Transcript Document 7739552

Have you ever heard the word
bonding before?
If so, where did you hear it and what
does it mean?
If you have never heard it
before write down what you
think it means?
Bonding is what keeps
elements and ions of
compounds together!!!
What’s the difference between
an Element and a Compound?
Give an example of each and
explain why.
Elements
An element is a substance that cannot
be broken down into different
substances.
It is the smallest form of matter that
has the same characteristics of that
substance.
Examples: Au (gold), Na (sodium) etc.
COMPOUNDS
Define what a compound is?
Two or more DIFFERENT atoms
(elements) that are chemically bonded
together because of a chemical
reaction. CH COOH + NaHCO ===> CH COONa + H O + CO
We use chemical formulas to
represent compounds. Can you think
of any…?
H2O (Wudder) CO2 (Carbon Dioxide)
3
3
3
2
2
1
2
D Mixture of
A Element
Compounds
4
3
5
A Elements
B Compounds
6
E Mix of
Elements/
Compounds
C Mix of
Elements
A New
Language
Let’s do the Vial Lab!
We will talk about
4 TYPES OF BONDS
IONIC (Ions)
(Sharing
COVALENT valence electrons)
(Metals)
METALLIC
(Ions)
HYDROGEN
IONIC BONDS
• Form between ions
with opposite
charges: + and -. (a
metal and a nonmetal)
• They bond because
the opposite charges
are attracted to
each other. (Think
magnets!!!)
IONIC BONDS
Like charges repel
each other!
Ions and ionic bonds
form because
electrons are
transferred from
one atom to the
other
Properties of
IONIC BONDS
• Ionic compounds have high melting and
boiling points.
• These are very strong bonds.
• An example is Na+1 + Cl-1
= NaCl (salt)
NaCl Melting point 801 °C NaCl Boiling point1465 °C
IONIC BONDS
Only certain ratios (combinations) of elements
result in the formation of Ionic compounds.
For ex: Lithium (Li) will react with Fluorine (F)
to form LiF.
BUT, it will NOT form LiF2, LiF3, etc.
Magnesium (Mg) will react with Fluorine to form
MgF2.
BUT, it will NOT form MgF, MgF3, etc.
IONIC BONDS
• When writing a chemical formula for an
ionic compound:
*The charges have to balance
to create a neutral compound.*
IONIC BONDS
• For example:
- With salt the charges are
both 1: Na+1 and Cl-1
So we just need one of each ion to make
the compound neutral
= the ratio is 1:1
= NaCl
IONIC BONDS
• What if the charges are not the same
number???
- Like Li+1 + O-2
Here you will not have a 1:1 ratio. You
need to balance the chemical formula…
IONIC BONDS
• What could you do to get the charges to
cancel out if you wanted to form this
ionic compound???
Li+1 + O-2
ANSWER: You would need to use
2 Li+1 for every O-2!!!
= Li2O
IONIC BONDS
Let’s Practice!!! Write chemical formulas for:
1.) K and N
2.) Ca and F
3.) Li and Cl
4.) Mg and Si
5.) Al and O
1.) K3N
2.) CaF2
3.) LiCl
4.) Mg2Si
5.) Al2O3
IONIC BONDS
How did you do???
6.) Ca and Cl
7.) K and P
8.) Mg and Cl
9.) Li and P
10.) K and O
6.)
7.)
8.)
9.)
10.)
CaCl2
K3P
MgCl2
Li3P
K2O
Rb
Chemical Formulas
and Cl
Na and S Li and P
1. Hints: The metal comes first, the non-metal comes second
Change the end of the name of the second element to “ide”
Copy down this table for your answers.
Metal Nonmetal Chemical
Formula
Compound Name
2. If you mix Calcium Chloride (CaCl2) into a glass of water
until it dissolves, what is the chemical formula?
Chemical Formulas
Rb
and Cl
Na and S Li and P
1. Hints: The metal comes first, the non-metal comes second
Change the end of the name of the second element to “ide”
Metal Nonmetal Chemical
Formula
Rb
+1
Cl
-1
Na +1
S
-2
Li
P
-3
+1
Compound Name
RbCl
Rubidium Chloride
Na2S
Sodium Sulfide
Li3P
Lithium Phosphide
2. If you mix Calcium Chloride (CaCl2) into a
glass of water until it dissolves, what is the
chemical formula?
CaCl2 (aq)
Ionic Bonds Warm-up
Write the chemical formulas for the compounds
formed when these ions bond:
11.) Al & S
11.) Al2S3
12.) Rb & O
12.) Rb2O
13.) Be & F
13.) BeF2
14.) Al & Cl
14.) AlCl3
15.) Ca & N
15.) Ca3N2
16.) Ga & Se
16.) Ga2Se3
Questions
Without using your notes, answer the following questions.
Write the questions!
1. What is a compound?
Two or more DIFFERENT atoms (elements) that are
chemically bonded together because of a chemical
reaction.
2. Which formula is a compound and why?
C8H10N4O2 or F2
C8H10N4O2= compound
3. What are the element(s) that make up each chemical
formula in question 2? How many are in each element?
8 Carbon, 10 Hydrogen, 4 Nitrogen, 2 Oxygen
2 Fluorine
COVALENT BONDS
• Form between two
non-metals
• They bond because the
outer electron rings
are not full so they
share valence
electrons!
• (The atoms are NOT
stable.)
Properties of
COVALENT BONDS
• Covalent compounds will have low melting
and boiling points.
• These are usually weak bonds.
• Some examples are H2O (water/ wudder),
and CO2 (Carbon Dioxide)
COVALENT BONDS
• The reason H2O is covalent:
Remember H can be a metal or a nonmetal!!! (See RFA 11)
Here H is behaving like a non-metal.
Hydrogen is usually a non-metal!
Let’s Practice!
Write the following compounds and
determine if they are Ionic