as heat is produced
What are some clues that a
chemical reaction has occurred?
•
•
•
•
•
A color change
A solid forms
Bubbles form
A heat change
A flame is produced
Chemical Reactions
• Chemists have learned that a chemical change always involves a
rearrangement of the ways in which atoms are grouped and combine
with one another
• For example, consider the reaction that occurs with your laboratory
bunsen burners
• In this reaction, methane (CH4) reacts with oxygen (O2) in the air
• As you know, a flame is produce and heat is released
• As the atoms rearrange themselves, two new chemicals are produced
carbon dioxide (CO2), and water (H2O)
CH4 + O2
CO2 + H2O
Chemical
Reactions
Such a change is called a chemical reaction
•
• Notice, the atoms were rearranged, Oxygen combined with Carbon and
Hydrogen to produce 2 new chemicals: Water & Carbon Dioxide
• Chemical reactions obey the Law of Conservation of Matter which states: Atoms
cannot be destroyed, they can only be rearranged
CH4 + O2
CO2
Methane (CH4)
Water(H
Carbon
Dioxide
2O) (CO2)
Oxygen(O2)
H2O
What is a Chemical Reaction?
• A chemical reaction is the change that occurs when
atoms rearrange themselves and form new
compounds
• Chemical reactions obey the first LAW of
conservation of MASS or MATTER which states:
Atoms and matter cannot be created or destroyed,
they can only be rearranged
Chemical Equations
• We represent chemical reactions by writing a
chemical equation in which the chemicals
present before the reaction are on the left of
the arrow, and the chemicals formed by the
reaction are on the right of the arrow
• The arrow indicates the direction of the
change CH4 + O2
CO2 + H2O
Chemical Equations
• In the reaction of methane with oxygen, we have:
CH4 + O2
CO2 + H2O
Reactants
Products
• The chemicals present on the left side of the
equation are known as the reactants
• The chemicals present on the right side of the
equation are known as the products
What is a Chemical Equation?
• An equation that uses the formulas of chemicals
compounds and elements to show the reactants and
products in a chemical change
• Chemicals present before the reaction are on the left of
the arrow (reactants), and the chemicals formed by the
reaction are on the right of the arrow (products)
Ex: CH4 + O2
CO2 + H2O
Balancing Chemical Reactions
• It is important to realize that in a chemical
reaction, atoms are neither created nor
destroyed
• In other words, their must be the same
number of each type of atom on the product
side as on the reactant side of the arrow
••
•
•
•
Balancing Chemical Reactions
In
other
words,
the
reaction
and
table
below
show
Oxygen
Remember,
atoms
beatoms
created
or
destroyed
in
chemical
reactions,
We
can
fix
this
by
putting
in
1atoms,
more
Oxygen
molecule
on1inthe
left
By
the
number
you
can
see
that
the
chemical
Notice,
there
are
2cannot
Oxygen
on
left
side
and
3that
Oxygen
atoms
on
We
group
molecules
by
putting
coefficients
front
ofatom
them:
Thecounting
reaction
below
is together
notof
balanced
is
created
and
2and
Hydrogen
atoms
are
destroyed
they
can only
be
rearranged!
(reactant)
side
1 more
Water
molecule
on
theleft
right
(product)
side
the
right
side;
4byHydrogen
the
side
and 2 apart:
equation
is
balanced
andare
shows
the
actual
numbers
molecules
We can
see
it isalso
notthere
balanced
taking
theonreactants
&ofproducts
Therefore,
the
reaction
cannot
way!
total in
number
of
atoms
musthappen
be
thethis
same
on both
sides
of the
arrow
The
table
now
has
equal
number
of atoms
on
both
sides
of the
equation
Hydrogen
on
the
right
side
involved
this
reaction
CH4
O+2 +2 O2
CO2
H+2+O +2H2O
H
H CH
H
O O
O C O
H OH
O O
Left
Reactant Side
C=
O=
1
2
4
H=
4
9
7
6
9
Total Number of Atoms
Right
H OH
Product Side
O=
1
34
H=
42
C=
Balancing Chemical Reactions
••••• We
In
other
can
fixwords,
this
by
putting
reaction
and
more
table
Water
molecule
show
that
on
the
1front
Oxygen
left(reactant)
atom
By
counting
the
number
of
you
can
see
the
chemical
Remember,
atoms
cannot
be1atoms,
created
orbelow
destroyed
in
chemical
reactions,
group
molecules
byon
putting
coefficients
in
ofon
them:
Notice,
there
is
1the
Oxygen
atoms
left
side
and
2that
Oxygen
atoms
The
reaction
below
istogether
notin
balanced
is
created
and
1only
Hydrogen
molecule
on
the
side and
they
cansee
rearranged!
equation
ismore
balanced
andthe
shows
actual
numbers
atoms
the
right
side;
therefore
chemical
equation
is NOT of
balanced
• side
We
can
it be
is
NOT
balanced
bythe
taking
theright(product)
reactants
& products
•• The
Therefore,
table
thehas
reaction
equal
cannot
number
of
onway!
both
sides
of the
equation
The
total now
number
of
atoms
musthappen
beatoms
the this
same
on both
sides
of the
arrow
molecules
involved
in
this
reaction
apart:
2 H2
H2O + 2 H2O
H OH
H OH
Left
Reactant Side
O=
1
2
42
H=
H H
3
6
6
4
H H
O O
Right
Product Side
O=
2
24
H=
Total Number of Atoms
H+2 + O2
Subscripts and Coefficients
• When balancing chemical equations, it is important to note
that the subscripts can never change
• For example, in the equation below, the subscript of 4 in
methane cannot be changed, neither can the subscripts 2 in
Oxygen, Carbon dioxide and Water
CH4 + 2 O2
CO2 + 2H2O
• Only coefficients can be added by putting whole numbers in
front of the compounds when balancing chemical reactions
How Do we Balance Chemical Equations?
• By placing coefficients in front of each molecule
or compound
• Subscripts cannot be changed!
• Ex: CH4 + 2O2 CO2 + 2H2O
Balancing Chemical Equations
Remember: When balancing chemical equations, it is important to
note that the subscripts can never change!!!!
2
___O
___O
3
2
3
___
2 Mg + ___ O2
___
2 MgO
Practice:
Determine how many atoms of each element are in
each compound below:
1)
2)
3)
4)
2 Na + ___ Cl
___
2
4 Fe + ___
3 O
___
2
___
4 Al + ___
3 O2
2 Na + ___ F
___
2
2
___
NaCl
2 Fe O
___
2 3
___
2 Al2O3
2 NaF
___
Physical States
• In a reaction, we often use symbols to represent the physical state of
the reactants and products
• Look at the reaction below when sodium metal reacts with water:
Na(s) + H2O(l)
H2(g) + NaOH(aq)
• The symbol (s) tells us that Sodium (Na) is in the solid
state
• The symbol (l) tells us the water (H2O) is in the liquid
state
• The symbol (g) tells us the hydrogen (H2) is in the
gaseous state
• Finally, the symbol (aq) tells us that sodium hydroxide
(NaOH) is aqueous or dissolved in water
Symbol
State
(s)
solid
(l)
(g)
(aq)
liquid
gas
aqueous
What do the symbols represent in a
chemical equation?
• The symbols represent the physical state of the
reactants and products
Symbol
State
solid
Na(s) + H2O(l)
H2(g) + NaOH(aq) (s)
(l)
(g)
(aq)
liquid
gas
aqueous
or dissolved
in water
Summary
(you can always write your own summary)
• Explain the Law of Conservation of Mass in your own words
and apply it to chemical reactions:
• What is the difference between the reactants and products
in a chemical reaction?
• Describe the process of balancing chemical reactions, be
sure to explain how you count atoms on both sides of the
equation
• What can you not change when balancing chemical
reactions?
• Is the reaction below balanced? Explain why or why not:
K + Cl2 KCl
Slide 12
UNIT: Chemical Reactions
TOPIC: Properties of Reactions
Objectives: Lesson 1 of 3
•
•
•
•
To learn how we recognize a chemical reaction has took place
To learn what a chemical reactions is
To learn how we balance chemical equations
To learn the symbols for each physical state in a chemical
reaction
Quickwrite
In 1-2 sentences answer one of the questions below:
• What sort of clues do think indicate that a chemical reaction is
happening in your car engine????
• What sort of clues indicate a chemical reaction when you drop a
piece of alka selzter in water????
• What are some by products produced when your body breaks
down sugar, C6H12O6????? What are some clues that this
reaction is occuring in your body????? Hint: think of
temperature!!!!
Evidence for a Chemical Reaction
• How do you know a chemical reaction has occurred?
• Chemists look for visual clues such a color or heat
change, a solid forms, bubbles are produced, a flame
occurs
• However, reactions are not always visible
• Sometimes the only signal that a reaction is occurring is
a change in temperature as heat is produced
What are some clues that a
chemical reaction has occurred?
•
•
•
•
•
A color change
A solid forms
Bubbles form
A heat change
A flame is produced
Chemical Reactions
• Chemists have learned that a chemical change always involves a
rearrangement of the ways in which atoms are grouped and combine
with one another
• For example, consider the reaction that occurs with your laboratory
bunsen burners
• In this reaction, methane (CH4) reacts with oxygen (O2) in the air
• As you know, a flame is produce and heat is released
• As the atoms rearrange themselves, two new chemicals are produced
carbon dioxide (CO2), and water (H2O)
CH4 + O2
CO2 + H2O
Chemical
Reactions
Such a change is called a chemical reaction
•
• Notice, the atoms were rearranged, Oxygen combined with Carbon and
Hydrogen to produce 2 new chemicals: Water & Carbon Dioxide
• Chemical reactions obey the Law of Conservation of Matter which states: Atoms
cannot be destroyed, they can only be rearranged
CH4 + O2
CO2
Methane (CH4)
Water(H
Carbon
Dioxide
2O) (CO2)
Oxygen(O2)
H2O
What is a Chemical Reaction?
• A chemical reaction is the change that occurs when
atoms rearrange themselves and form new
compounds
• Chemical reactions obey the first LAW of
conservation of MASS or MATTER which states:
Atoms and matter cannot be created or destroyed,
they can only be rearranged
Chemical Equations
• We represent chemical reactions by writing a
chemical equation in which the chemicals
present before the reaction are on the left of
the arrow, and the chemicals formed by the
reaction are on the right of the arrow
• The arrow indicates the direction of the
change CH4 + O2
CO2 + H2O
Chemical Equations
• In the reaction of methane with oxygen, we have:
CH4 + O2
CO2 + H2O
Reactants
Products
• The chemicals present on the left side of the
equation are known as the reactants
• The chemicals present on the right side of the
equation are known as the products
What is a Chemical Equation?
• An equation that uses the formulas of chemicals
compounds and elements to show the reactants and
products in a chemical change
• Chemicals present before the reaction are on the left of
the arrow (reactants), and the chemicals formed by the
reaction are on the right of the arrow (products)
Ex: CH4 + O2
CO2 + H2O
Balancing Chemical Reactions
• It is important to realize that in a chemical
reaction, atoms are neither created nor
destroyed
• In other words, their must be the same
number of each type of atom on the product
side as on the reactant side of the arrow
••
•
•
•
Balancing Chemical Reactions
In
other
words,
the
reaction
and
table
below
show
Oxygen
Remember,
atoms
beatoms
created
or
destroyed
in
chemical
reactions,
We
can
fix
this
by
putting
in
1atoms,
more
Oxygen
molecule
on1inthe
left
By
the
number
you
can
see
that
the
chemical
Notice,
there
are
2cannot
Oxygen
on
left
side
and
3that
Oxygen
atoms
on
We
group
molecules
by
putting
coefficients
front
ofatom
them:
Thecounting
reaction
below
is together
notof
balanced
is
created
and
2and
Hydrogen
atoms
are
destroyed
they
can only
be
rearranged!
(reactant)
side
1 more
Water
molecule
on
theleft
right
(product)
side
the
right
side;
4byHydrogen
the
side
and 2 apart:
equation
is
balanced
andare
shows
the
actual
numbers
molecules
We can
see
it isalso
notthere
balanced
taking
theonreactants
&ofproducts
Therefore,
the
reaction
cannot
way!
total in
number
of
atoms
musthappen
be
thethis
same
on both
sides
of the
arrow
The
table
now
has
equal
number
of atoms
on
both
sides
of the
equation
Hydrogen
on
the
right
side
involved
this
reaction
CH4
O+2 +2 O2
CO2
H+2+O +2H2O
H
H CH
H
O O
O C O
H OH
O O
Left
Reactant Side
C=
O=
1
2
4
H=
4
9
7
6
9
Total Number of Atoms
Right
H OH
Product Side
O=
1
34
H=
42
C=
Balancing Chemical Reactions
••••• We
In
other
can
fixwords,
this
by
putting
reaction
and
more
table
Water
molecule
show
that
on
the
1front
Oxygen
left(reactant)
atom
By
counting
the
number
of
you
can
see
the
chemical
Remember,
atoms
cannot
be1atoms,
created
orbelow
destroyed
in
chemical
reactions,
group
molecules
byon
putting
coefficients
in
ofon
them:
Notice,
there
is
1the
Oxygen
atoms
left
side
and
2that
Oxygen
atoms
The
reaction
below
istogether
notin
balanced
is
created
and
1only
Hydrogen
molecule
on
the
side and
they
cansee
rearranged!
equation
ismore
balanced
andthe
shows
actual
numbers
atoms
the
right
side;
therefore
chemical
equation
is NOT of
balanced
• side
We
can
it be
is
NOT
balanced
bythe
taking
theright(product)
reactants
& products
•• The
Therefore,
table
thehas
reaction
equal
cannot
number
of
onway!
both
sides
of the
equation
The
total now
number
of
atoms
musthappen
beatoms
the this
same
on both
sides
of the
arrow
molecules
involved
in
this
reaction
apart:
2 H2
H2O + 2 H2O
H OH
H OH
Left
Reactant Side
O=
1
2
42
H=
H H
3
6
6
4
H H
O O
Right
Product Side
O=
2
24
H=
Total Number of Atoms
H+2 + O2
Subscripts and Coefficients
• When balancing chemical equations, it is important to note
that the subscripts can never change
• For example, in the equation below, the subscript of 4 in
methane cannot be changed, neither can the subscripts 2 in
Oxygen, Carbon dioxide and Water
CH4 + 2 O2
CO2 + 2H2O
• Only coefficients can be added by putting whole numbers in
front of the compounds when balancing chemical reactions
How Do we Balance Chemical Equations?
• By placing coefficients in front of each molecule
or compound
• Subscripts cannot be changed!
• Ex: CH4 + 2O2 CO2 + 2H2O
Balancing Chemical Equations
Remember: When balancing chemical equations, it is important to
note that the subscripts can never change!!!!
2
___O
___O
3
2
3
___
2 Mg + ___ O2
___
2 MgO
Practice:
Determine how many atoms of each element are in
each compound below:
1)
2)
3)
4)
2 Na + ___ Cl
___
2
4 Fe + ___
3 O
___
2
___
4 Al + ___
3 O2
2 Na + ___ F
___
2
2
___
NaCl
2 Fe O
___
2 3
___
2 Al2O3
2 NaF
___
Physical States
• In a reaction, we often use symbols to represent the physical state of
the reactants and products
• Look at the reaction below when sodium metal reacts with water:
Na(s) + H2O(l)
H2(g) + NaOH(aq)
• The symbol (s) tells us that Sodium (Na) is in the solid
state
• The symbol (l) tells us the water (H2O) is in the liquid
state
• The symbol (g) tells us the hydrogen (H2) is in the
gaseous state
• Finally, the symbol (aq) tells us that sodium hydroxide
(NaOH) is aqueous or dissolved in water
Symbol
State
(s)
solid
(l)
(g)
(aq)
liquid
gas
aqueous
What do the symbols represent in a
chemical equation?
• The symbols represent the physical state of the
reactants and products
Symbol
State
solid
Na(s) + H2O(l)
H2(g) + NaOH(aq) (s)
(l)
(g)
(aq)
liquid
gas
aqueous
or dissolved
in water
Summary
(you can always write your own summary)
• Explain the Law of Conservation of Mass in your own words
and apply it to chemical reactions:
• What is the difference between the reactants and products
in a chemical reaction?
• Describe the process of balancing chemical reactions, be
sure to explain how you count atoms on both sides of the
equation
• What can you not change when balancing chemical
reactions?
• Is the reaction below balanced? Explain why or why not:
K + Cl2 KCl
Slide 13
UNIT: Chemical Reactions
TOPIC: Properties of Reactions
Objectives: Lesson 1 of 3
•
•
•
•
To learn how we recognize a chemical reaction has took place
To learn what a chemical reactions is
To learn how we balance chemical equations
To learn the symbols for each physical state in a chemical
reaction
Quickwrite
In 1-2 sentences answer one of the questions below:
• What sort of clues do think indicate that a chemical reaction is
happening in your car engine????
• What sort of clues indicate a chemical reaction when you drop a
piece of alka selzter in water????
• What are some by products produced when your body breaks
down sugar, C6H12O6????? What are some clues that this
reaction is occuring in your body????? Hint: think of
temperature!!!!
Evidence for a Chemical Reaction
• How do you know a chemical reaction has occurred?
• Chemists look for visual clues such a color or heat
change, a solid forms, bubbles are produced, a flame
occurs
• However, reactions are not always visible
• Sometimes the only signal that a reaction is occurring is
a change in temperature as heat is produced
What are some clues that a
chemical reaction has occurred?
•
•
•
•
•
A color change
A solid forms
Bubbles form
A heat change
A flame is produced
Chemical Reactions
• Chemists have learned that a chemical change always involves a
rearrangement of the ways in which atoms are grouped and combine
with one another
• For example, consider the reaction that occurs with your laboratory
bunsen burners
• In this reaction, methane (CH4) reacts with oxygen (O2) in the air
• As you know, a flame is produce and heat is released
• As the atoms rearrange themselves, two new chemicals are produced
carbon dioxide (CO2), and water (H2O)
CH4 + O2
CO2 + H2O
Chemical
Reactions
Such a change is called a chemical reaction
•
• Notice, the atoms were rearranged, Oxygen combined with Carbon and
Hydrogen to produce 2 new chemicals: Water & Carbon Dioxide
• Chemical reactions obey the Law of Conservation of Matter which states: Atoms
cannot be destroyed, they can only be rearranged
CH4 + O2
CO2
Methane (CH4)
Water(H
Carbon
Dioxide
2O) (CO2)
Oxygen(O2)
H2O
What is a Chemical Reaction?
• A chemical reaction is the change that occurs when
atoms rearrange themselves and form new
compounds
• Chemical reactions obey the first LAW of
conservation of MASS or MATTER which states:
Atoms and matter cannot be created or destroyed,
they can only be rearranged
Chemical Equations
• We represent chemical reactions by writing a
chemical equation in which the chemicals
present before the reaction are on the left of
the arrow, and the chemicals formed by the
reaction are on the right of the arrow
• The arrow indicates the direction of the
change CH4 + O2
CO2 + H2O
Chemical Equations
• In the reaction of methane with oxygen, we have:
CH4 + O2
CO2 + H2O
Reactants
Products
• The chemicals present on the left side of the
equation are known as the reactants
• The chemicals present on the right side of the
equation are known as the products
What is a Chemical Equation?
• An equation that uses the formulas of chemicals
compounds and elements to show the reactants and
products in a chemical change
• Chemicals present before the reaction are on the left of
the arrow (reactants), and the chemicals formed by the
reaction are on the right of the arrow (products)
Ex: CH4 + O2
CO2 + H2O
Balancing Chemical Reactions
• It is important to realize that in a chemical
reaction, atoms are neither created nor
destroyed
• In other words, their must be the same
number of each type of atom on the product
side as on the reactant side of the arrow
••
•
•
•
Balancing Chemical Reactions
In
other
words,
the
reaction
and
table
below
show
Oxygen
Remember,
atoms
beatoms
created
or
destroyed
in
chemical
reactions,
We
can
fix
this
by
putting
in
1atoms,
more
Oxygen
molecule
on1inthe
left
By
the
number
you
can
see
that
the
chemical
Notice,
there
are
2cannot
Oxygen
on
left
side
and
3that
Oxygen
atoms
on
We
group
molecules
by
putting
coefficients
front
ofatom
them:
Thecounting
reaction
below
is together
notof
balanced
is
created
and
2and
Hydrogen
atoms
are
destroyed
they
can only
be
rearranged!
(reactant)
side
1 more
Water
molecule
on
theleft
right
(product)
side
the
right
side;
4byHydrogen
the
side
and 2 apart:
equation
is
balanced
andare
shows
the
actual
numbers
molecules
We can
see
it isalso
notthere
balanced
taking
theonreactants
&ofproducts
Therefore,
the
reaction
cannot
way!
total in
number
of
atoms
musthappen
be
thethis
same
on both
sides
of the
arrow
The
table
now
has
equal
number
of atoms
on
both
sides
of the
equation
Hydrogen
on
the
right
side
involved
this
reaction
CH4
O+2 +2 O2
CO2
H+2+O +2H2O
H
H CH
H
O O
O C O
H OH
O O
Left
Reactant Side
C=
O=
1
2
4
H=
4
9
7
6
9
Total Number of Atoms
Right
H OH
Product Side
O=
1
34
H=
42
C=
Balancing Chemical Reactions
••••• We
In
other
can
fixwords,
this
by
putting
reaction
and
more
table
Water
molecule
show
that
on
the
1front
Oxygen
left(reactant)
atom
By
counting
the
number
of
you
can
see
the
chemical
Remember,
atoms
cannot
be1atoms,
created
orbelow
destroyed
in
chemical
reactions,
group
molecules
byon
putting
coefficients
in
ofon
them:
Notice,
there
is
1the
Oxygen
atoms
left
side
and
2that
Oxygen
atoms
The
reaction
below
istogether
notin
balanced
is
created
and
1only
Hydrogen
molecule
on
the
side and
they
cansee
rearranged!
equation
ismore
balanced
andthe
shows
actual
numbers
atoms
the
right
side;
therefore
chemical
equation
is NOT of
balanced
• side
We
can
it be
is
NOT
balanced
bythe
taking
theright(product)
reactants
& products
•• The
Therefore,
table
thehas
reaction
equal
cannot
number
of
onway!
both
sides
of the
equation
The
total now
number
of
atoms
musthappen
beatoms
the this
same
on both
sides
of the
arrow
molecules
involved
in
this
reaction
apart:
2 H2
H2O + 2 H2O
H OH
H OH
Left
Reactant Side
O=
1
2
42
H=
H H
3
6
6
4
H H
O O
Right
Product Side
O=
2
24
H=
Total Number of Atoms
H+2 + O2
Subscripts and Coefficients
• When balancing chemical equations, it is important to note
that the subscripts can never change
• For example, in the equation below, the subscript of 4 in
methane cannot be changed, neither can the subscripts 2 in
Oxygen, Carbon dioxide and Water
CH4 + 2 O2
CO2 + 2H2O
• Only coefficients can be added by putting whole numbers in
front of the compounds when balancing chemical reactions
How Do we Balance Chemical Equations?
• By placing coefficients in front of each molecule
or compound
• Subscripts cannot be changed!
• Ex: CH4 + 2O2 CO2 + 2H2O
Balancing Chemical Equations
Remember: When balancing chemical equations, it is important to
note that the subscripts can never change!!!!
2
___O
___O
3
2
3
___
2 Mg + ___ O2
___
2 MgO
Practice:
Determine how many atoms of each element are in
each compound below:
1)
2)
3)
4)
2 Na + ___ Cl
___
2
4 Fe + ___
3 O
___
2
___
4 Al + ___
3 O2
2 Na + ___ F
___
2
2
___
NaCl
2 Fe O
___
2 3
___
2 Al2O3
2 NaF
___
Physical States
• In a reaction, we often use symbols to represent the physical state of
the reactants and products
• Look at the reaction below when sodium metal reacts with water:
Na(s) + H2O(l)
H2(g) + NaOH(aq)
• The symbol (s) tells us that Sodium (Na) is in the solid
state
• The symbol (l) tells us the water (H2O) is in the liquid
state
• The symbol (g) tells us the hydrogen (H2) is in the
gaseous state
• Finally, the symbol (aq) tells us that sodium hydroxide
(NaOH) is aqueous or dissolved in water
Symbol
State
(s)
solid
(l)
(g)
(aq)
liquid
gas
aqueous
What do the symbols represent in a
chemical equation?
• The symbols represent the physical state of the
reactants and products
Symbol
State
solid
Na(s) + H2O(l)
H2(g) + NaOH(aq) (s)
(l)
(g)
(aq)
liquid
gas
aqueous
or dissolved
in water
Summary
(you can always write your own summary)
• Explain the Law of Conservation of Mass in your own words
and apply it to chemical reactions:
• What is the difference between the reactants and products
in a chemical reaction?
• Describe the process of balancing chemical reactions, be
sure to explain how you count atoms on both sides of the
equation
• What can you not change when balancing chemical
reactions?
• Is the reaction below balanced? Explain why or why not:
K + Cl2 KCl
Slide 14
UNIT: Chemical Reactions
TOPIC: Properties of Reactions
Objectives: Lesson 1 of 3
•
•
•
•
To learn how we recognize a chemical reaction has took place
To learn what a chemical reactions is
To learn how we balance chemical equations
To learn the symbols for each physical state in a chemical
reaction
Quickwrite
In 1-2 sentences answer one of the questions below:
• What sort of clues do think indicate that a chemical reaction is
happening in your car engine????
• What sort of clues indicate a chemical reaction when you drop a
piece of alka selzter in water????
• What are some by products produced when your body breaks
down sugar, C6H12O6????? What are some clues that this
reaction is occuring in your body????? Hint: think of
temperature!!!!
Evidence for a Chemical Reaction
• How do you know a chemical reaction has occurred?
• Chemists look for visual clues such a color or heat
change, a solid forms, bubbles are produced, a flame
occurs
• However, reactions are not always visible
• Sometimes the only signal that a reaction is occurring is
a change in temperature as heat is produced
What are some clues that a
chemical reaction has occurred?
•
•
•
•
•
A color change
A solid forms
Bubbles form
A heat change
A flame is produced
Chemical Reactions
• Chemists have learned that a chemical change always involves a
rearrangement of the ways in which atoms are grouped and combine
with one another
• For example, consider the reaction that occurs with your laboratory
bunsen burners
• In this reaction, methane (CH4) reacts with oxygen (O2) in the air
• As you know, a flame is produce and heat is released
• As the atoms rearrange themselves, two new chemicals are produced
carbon dioxide (CO2), and water (H2O)
CH4 + O2
CO2 + H2O
Chemical
Reactions
Such a change is called a chemical reaction
•
• Notice, the atoms were rearranged, Oxygen combined with Carbon and
Hydrogen to produce 2 new chemicals: Water & Carbon Dioxide
• Chemical reactions obey the Law of Conservation of Matter which states: Atoms
cannot be destroyed, they can only be rearranged
CH4 + O2
CO2
Methane (CH4)
Water(H
Carbon
Dioxide
2O) (CO2)
Oxygen(O2)
H2O
What is a Chemical Reaction?
• A chemical reaction is the change that occurs when
atoms rearrange themselves and form new
compounds
• Chemical reactions obey the first LAW of
conservation of MASS or MATTER which states:
Atoms and matter cannot be created or destroyed,
they can only be rearranged
Chemical Equations
• We represent chemical reactions by writing a
chemical equation in which the chemicals
present before the reaction are on the left of
the arrow, and the chemicals formed by the
reaction are on the right of the arrow
• The arrow indicates the direction of the
change CH4 + O2
CO2 + H2O
Chemical Equations
• In the reaction of methane with oxygen, we have:
CH4 + O2
CO2 + H2O
Reactants
Products
• The chemicals present on the left side of the
equation are known as the reactants
• The chemicals present on the right side of the
equation are known as the products
What is a Chemical Equation?
• An equation that uses the formulas of chemicals
compounds and elements to show the reactants and
products in a chemical change
• Chemicals present before the reaction are on the left of
the arrow (reactants), and the chemicals formed by the
reaction are on the right of the arrow (products)
Ex: CH4 + O2
CO2 + H2O
Balancing Chemical Reactions
• It is important to realize that in a chemical
reaction, atoms are neither created nor
destroyed
• In other words, their must be the same
number of each type of atom on the product
side as on the reactant side of the arrow
••
•
•
•
Balancing Chemical Reactions
In
other
words,
the
reaction
and
table
below
show
Oxygen
Remember,
atoms
beatoms
created
or
destroyed
in
chemical
reactions,
We
can
fix
this
by
putting
in
1atoms,
more
Oxygen
molecule
on1inthe
left
By
the
number
you
can
see
that
the
chemical
Notice,
there
are
2cannot
Oxygen
on
left
side
and
3that
Oxygen
atoms
on
We
group
molecules
by
putting
coefficients
front
ofatom
them:
Thecounting
reaction
below
is together
notof
balanced
is
created
and
2and
Hydrogen
atoms
are
destroyed
they
can only
be
rearranged!
(reactant)
side
1 more
Water
molecule
on
theleft
right
(product)
side
the
right
side;
4byHydrogen
the
side
and 2 apart:
equation
is
balanced
andare
shows
the
actual
numbers
molecules
We can
see
it isalso
notthere
balanced
taking
theonreactants
&ofproducts
Therefore,
the
reaction
cannot
way!
total in
number
of
atoms
musthappen
be
thethis
same
on both
sides
of the
arrow
The
table
now
has
equal
number
of atoms
on
both
sides
of the
equation
Hydrogen
on
the
right
side
involved
this
reaction
CH4
O+2 +2 O2
CO2
H+2+O +2H2O
H
H CH
H
O O
O C O
H OH
O O
Left
Reactant Side
C=
O=
1
2
4
H=
4
9
7
6
9
Total Number of Atoms
Right
H OH
Product Side
O=
1
34
H=
42
C=
Balancing Chemical Reactions
••••• We
In
other
can
fixwords,
this
by
putting
reaction
and
more
table
Water
molecule
show
that
on
the
1front
Oxygen
left(reactant)
atom
By
counting
the
number
of
you
can
see
the
chemical
Remember,
atoms
cannot
be1atoms,
created
orbelow
destroyed
in
chemical
reactions,
group
molecules
byon
putting
coefficients
in
ofon
them:
Notice,
there
is
1the
Oxygen
atoms
left
side
and
2that
Oxygen
atoms
The
reaction
below
istogether
notin
balanced
is
created
and
1only
Hydrogen
molecule
on
the
side and
they
cansee
rearranged!
equation
ismore
balanced
andthe
shows
actual
numbers
atoms
the
right
side;
therefore
chemical
equation
is NOT of
balanced
• side
We
can
it be
is
NOT
balanced
bythe
taking
theright(product)
reactants
& products
•• The
Therefore,
table
thehas
reaction
equal
cannot
number
of
onway!
both
sides
of the
equation
The
total now
number
of
atoms
musthappen
beatoms
the this
same
on both
sides
of the
arrow
molecules
involved
in
this
reaction
apart:
2 H2
H2O + 2 H2O
H OH
H OH
Left
Reactant Side
O=
1
2
42
H=
H H
3
6
6
4
H H
O O
Right
Product Side
O=
2
24
H=
Total Number of Atoms
H+2 + O2
Subscripts and Coefficients
• When balancing chemical equations, it is important to note
that the subscripts can never change
• For example, in the equation below, the subscript of 4 in
methane cannot be changed, neither can the subscripts 2 in
Oxygen, Carbon dioxide and Water
CH4 + 2 O2
CO2 + 2H2O
• Only coefficients can be added by putting whole numbers in
front of the compounds when balancing chemical reactions
How Do we Balance Chemical Equations?
• By placing coefficients in front of each molecule
or compound
• Subscripts cannot be changed!
• Ex: CH4 + 2O2 CO2 + 2H2O
Balancing Chemical Equations
Remember: When balancing chemical equations, it is important to
note that the subscripts can never change!!!!
2
___O
___O
3
2
3
___
2 Mg + ___ O2
___
2 MgO
Practice:
Determine how many atoms of each element are in
each compound below:
1)
2)
3)
4)
2 Na + ___ Cl
___
2
4 Fe + ___
3 O
___
2
___
4 Al + ___
3 O2
2 Na + ___ F
___
2
2
___
NaCl
2 Fe O
___
2 3
___
2 Al2O3
2 NaF
___
Physical States
• In a reaction, we often use symbols to represent the physical state of
the reactants and products
• Look at the reaction below when sodium metal reacts with water:
Na(s) + H2O(l)
H2(g) + NaOH(aq)
• The symbol (s) tells us that Sodium (Na) is in the solid
state
• The symbol (l) tells us the water (H2O) is in the liquid
state
• The symbol (g) tells us the hydrogen (H2) is in the
gaseous state
• Finally, the symbol (aq) tells us that sodium hydroxide
(NaOH) is aqueous or dissolved in water
Symbol
State
(s)
solid
(l)
(g)
(aq)
liquid
gas
aqueous
What do the symbols represent in a
chemical equation?
• The symbols represent the physical state of the
reactants and products
Symbol
State
solid
Na(s) + H2O(l)
H2(g) + NaOH(aq) (s)
(l)
(g)
(aq)
liquid
gas
aqueous
or dissolved
in water
Summary
(you can always write your own summary)
• Explain the Law of Conservation of Mass in your own words
and apply it to chemical reactions:
• What is the difference between the reactants and products
in a chemical reaction?
• Describe the process of balancing chemical reactions, be
sure to explain how you count atoms on both sides of the
equation
• What can you not change when balancing chemical
reactions?
• Is the reaction below balanced? Explain why or why not:
K + Cl2 KCl
Slide 15
UNIT: Chemical Reactions
TOPIC: Properties of Reactions
Objectives: Lesson 1 of 3
•
•
•
•
To learn how we recognize a chemical reaction has took place
To learn what a chemical reactions is
To learn how we balance chemical equations
To learn the symbols for each physical state in a chemical
reaction
Quickwrite
In 1-2 sentences answer one of the questions below:
• What sort of clues do think indicate that a chemical reaction is
happening in your car engine????
• What sort of clues indicate a chemical reaction when you drop a
piece of alka selzter in water????
• What are some by products produced when your body breaks
down sugar, C6H12O6????? What are some clues that this
reaction is occuring in your body????? Hint: think of
temperature!!!!
Evidence for a Chemical Reaction
• How do you know a chemical reaction has occurred?
• Chemists look for visual clues such a color or heat
change, a solid forms, bubbles are produced, a flame
occurs
• However, reactions are not always visible
• Sometimes the only signal that a reaction is occurring is
a change in temperature as heat is produced
What are some clues that a
chemical reaction has occurred?
•
•
•
•
•
A color change
A solid forms
Bubbles form
A heat change
A flame is produced
Chemical Reactions
• Chemists have learned that a chemical change always involves a
rearrangement of the ways in which atoms are grouped and combine
with one another
• For example, consider the reaction that occurs with your laboratory
bunsen burners
• In this reaction, methane (CH4) reacts with oxygen (O2) in the air
• As you know, a flame is produce and heat is released
• As the atoms rearrange themselves, two new chemicals are produced
carbon dioxide (CO2), and water (H2O)
CH4 + O2
CO2 + H2O
Chemical
Reactions
Such a change is called a chemical reaction
•
• Notice, the atoms were rearranged, Oxygen combined with Carbon and
Hydrogen to produce 2 new chemicals: Water & Carbon Dioxide
• Chemical reactions obey the Law of Conservation of Matter which states: Atoms
cannot be destroyed, they can only be rearranged
CH4 + O2
CO2
Methane (CH4)
Water(H
Carbon
Dioxide
2O) (CO2)
Oxygen(O2)
H2O
What is a Chemical Reaction?
• A chemical reaction is the change that occurs when
atoms rearrange themselves and form new
compounds
• Chemical reactions obey the first LAW of
conservation of MASS or MATTER which states:
Atoms and matter cannot be created or destroyed,
they can only be rearranged
Chemical Equations
• We represent chemical reactions by writing a
chemical equation in which the chemicals
present before the reaction are on the left of
the arrow, and the chemicals formed by the
reaction are on the right of the arrow
• The arrow indicates the direction of the
change CH4 + O2
CO2 + H2O
Chemical Equations
• In the reaction of methane with oxygen, we have:
CH4 + O2
CO2 + H2O
Reactants
Products
• The chemicals present on the left side of the
equation are known as the reactants
• The chemicals present on the right side of the
equation are known as the products
What is a Chemical Equation?
• An equation that uses the formulas of chemicals
compounds and elements to show the reactants and
products in a chemical change
• Chemicals present before the reaction are on the left of
the arrow (reactants), and the chemicals formed by the
reaction are on the right of the arrow (products)
Ex: CH4 + O2
CO2 + H2O
Balancing Chemical Reactions
• It is important to realize that in a chemical
reaction, atoms are neither created nor
destroyed
• In other words, their must be the same
number of each type of atom on the product
side as on the reactant side of the arrow
••
•
•
•
Balancing Chemical Reactions
In
other
words,
the
reaction
and
table
below
show
Oxygen
Remember,
atoms
beatoms
created
or
destroyed
in
chemical
reactions,
We
can
fix
this
by
putting
in
1atoms,
more
Oxygen
molecule
on1inthe
left
By
the
number
you
can
see
that
the
chemical
Notice,
there
are
2cannot
Oxygen
on
left
side
and
3that
Oxygen
atoms
on
We
group
molecules
by
putting
coefficients
front
ofatom
them:
Thecounting
reaction
below
is together
notof
balanced
is
created
and
2and
Hydrogen
atoms
are
destroyed
they
can only
be
rearranged!
(reactant)
side
1 more
Water
molecule
on
theleft
right
(product)
side
the
right
side;
4byHydrogen
the
side
and 2 apart:
equation
is
balanced
andare
shows
the
actual
numbers
molecules
We can
see
it isalso
notthere
balanced
taking
theonreactants
&ofproducts
Therefore,
the
reaction
cannot
way!
total in
number
of
atoms
musthappen
be
thethis
same
on both
sides
of the
arrow
The
table
now
has
equal
number
of atoms
on
both
sides
of the
equation
Hydrogen
on
the
right
side
involved
this
reaction
CH4
O+2 +2 O2
CO2
H+2+O +2H2O
H
H CH
H
O O
O C O
H OH
O O
Left
Reactant Side
C=
O=
1
2
4
H=
4
9
7
6
9
Total Number of Atoms
Right
H OH
Product Side
O=
1
34
H=
42
C=
Balancing Chemical Reactions
••••• We
In
other
can
fixwords,
this
by
putting
reaction
and
more
table
Water
molecule
show
that
on
the
1front
Oxygen
left(reactant)
atom
By
counting
the
number
of
you
can
see
the
chemical
Remember,
atoms
cannot
be1atoms,
created
orbelow
destroyed
in
chemical
reactions,
group
molecules
byon
putting
coefficients
in
ofon
them:
Notice,
there
is
1the
Oxygen
atoms
left
side
and
2that
Oxygen
atoms
The
reaction
below
istogether
notin
balanced
is
created
and
1only
Hydrogen
molecule
on
the
side and
they
cansee
rearranged!
equation
ismore
balanced
andthe
shows
actual
numbers
atoms
the
right
side;
therefore
chemical
equation
is NOT of
balanced
• side
We
can
it be
is
NOT
balanced
bythe
taking
theright(product)
reactants
& products
•• The
Therefore,
table
thehas
reaction
equal
cannot
number
of
onway!
both
sides
of the
equation
The
total now
number
of
atoms
musthappen
beatoms
the this
same
on both
sides
of the
arrow
molecules
involved
in
this
reaction
apart:
2 H2
H2O + 2 H2O
H OH
H OH
Left
Reactant Side
O=
1
2
42
H=
H H
3
6
6
4
H H
O O
Right
Product Side
O=
2
24
H=
Total Number of Atoms
H+2 + O2
Subscripts and Coefficients
• When balancing chemical equations, it is important to note
that the subscripts can never change
• For example, in the equation below, the subscript of 4 in
methane cannot be changed, neither can the subscripts 2 in
Oxygen, Carbon dioxide and Water
CH4 + 2 O2
CO2 + 2H2O
• Only coefficients can be added by putting whole numbers in
front of the compounds when balancing chemical reactions
How Do we Balance Chemical Equations?
• By placing coefficients in front of each molecule
or compound
• Subscripts cannot be changed!
• Ex: CH4 + 2O2 CO2 + 2H2O
Balancing Chemical Equations
Remember: When balancing chemical equations, it is important to
note that the subscripts can never change!!!!
2
___O
___O
3
2
3
___
2 Mg + ___ O2
___
2 MgO
Practice:
Determine how many atoms of each element are in
each compound below:
1)
2)
3)
4)
2 Na + ___ Cl
___
2
4 Fe + ___
3 O
___
2
___
4 Al + ___
3 O2
2 Na + ___ F
___
2
2
___
NaCl
2 Fe O
___
2 3
___
2 Al2O3
2 NaF
___
Physical States
• In a reaction, we often use symbols to represent the physical state of
the reactants and products
• Look at the reaction below when sodium metal reacts with water:
Na(s) + H2O(l)
H2(g) + NaOH(aq)
• The symbol (s) tells us that Sodium (Na) is in the solid
state
• The symbol (l) tells us the water (H2O) is in the liquid
state
• The symbol (g) tells us the hydrogen (H2) is in the
gaseous state
• Finally, the symbol (aq) tells us that sodium hydroxide
(NaOH) is aqueous or dissolved in water
Symbol
State
(s)
solid
(l)
(g)
(aq)
liquid
gas
aqueous
What do the symbols represent in a
chemical equation?
• The symbols represent the physical state of the
reactants and products
Symbol
State
solid
Na(s) + H2O(l)
H2(g) + NaOH(aq) (s)
(l)
(g)
(aq)
liquid
gas
aqueous
or dissolved
in water
Summary
(you can always write your own summary)
• Explain the Law of Conservation of Mass in your own words
and apply it to chemical reactions:
• What is the difference between the reactants and products
in a chemical reaction?
• Describe the process of balancing chemical reactions, be
sure to explain how you count atoms on both sides of the
equation
• What can you not change when balancing chemical
reactions?
• Is the reaction below balanced? Explain why or why not:
K + Cl2 KCl
Slide 16
UNIT: Chemical Reactions
TOPIC: Properties of Reactions
Objectives: Lesson 1 of 3
•
•
•
•
To learn how we recognize a chemical reaction has took place
To learn what a chemical reactions is
To learn how we balance chemical equations
To learn the symbols for each physical state in a chemical
reaction
Quickwrite
In 1-2 sentences answer one of the questions below:
• What sort of clues do think indicate that a chemical reaction is
happening in your car engine????
• What sort of clues indicate a chemical reaction when you drop a
piece of alka selzter in water????
• What are some by products produced when your body breaks
down sugar, C6H12O6????? What are some clues that this
reaction is occuring in your body????? Hint: think of
temperature!!!!
Evidence for a Chemical Reaction
• How do you know a chemical reaction has occurred?
• Chemists look for visual clues such a color or heat
change, a solid forms, bubbles are produced, a flame
occurs
• However, reactions are not always visible
• Sometimes the only signal that a reaction is occurring is
a change in temperature as heat is produced
What are some clues that a
chemical reaction has occurred?
•
•
•
•
•
A color change
A solid forms
Bubbles form
A heat change
A flame is produced
Chemical Reactions
• Chemists have learned that a chemical change always involves a
rearrangement of the ways in which atoms are grouped and combine
with one another
• For example, consider the reaction that occurs with your laboratory
bunsen burners
• In this reaction, methane (CH4) reacts with oxygen (O2) in the air
• As you know, a flame is produce and heat is released
• As the atoms rearrange themselves, two new chemicals are produced
carbon dioxide (CO2), and water (H2O)
CH4 + O2
CO2 + H2O
Chemical
Reactions
Such a change is called a chemical reaction
•
• Notice, the atoms were rearranged, Oxygen combined with Carbon and
Hydrogen to produce 2 new chemicals: Water & Carbon Dioxide
• Chemical reactions obey the Law of Conservation of Matter which states: Atoms
cannot be destroyed, they can only be rearranged
CH4 + O2
CO2
Methane (CH4)
Water(H
Carbon
Dioxide
2O) (CO2)
Oxygen(O2)
H2O
What is a Chemical Reaction?
• A chemical reaction is the change that occurs when
atoms rearrange themselves and form new
compounds
• Chemical reactions obey the first LAW of
conservation of MASS or MATTER which states:
Atoms and matter cannot be created or destroyed,
they can only be rearranged
Chemical Equations
• We represent chemical reactions by writing a
chemical equation in which the chemicals
present before the reaction are on the left of
the arrow, and the chemicals formed by the
reaction are on the right of the arrow
• The arrow indicates the direction of the
change CH4 + O2
CO2 + H2O
Chemical Equations
• In the reaction of methane with oxygen, we have:
CH4 + O2
CO2 + H2O
Reactants
Products
• The chemicals present on the left side of the
equation are known as the reactants
• The chemicals present on the right side of the
equation are known as the products
What is a Chemical Equation?
• An equation that uses the formulas of chemicals
compounds and elements to show the reactants and
products in a chemical change
• Chemicals present before the reaction are on the left of
the arrow (reactants), and the chemicals formed by the
reaction are on the right of the arrow (products)
Ex: CH4 + O2
CO2 + H2O
Balancing Chemical Reactions
• It is important to realize that in a chemical
reaction, atoms are neither created nor
destroyed
• In other words, their must be the same
number of each type of atom on the product
side as on the reactant side of the arrow
••
•
•
•
Balancing Chemical Reactions
In
other
words,
the
reaction
and
table
below
show
Oxygen
Remember,
atoms
beatoms
created
or
destroyed
in
chemical
reactions,
We
can
fix
this
by
putting
in
1atoms,
more
Oxygen
molecule
on1inthe
left
By
the
number
you
can
see
that
the
chemical
Notice,
there
are
2cannot
Oxygen
on
left
side
and
3that
Oxygen
atoms
on
We
group
molecules
by
putting
coefficients
front
ofatom
them:
Thecounting
reaction
below
is together
notof
balanced
is
created
and
2and
Hydrogen
atoms
are
destroyed
they
can only
be
rearranged!
(reactant)
side
1 more
Water
molecule
on
theleft
right
(product)
side
the
right
side;
4byHydrogen
the
side
and 2 apart:
equation
is
balanced
andare
shows
the
actual
numbers
molecules
We can
see
it isalso
notthere
balanced
taking
theonreactants
&ofproducts
Therefore,
the
reaction
cannot
way!
total in
number
of
atoms
musthappen
be
thethis
same
on both
sides
of the
arrow
The
table
now
has
equal
number
of atoms
on
both
sides
of the
equation
Hydrogen
on
the
right
side
involved
this
reaction
CH4
O+2 +2 O2
CO2
H+2+O +2H2O
H
H CH
H
O O
O C O
H OH
O O
Left
Reactant Side
C=
O=
1
2
4
H=
4
9
7
6
9
Total Number of Atoms
Right
H OH
Product Side
O=
1
34
H=
42
C=
Balancing Chemical Reactions
••••• We
In
other
can
fixwords,
this
by
putting
reaction
and
more
table
Water
molecule
show
that
on
the
1front
Oxygen
left(reactant)
atom
By
counting
the
number
of
you
can
see
the
chemical
Remember,
atoms
cannot
be1atoms,
created
orbelow
destroyed
in
chemical
reactions,
group
molecules
byon
putting
coefficients
in
ofon
them:
Notice,
there
is
1the
Oxygen
atoms
left
side
and
2that
Oxygen
atoms
The
reaction
below
istogether
notin
balanced
is
created
and
1only
Hydrogen
molecule
on
the
side and
they
cansee
rearranged!
equation
ismore
balanced
andthe
shows
actual
numbers
atoms
the
right
side;
therefore
chemical
equation
is NOT of
balanced
• side
We
can
it be
is
NOT
balanced
bythe
taking
theright(product)
reactants
& products
•• The
Therefore,
table
thehas
reaction
equal
cannot
number
of
onway!
both
sides
of the
equation
The
total now
number
of
atoms
musthappen
beatoms
the this
same
on both
sides
of the
arrow
molecules
involved
in
this
reaction
apart:
2 H2
H2O + 2 H2O
H OH
H OH
Left
Reactant Side
O=
1
2
42
H=
H H
3
6
6
4
H H
O O
Right
Product Side
O=
2
24
H=
Total Number of Atoms
H+2 + O2
Subscripts and Coefficients
• When balancing chemical equations, it is important to note
that the subscripts can never change
• For example, in the equation below, the subscript of 4 in
methane cannot be changed, neither can the subscripts 2 in
Oxygen, Carbon dioxide and Water
CH4 + 2 O2
CO2 + 2H2O
• Only coefficients can be added by putting whole numbers in
front of the compounds when balancing chemical reactions
How Do we Balance Chemical Equations?
• By placing coefficients in front of each molecule
or compound
• Subscripts cannot be changed!
• Ex: CH4 + 2O2 CO2 + 2H2O
Balancing Chemical Equations
Remember: When balancing chemical equations, it is important to
note that the subscripts can never change!!!!
2
___O
___O
3
2
3
___
2 Mg + ___ O2
___
2 MgO
Practice:
Determine how many atoms of each element are in
each compound below:
1)
2)
3)
4)
2 Na + ___ Cl
___
2
4 Fe + ___
3 O
___
2
___
4 Al + ___
3 O2
2 Na + ___ F
___
2
2
___
NaCl
2 Fe O
___
2 3
___
2 Al2O3
2 NaF
___
Physical States
• In a reaction, we often use symbols to represent the physical state of
the reactants and products
• Look at the reaction below when sodium metal reacts with water:
Na(s) + H2O(l)
H2(g) + NaOH(aq)
• The symbol (s) tells us that Sodium (Na) is in the solid
state
• The symbol (l) tells us the water (H2O) is in the liquid
state
• The symbol (g) tells us the hydrogen (H2) is in the
gaseous state
• Finally, the symbol (aq) tells us that sodium hydroxide
(NaOH) is aqueous or dissolved in water
Symbol
State
(s)
solid
(l)
(g)
(aq)
liquid
gas
aqueous
What do the symbols represent in a
chemical equation?
• The symbols represent the physical state of the
reactants and products
Symbol
State
solid
Na(s) + H2O(l)
H2(g) + NaOH(aq) (s)
(l)
(g)
(aq)
liquid
gas
aqueous
or dissolved
in water
Summary
(you can always write your own summary)
• Explain the Law of Conservation of Mass in your own words
and apply it to chemical reactions:
• What is the difference between the reactants and products
in a chemical reaction?
• Describe the process of balancing chemical reactions, be
sure to explain how you count atoms on both sides of the
equation
• What can you not change when balancing chemical
reactions?
• Is the reaction below balanced? Explain why or why not:
K + Cl2 KCl
Slide 17
UNIT: Chemical Reactions
TOPIC: Properties of Reactions
Objectives: Lesson 1 of 3
•
•
•
•
To learn how we recognize a chemical reaction has took place
To learn what a chemical reactions is
To learn how we balance chemical equations
To learn the symbols for each physical state in a chemical
reaction
Quickwrite
In 1-2 sentences answer one of the questions below:
• What sort of clues do think indicate that a chemical reaction is
happening in your car engine????
• What sort of clues indicate a chemical reaction when you drop a
piece of alka selzter in water????
• What are some by products produced when your body breaks
down sugar, C6H12O6????? What are some clues that this
reaction is occuring in your body????? Hint: think of
temperature!!!!
Evidence for a Chemical Reaction
• How do you know a chemical reaction has occurred?
• Chemists look for visual clues such a color or heat
change, a solid forms, bubbles are produced, a flame
occurs
• However, reactions are not always visible
• Sometimes the only signal that a reaction is occurring is
a change in temperature as heat is produced
What are some clues that a
chemical reaction has occurred?
•
•
•
•
•
A color change
A solid forms
Bubbles form
A heat change
A flame is produced
Chemical Reactions
• Chemists have learned that a chemical change always involves a
rearrangement of the ways in which atoms are grouped and combine
with one another
• For example, consider the reaction that occurs with your laboratory
bunsen burners
• In this reaction, methane (CH4) reacts with oxygen (O2) in the air
• As you know, a flame is produce and heat is released
• As the atoms rearrange themselves, two new chemicals are produced
carbon dioxide (CO2), and water (H2O)
CH4 + O2
CO2 + H2O
Chemical
Reactions
Such a change is called a chemical reaction
•
• Notice, the atoms were rearranged, Oxygen combined with Carbon and
Hydrogen to produce 2 new chemicals: Water & Carbon Dioxide
• Chemical reactions obey the Law of Conservation of Matter which states: Atoms
cannot be destroyed, they can only be rearranged
CH4 + O2
CO2
Methane (CH4)
Water(H
Carbon
Dioxide
2O) (CO2)
Oxygen(O2)
H2O
What is a Chemical Reaction?
• A chemical reaction is the change that occurs when
atoms rearrange themselves and form new
compounds
• Chemical reactions obey the first LAW of
conservation of MASS or MATTER which states:
Atoms and matter cannot be created or destroyed,
they can only be rearranged
Chemical Equations
• We represent chemical reactions by writing a
chemical equation in which the chemicals
present before the reaction are on the left of
the arrow, and the chemicals formed by the
reaction are on the right of the arrow
• The arrow indicates the direction of the
change CH4 + O2
CO2 + H2O
Chemical Equations
• In the reaction of methane with oxygen, we have:
CH4 + O2
CO2 + H2O
Reactants
Products
• The chemicals present on the left side of the
equation are known as the reactants
• The chemicals present on the right side of the
equation are known as the products
What is a Chemical Equation?
• An equation that uses the formulas of chemicals
compounds and elements to show the reactants and
products in a chemical change
• Chemicals present before the reaction are on the left of
the arrow (reactants), and the chemicals formed by the
reaction are on the right of the arrow (products)
Ex: CH4 + O2
CO2 + H2O
Balancing Chemical Reactions
• It is important to realize that in a chemical
reaction, atoms are neither created nor
destroyed
• In other words, their must be the same
number of each type of atom on the product
side as on the reactant side of the arrow
••
•
•
•
Balancing Chemical Reactions
In
other
words,
the
reaction
and
table
below
show
Oxygen
Remember,
atoms
beatoms
created
or
destroyed
in
chemical
reactions,
We
can
fix
this
by
putting
in
1atoms,
more
Oxygen
molecule
on1inthe
left
By
the
number
you
can
see
that
the
chemical
Notice,
there
are
2cannot
Oxygen
on
left
side
and
3that
Oxygen
atoms
on
We
group
molecules
by
putting
coefficients
front
ofatom
them:
Thecounting
reaction
below
is together
notof
balanced
is
created
and
2and
Hydrogen
atoms
are
destroyed
they
can only
be
rearranged!
(reactant)
side
1 more
Water
molecule
on
theleft
right
(product)
side
the
right
side;
4byHydrogen
the
side
and 2 apart:
equation
is
balanced
andare
shows
the
actual
numbers
molecules
We can
see
it isalso
notthere
balanced
taking
theonreactants
&ofproducts
Therefore,
the
reaction
cannot
way!
total in
number
of
atoms
musthappen
be
thethis
same
on both
sides
of the
arrow
The
table
now
has
equal
number
of atoms
on
both
sides
of the
equation
Hydrogen
on
the
right
side
involved
this
reaction
CH4
O+2 +2 O2
CO2
H+2+O +2H2O
H
H CH
H
O O
O C O
H OH
O O
Left
Reactant Side
C=
O=
1
2
4
H=
4
9
7
6
9
Total Number of Atoms
Right
H OH
Product Side
O=
1
34
H=
42
C=
Balancing Chemical Reactions
••••• We
In
other
can
fixwords,
this
by
putting
reaction
and
more
table
Water
molecule
show
that
on
the
1front
Oxygen
left(reactant)
atom
By
counting
the
number
of
you
can
see
the
chemical
Remember,
atoms
cannot
be1atoms,
created
orbelow
destroyed
in
chemical
reactions,
group
molecules
byon
putting
coefficients
in
ofon
them:
Notice,
there
is
1the
Oxygen
atoms
left
side
and
2that
Oxygen
atoms
The
reaction
below
istogether
notin
balanced
is
created
and
1only
Hydrogen
molecule
on
the
side and
they
cansee
rearranged!
equation
ismore
balanced
andthe
shows
actual
numbers
atoms
the
right
side;
therefore
chemical
equation
is NOT of
balanced
• side
We
can
it be
is
NOT
balanced
bythe
taking
theright(product)
reactants
& products
•• The
Therefore,
table
thehas
reaction
equal
cannot
number
of
onway!
both
sides
of the
equation
The
total now
number
of
atoms
musthappen
beatoms
the this
same
on both
sides
of the
arrow
molecules
involved
in
this
reaction
apart:
2 H2
H2O + 2 H2O
H OH
H OH
Left
Reactant Side
O=
1
2
42
H=
H H
3
6
6
4
H H
O O
Right
Product Side
O=
2
24
H=
Total Number of Atoms
H+2 + O2
Subscripts and Coefficients
• When balancing chemical equations, it is important to note
that the subscripts can never change
• For example, in the equation below, the subscript of 4 in
methane cannot be changed, neither can the subscripts 2 in
Oxygen, Carbon dioxide and Water
CH4 + 2 O2
CO2 + 2H2O
• Only coefficients can be added by putting whole numbers in
front of the compounds when balancing chemical reactions
How Do we Balance Chemical Equations?
• By placing coefficients in front of each molecule
or compound
• Subscripts cannot be changed!
• Ex: CH4 + 2O2 CO2 + 2H2O
Balancing Chemical Equations
Remember: When balancing chemical equations, it is important to
note that the subscripts can never change!!!!
2
___O
___O
3
2
3
___
2 Mg + ___ O2
___
2 MgO
Practice:
Determine how many atoms of each element are in
each compound below:
1)
2)
3)
4)
2 Na + ___ Cl
___
2
4 Fe + ___
3 O
___
2
___
4 Al + ___
3 O2
2 Na + ___ F
___
2
2
___
NaCl
2 Fe O
___
2 3
___
2 Al2O3
2 NaF
___
Physical States
• In a reaction, we often use symbols to represent the physical state of
the reactants and products
• Look at the reaction below when sodium metal reacts with water:
Na(s) + H2O(l)
H2(g) + NaOH(aq)
• The symbol (s) tells us that Sodium (Na) is in the solid
state
• The symbol (l) tells us the water (H2O) is in the liquid
state
• The symbol (g) tells us the hydrogen (H2) is in the
gaseous state
• Finally, the symbol (aq) tells us that sodium hydroxide
(NaOH) is aqueous or dissolved in water
Symbol
State
(s)
solid
(l)
(g)
(aq)
liquid
gas
aqueous
What do the symbols represent in a
chemical equation?
• The symbols represent the physical state of the
reactants and products
Symbol
State
solid
Na(s) + H2O(l)
H2(g) + NaOH(aq) (s)
(l)
(g)
(aq)
liquid
gas
aqueous
or dissolved
in water
Summary
(you can always write your own summary)
• Explain the Law of Conservation of Mass in your own words
and apply it to chemical reactions:
• What is the difference between the reactants and products
in a chemical reaction?
• Describe the process of balancing chemical reactions, be
sure to explain how you count atoms on both sides of the
equation
• What can you not change when balancing chemical
reactions?
• Is the reaction below balanced? Explain why or why not:
K + Cl2 KCl
Slide 18
UNIT: Chemical Reactions
TOPIC: Properties of Reactions
Objectives: Lesson 1 of 3
•
•
•
•
To learn how we recognize a chemical reaction has took place
To learn what a chemical reactions is
To learn how we balance chemical equations
To learn the symbols for each physical state in a chemical
reaction
Quickwrite
In 1-2 sentences answer one of the questions below:
• What sort of clues do think indicate that a chemical reaction is
happening in your car engine????
• What sort of clues indicate a chemical reaction when you drop a
piece of alka selzter in water????
• What are some by products produced when your body breaks
down sugar, C6H12O6????? What are some clues that this
reaction is occuring in your body????? Hint: think of
temperature!!!!
Evidence for a Chemical Reaction
• How do you know a chemical reaction has occurred?
• Chemists look for visual clues such a color or heat
change, a solid forms, bubbles are produced, a flame
occurs
• However, reactions are not always visible
• Sometimes the only signal that a reaction is occurring is
a change in temperature as heat is produced
What are some clues that a
chemical reaction has occurred?
•
•
•
•
•
A color change
A solid forms
Bubbles form
A heat change
A flame is produced
Chemical Reactions
• Chemists have learned that a chemical change always involves a
rearrangement of the ways in which atoms are grouped and combine
with one another
• For example, consider the reaction that occurs with your laboratory
bunsen burners
• In this reaction, methane (CH4) reacts with oxygen (O2) in the air
• As you know, a flame is produce and heat is released
• As the atoms rearrange themselves, two new chemicals are produced
carbon dioxide (CO2), and water (H2O)
CH4 + O2
CO2 + H2O
Chemical
Reactions
Such a change is called a chemical reaction
•
• Notice, the atoms were rearranged, Oxygen combined with Carbon and
Hydrogen to produce 2 new chemicals: Water & Carbon Dioxide
• Chemical reactions obey the Law of Conservation of Matter which states: Atoms
cannot be destroyed, they can only be rearranged
CH4 + O2
CO2
Methane (CH4)
Water(H
Carbon
Dioxide
2O) (CO2)
Oxygen(O2)
H2O
What is a Chemical Reaction?
• A chemical reaction is the change that occurs when
atoms rearrange themselves and form new
compounds
• Chemical reactions obey the first LAW of
conservation of MASS or MATTER which states:
Atoms and matter cannot be created or destroyed,
they can only be rearranged
Chemical Equations
• We represent chemical reactions by writing a
chemical equation in which the chemicals
present before the reaction are on the left of
the arrow, and the chemicals formed by the
reaction are on the right of the arrow
• The arrow indicates the direction of the
change CH4 + O2
CO2 + H2O
Chemical Equations
• In the reaction of methane with oxygen, we have:
CH4 + O2
CO2 + H2O
Reactants
Products
• The chemicals present on the left side of the
equation are known as the reactants
• The chemicals present on the right side of the
equation are known as the products
What is a Chemical Equation?
• An equation that uses the formulas of chemicals
compounds and elements to show the reactants and
products in a chemical change
• Chemicals present before the reaction are on the left of
the arrow (reactants), and the chemicals formed by the
reaction are on the right of the arrow (products)
Ex: CH4 + O2
CO2 + H2O
Balancing Chemical Reactions
• It is important to realize that in a chemical
reaction, atoms are neither created nor
destroyed
• In other words, their must be the same
number of each type of atom on the product
side as on the reactant side of the arrow
••
•
•
•
Balancing Chemical Reactions
In
other
words,
the
reaction
and
table
below
show
Oxygen
Remember,
atoms
beatoms
created
or
destroyed
in
chemical
reactions,
We
can
fix
this
by
putting
in
1atoms,
more
Oxygen
molecule
on1inthe
left
By
the
number
you
can
see
that
the
chemical
Notice,
there
are
2cannot
Oxygen
on
left
side
and
3that
Oxygen
atoms
on
We
group
molecules
by
putting
coefficients
front
ofatom
them:
Thecounting
reaction
below
is together
notof
balanced
is
created
and
2and
Hydrogen
atoms
are
destroyed
they
can only
be
rearranged!
(reactant)
side
1 more
Water
molecule
on
theleft
right
(product)
side
the
right
side;
4byHydrogen
the
side
and 2 apart:
equation
is
balanced
andare
shows
the
actual
numbers
molecules
We can
see
it isalso
notthere
balanced
taking
theonreactants
&ofproducts
Therefore,
the
reaction
cannot
way!
total in
number
of
atoms
musthappen
be
thethis
same
on both
sides
of the
arrow
The
table
now
has
equal
number
of atoms
on
both
sides
of the
equation
Hydrogen
on
the
right
side
involved
this
reaction
CH4
O+2 +2 O2
CO2
H+2+O +2H2O
H
H CH
H
O O
O C O
H OH
O O
Left
Reactant Side
C=
O=
1
2
4
H=
4
9
7
6
9
Total Number of Atoms
Right
H OH
Product Side
O=
1
34
H=
42
C=
Balancing Chemical Reactions
••••• We
In
other
can
fixwords,
this
by
putting
reaction
and
more
table
Water
molecule
show
that
on
the
1front
Oxygen
left(reactant)
atom
By
counting
the
number
of
you
can
see
the
chemical
Remember,
atoms
cannot
be1atoms,
created
orbelow
destroyed
in
chemical
reactions,
group
molecules
byon
putting
coefficients
in
ofon
them:
Notice,
there
is
1the
Oxygen
atoms
left
side
and
2that
Oxygen
atoms
The
reaction
below
istogether
notin
balanced
is
created
and
1only
Hydrogen
molecule
on
the
side and
they
cansee
rearranged!
equation
ismore
balanced
andthe
shows
actual
numbers
atoms
the
right
side;
therefore
chemical
equation
is NOT of
balanced
• side
We
can
it be
is
NOT
balanced
bythe
taking
theright(product)
reactants
& products
•• The
Therefore,
table
thehas
reaction
equal
cannot
number
of
onway!
both
sides
of the
equation
The
total now
number
of
atoms
musthappen
beatoms
the this
same
on both
sides
of the
arrow
molecules
involved
in
this
reaction
apart:
2 H2
H2O + 2 H2O
H OH
H OH
Left
Reactant Side
O=
1
2
42
H=
H H
3
6
6
4
H H
O O
Right
Product Side
O=
2
24
H=
Total Number of Atoms
H+2 + O2
Subscripts and Coefficients
• When balancing chemical equations, it is important to note
that the subscripts can never change
• For example, in the equation below, the subscript of 4 in
methane cannot be changed, neither can the subscripts 2 in
Oxygen, Carbon dioxide and Water
CH4 + 2 O2
CO2 + 2H2O
• Only coefficients can be added by putting whole numbers in
front of the compounds when balancing chemical reactions
How Do we Balance Chemical Equations?
• By placing coefficients in front of each molecule
or compound
• Subscripts cannot be changed!
• Ex: CH4 + 2O2 CO2 + 2H2O
Balancing Chemical Equations
Remember: When balancing chemical equations, it is important to
note that the subscripts can never change!!!!
2
___O
___O
3
2
3
___
2 Mg + ___ O2
___
2 MgO
Practice:
Determine how many atoms of each element are in
each compound below:
1)
2)
3)
4)
2 Na + ___ Cl
___
2
4 Fe + ___
3 O
___
2
___
4 Al + ___
3 O2
2 Na + ___ F
___
2
2
___
NaCl
2 Fe O
___
2 3
___
2 Al2O3
2 NaF
___
Physical States
• In a reaction, we often use symbols to represent the physical state of
the reactants and products
• Look at the reaction below when sodium metal reacts with water:
Na(s) + H2O(l)
H2(g) + NaOH(aq)
• The symbol (s) tells us that Sodium (Na) is in the solid
state
• The symbol (l) tells us the water (H2O) is in the liquid
state
• The symbol (g) tells us the hydrogen (H2) is in the
gaseous state
• Finally, the symbol (aq) tells us that sodium hydroxide
(NaOH) is aqueous or dissolved in water
Symbol
State
(s)
solid
(l)
(g)
(aq)
liquid
gas
aqueous
What do the symbols represent in a
chemical equation?
• The symbols represent the physical state of the
reactants and products
Symbol
State
solid
Na(s) + H2O(l)
H2(g) + NaOH(aq) (s)
(l)
(g)
(aq)
liquid
gas
aqueous
or dissolved
in water
Summary
(you can always write your own summary)
• Explain the Law of Conservation of Mass in your own words
and apply it to chemical reactions:
• What is the difference between the reactants and products
in a chemical reaction?
• Describe the process of balancing chemical reactions, be
sure to explain how you count atoms on both sides of the
equation
• What can you not change when balancing chemical
reactions?
• Is the reaction below balanced? Explain why or why not:
K + Cl2 KCl
Slide 19
UNIT: Chemical Reactions
TOPIC: Properties of Reactions
Objectives: Lesson 1 of 3
•
•
•
•
To learn how we recognize a chemical reaction has took place
To learn what a chemical reactions is
To learn how we balance chemical equations
To learn the symbols for each physical state in a chemical
reaction
Quickwrite
In 1-2 sentences answer one of the questions below:
• What sort of clues do think indicate that a chemical reaction is
happening in your car engine????
• What sort of clues indicate a chemical reaction when you drop a
piece of alka selzter in water????
• What are some by products produced when your body breaks
down sugar, C6H12O6????? What are some clues that this
reaction is occuring in your body????? Hint: think of
temperature!!!!
Evidence for a Chemical Reaction
• How do you know a chemical reaction has occurred?
• Chemists look for visual clues such a color or heat
change, a solid forms, bubbles are produced, a flame
occurs
• However, reactions are not always visible
• Sometimes the only signal that a reaction is occurring is
a change in temperature as heat is produced
What are some clues that a
chemical reaction has occurred?
•
•
•
•
•
A color change
A solid forms
Bubbles form
A heat change
A flame is produced
Chemical Reactions
• Chemists have learned that a chemical change always involves a
rearrangement of the ways in which atoms are grouped and combine
with one another
• For example, consider the reaction that occurs with your laboratory
bunsen burners
• In this reaction, methane (CH4) reacts with oxygen (O2) in the air
• As you know, a flame is produce and heat is released
• As the atoms rearrange themselves, two new chemicals are produced
carbon dioxide (CO2), and water (H2O)
CH4 + O2
CO2 + H2O
Chemical
Reactions
Such a change is called a chemical reaction
•
• Notice, the atoms were rearranged, Oxygen combined with Carbon and
Hydrogen to produce 2 new chemicals: Water & Carbon Dioxide
• Chemical reactions obey the Law of Conservation of Matter which states: Atoms
cannot be destroyed, they can only be rearranged
CH4 + O2
CO2
Methane (CH4)
Water(H
Carbon
Dioxide
2O) (CO2)
Oxygen(O2)
H2O
What is a Chemical Reaction?
• A chemical reaction is the change that occurs when
atoms rearrange themselves and form new
compounds
• Chemical reactions obey the first LAW of
conservation of MASS or MATTER which states:
Atoms and matter cannot be created or destroyed,
they can only be rearranged
Chemical Equations
• We represent chemical reactions by writing a
chemical equation in which the chemicals
present before the reaction are on the left of
the arrow, and the chemicals formed by the
reaction are on the right of the arrow
• The arrow indicates the direction of the
change CH4 + O2
CO2 + H2O
Chemical Equations
• In the reaction of methane with oxygen, we have:
CH4 + O2
CO2 + H2O
Reactants
Products
• The chemicals present on the left side of the
equation are known as the reactants
• The chemicals present on the right side of the
equation are known as the products
What is a Chemical Equation?
• An equation that uses the formulas of chemicals
compounds and elements to show the reactants and
products in a chemical change
• Chemicals present before the reaction are on the left of
the arrow (reactants), and the chemicals formed by the
reaction are on the right of the arrow (products)
Ex: CH4 + O2
CO2 + H2O
Balancing Chemical Reactions
• It is important to realize that in a chemical
reaction, atoms are neither created nor
destroyed
• In other words, their must be the same
number of each type of atom on the product
side as on the reactant side of the arrow
••
•
•
•
Balancing Chemical Reactions
In
other
words,
the
reaction
and
table
below
show
Oxygen
Remember,
atoms
beatoms
created
or
destroyed
in
chemical
reactions,
We
can
fix
this
by
putting
in
1atoms,
more
Oxygen
molecule
on1inthe
left
By
the
number
you
can
see
that
the
chemical
Notice,
there
are
2cannot
Oxygen
on
left
side
and
3that
Oxygen
atoms
on
We
group
molecules
by
putting
coefficients
front
ofatom
them:
Thecounting
reaction
below
is together
notof
balanced
is
created
and
2and
Hydrogen
atoms
are
destroyed
they
can only
be
rearranged!
(reactant)
side
1 more
Water
molecule
on
theleft
right
(product)
side
the
right
side;
4byHydrogen
the
side
and 2 apart:
equation
is
balanced
andare
shows
the
actual
numbers
molecules
We can
see
it isalso
notthere
balanced
taking
theonreactants
&ofproducts
Therefore,
the
reaction
cannot
way!
total in
number
of
atoms
musthappen
be
thethis
same
on both
sides
of the
arrow
The
table
now
has
equal
number
of atoms
on
both
sides
of the
equation
Hydrogen
on
the
right
side
involved
this
reaction
CH4
O+2 +2 O2
CO2
H+2+O +2H2O
H
H CH
H
O O
O C O
H OH
O O
Left
Reactant Side
C=
O=
1
2
4
H=
4
9
7
6
9
Total Number of Atoms
Right
H OH
Product Side
O=
1
34
H=
42
C=
Balancing Chemical Reactions
••••• We
In
other
can
fixwords,
this
by
putting
reaction
and
more
table
Water
molecule
show
that
on
the
1front
Oxygen
left(reactant)
atom
By
counting
the
number
of
you
can
see
the
chemical
Remember,
atoms
cannot
be1atoms,
created
orbelow
destroyed
in
chemical
reactions,
group
molecules
byon
putting
coefficients
in
ofon
them:
Notice,
there
is
1the
Oxygen
atoms
left
side
and
2that
Oxygen
atoms
The
reaction
below
istogether
notin
balanced
is
created
and
1only
Hydrogen
molecule
on
the
side and
they
cansee
rearranged!
equation
ismore
balanced
andthe
shows
actual
numbers
atoms
the
right
side;
therefore
chemical
equation
is NOT of
balanced
• side
We
can
it be
is
NOT
balanced
bythe
taking
theright(product)
reactants
& products
•• The
Therefore,
table
thehas
reaction
equal
cannot
number
of
onway!
both
sides
of the
equation
The
total now
number
of
atoms
musthappen
beatoms
the this
same
on both
sides
of the
arrow
molecules
involved
in
this
reaction
apart:
2 H2
H2O + 2 H2O
H OH
H OH
Left
Reactant Side
O=
1
2
42
H=
H H
3
6
6
4
H H
O O
Right
Product Side
O=
2
24
H=
Total Number of Atoms
H+2 + O2
Subscripts and Coefficients
• When balancing chemical equations, it is important to note
that the subscripts can never change
• For example, in the equation below, the subscript of 4 in
methane cannot be changed, neither can the subscripts 2 in
Oxygen, Carbon dioxide and Water
CH4 + 2 O2
CO2 + 2H2O
• Only coefficients can be added by putting whole numbers in
front of the compounds when balancing chemical reactions
How Do we Balance Chemical Equations?
• By placing coefficients in front of each molecule
or compound
• Subscripts cannot be changed!
• Ex: CH4 + 2O2 CO2 + 2H2O
Balancing Chemical Equations
Remember: When balancing chemical equations, it is important to
note that the subscripts can never change!!!!
2
___O
___O
3
2
3
___
2 Mg + ___ O2
___
2 MgO
Practice:
Determine how many atoms of each element are in
each compound below:
1)
2)
3)
4)
2 Na + ___ Cl
___
2
4 Fe + ___
3 O
___
2
___
4 Al + ___
3 O2
2 Na + ___ F
___
2
2
___
NaCl
2 Fe O
___
2 3
___
2 Al2O3
2 NaF
___
Physical States
• In a reaction, we often use symbols to represent the physical state of
the reactants and products
• Look at the reaction below when sodium metal reacts with water:
Na(s) + H2O(l)
H2(g) + NaOH(aq)
• The symbol (s) tells us that Sodium (Na) is in the solid
state
• The symbol (l) tells us the water (H2O) is in the liquid
state
• The symbol (g) tells us the hydrogen (H2) is in the
gaseous state
• Finally, the symbol (aq) tells us that sodium hydroxide
(NaOH) is aqueous or dissolved in water
Symbol
State
(s)
solid
(l)
(g)
(aq)
liquid
gas
aqueous
What do the symbols represent in a
chemical equation?
• The symbols represent the physical state of the
reactants and products
Symbol
State
solid
Na(s) + H2O(l)
H2(g) + NaOH(aq) (s)
(l)
(g)
(aq)
liquid
gas
aqueous
or dissolved
in water
Summary
(you can always write your own summary)
• Explain the Law of Conservation of Mass in your own words
and apply it to chemical reactions:
• What is the difference between the reactants and products
in a chemical reaction?
• Describe the process of balancing chemical reactions, be
sure to explain how you count atoms on both sides of the
equation
• What can you not change when balancing chemical
reactions?
• Is the reaction below balanced? Explain why or why not:
K + Cl2 KCl
Slide 20
UNIT: Chemical Reactions
TOPIC: Properties of Reactions
Objectives: Lesson 1 of 3
•
•
•
•
To learn how we recognize a chemical reaction has took place
To learn what a chemical reactions is
To learn how we balance chemical equations
To learn the symbols for each physical state in a chemical
reaction
Quickwrite
In 1-2 sentences answer one of the questions below:
• What sort of clues do think indicate that a chemical reaction is
happening in your car engine????
• What sort of clues indicate a chemical reaction when you drop a
piece of alka selzter in water????
• What are some by products produced when your body breaks
down sugar, C6H12O6????? What are some clues that this
reaction is occuring in your body????? Hint: think of
temperature!!!!
Evidence for a Chemical Reaction
• How do you know a chemical reaction has occurred?
• Chemists look for visual clues such a color or heat
change, a solid forms, bubbles are produced, a flame
occurs
• However, reactions are not always visible
• Sometimes the only signal that a reaction is occurring is
a change in temperature as heat is produced
What are some clues that a
chemical reaction has occurred?
•
•
•
•
•
A color change
A solid forms
Bubbles form
A heat change
A flame is produced
Chemical Reactions
• Chemists have learned that a chemical change always involves a
rearrangement of the ways in which atoms are grouped and combine
with one another
• For example, consider the reaction that occurs with your laboratory
bunsen burners
• In this reaction, methane (CH4) reacts with oxygen (O2) in the air
• As you know, a flame is produce and heat is released
• As the atoms rearrange themselves, two new chemicals are produced
carbon dioxide (CO2), and water (H2O)
CH4 + O2
CO2 + H2O
Chemical
Reactions
Such a change is called a chemical reaction
•
• Notice, the atoms were rearranged, Oxygen combined with Carbon and
Hydrogen to produce 2 new chemicals: Water & Carbon Dioxide
• Chemical reactions obey the Law of Conservation of Matter which states: Atoms
cannot be destroyed, they can only be rearranged
CH4 + O2
CO2
Methane (CH4)
Water(H
Carbon
Dioxide
2O) (CO2)
Oxygen(O2)
H2O
What is a Chemical Reaction?
• A chemical reaction is the change that occurs when
atoms rearrange themselves and form new
compounds
• Chemical reactions obey the first LAW of
conservation of MASS or MATTER which states:
Atoms and matter cannot be created or destroyed,
they can only be rearranged
Chemical Equations
• We represent chemical reactions by writing a
chemical equation in which the chemicals
present before the reaction are on the left of
the arrow, and the chemicals formed by the
reaction are on the right of the arrow
• The arrow indicates the direction of the
change CH4 + O2
CO2 + H2O
Chemical Equations
• In the reaction of methane with oxygen, we have:
CH4 + O2
CO2 + H2O
Reactants
Products
• The chemicals present on the left side of the
equation are known as the reactants
• The chemicals present on the right side of the
equation are known as the products
What is a Chemical Equation?
• An equation that uses the formulas of chemicals
compounds and elements to show the reactants and
products in a chemical change
• Chemicals present before the reaction are on the left of
the arrow (reactants), and the chemicals formed by the
reaction are on the right of the arrow (products)
Ex: CH4 + O2
CO2 + H2O
Balancing Chemical Reactions
• It is important to realize that in a chemical
reaction, atoms are neither created nor
destroyed
• In other words, their must be the same
number of each type of atom on the product
side as on the reactant side of the arrow
••
•
•
•
Balancing Chemical Reactions
In
other
words,
the
reaction
and
table
below
show
Oxygen
Remember,
atoms
beatoms
created
or
destroyed
in
chemical
reactions,
We
can
fix
this
by
putting
in
1atoms,
more
Oxygen
molecule
on1inthe
left
By
the
number
you
can
see
that
the
chemical
Notice,
there
are
2cannot
Oxygen
on
left
side
and
3that
Oxygen
atoms
on
We
group
molecules
by
putting
coefficients
front
ofatom
them:
Thecounting
reaction
below
is together
notof
balanced
is
created
and
2and
Hydrogen
atoms
are
destroyed
they
can only
be
rearranged!
(reactant)
side
1 more
Water
molecule
on
theleft
right
(product)
side
the
right
side;
4byHydrogen
the
side
and 2 apart:
equation
is
balanced
andare
shows
the
actual
numbers
molecules
We can
see
it isalso
notthere
balanced
taking
theonreactants
&ofproducts
Therefore,
the
reaction
cannot
way!
total in
number
of
atoms
musthappen
be
thethis
same
on both
sides
of the
arrow
The
table
now
has
equal
number
of atoms
on
both
sides
of the
equation
Hydrogen
on
the
right
side
involved
this
reaction
CH4
O+2 +2 O2
CO2
H+2+O +2H2O
H
H CH
H
O O
O C O
H OH
O O
Left
Reactant Side
C=
O=
1
2
4
H=
4
9
7
6
9
Total Number of Atoms
Right
H OH
Product Side
O=
1
34
H=
42
C=
Balancing Chemical Reactions
••••• We
In
other
can
fixwords,
this
by
putting
reaction
and
more
table
Water
molecule
show
that
on
the
1front
Oxygen
left(reactant)
atom
By
counting
the
number
of
you
can
see
the
chemical
Remember,
atoms
cannot
be1atoms,
created
orbelow
destroyed
in
chemical
reactions,
group
molecules
byon
putting
coefficients
in
ofon
them:
Notice,
there
is
1the
Oxygen
atoms
left
side
and
2that
Oxygen
atoms
The
reaction
below
istogether
notin
balanced
is
created
and
1only
Hydrogen
molecule
on
the
side and
they
cansee
rearranged!
equation
ismore
balanced
andthe
shows
actual
numbers
atoms
the
right
side;
therefore
chemical
equation
is NOT of
balanced
• side
We
can
it be
is
NOT
balanced
bythe
taking
theright(product)
reactants
& products
•• The
Therefore,
table
thehas
reaction
equal
cannot
number
of
onway!
both
sides
of the
equation
The
total now
number
of
atoms
musthappen
beatoms
the this
same
on both
sides
of the
arrow
molecules
involved
in
this
reaction
apart:
2 H2
H2O + 2 H2O
H OH
H OH
Left
Reactant Side
O=
1
2
42
H=
H H
3
6
6
4
H H
O O
Right
Product Side
O=
2
24
H=
Total Number of Atoms
H+2 + O2
Subscripts and Coefficients
• When balancing chemical equations, it is important to note
that the subscripts can never change
• For example, in the equation below, the subscript of 4 in
methane cannot be changed, neither can the subscripts 2 in
Oxygen, Carbon dioxide and Water
CH4 + 2 O2
CO2 + 2H2O
• Only coefficients can be added by putting whole numbers in
front of the compounds when balancing chemical reactions
How Do we Balance Chemical Equations?
• By placing coefficients in front of each molecule
or compound
• Subscripts cannot be changed!
• Ex: CH4 + 2O2 CO2 + 2H2O
Balancing Chemical Equations
Remember: When balancing chemical equations, it is important to
note that the subscripts can never change!!!!
2
___O
___O
3
2
3
___
2 Mg + ___ O2
___
2 MgO
Practice:
Determine how many atoms of each element are in
each compound below:
1)
2)
3)
4)
2 Na + ___ Cl
___
2
4 Fe + ___
3 O
___
2
___
4 Al + ___
3 O2
2 Na + ___ F
___
2
2
___
NaCl
2 Fe O
___
2 3
___
2 Al2O3
2 NaF
___
Physical States
• In a reaction, we often use symbols to represent the physical state of
the reactants and products
• Look at the reaction below when sodium metal reacts with water:
Na(s) + H2O(l)
H2(g) + NaOH(aq)
• The symbol (s) tells us that Sodium (Na) is in the solid
state
• The symbol (l) tells us the water (H2O) is in the liquid
state
• The symbol (g) tells us the hydrogen (H2) is in the
gaseous state
• Finally, the symbol (aq) tells us that sodium hydroxide
(NaOH) is aqueous or dissolved in water
Symbol
State
(s)
solid
(l)
(g)
(aq)
liquid
gas
aqueous
What do the symbols represent in a
chemical equation?
• The symbols represent the physical state of the
reactants and products
Symbol
State
solid
Na(s) + H2O(l)
H2(g) + NaOH(aq) (s)
(l)
(g)
(aq)
liquid
gas
aqueous
or dissolved
in water
Summary
(you can always write your own summary)
• Explain the Law of Conservation of Mass in your own words
and apply it to chemical reactions:
• What is the difference between the reactants and products
in a chemical reaction?
• Describe the process of balancing chemical reactions, be
sure to explain how you count atoms on both sides of the
equation
• What can you not change when balancing chemical
reactions?
• Is the reaction below balanced? Explain why or why not:
K + Cl2 KCl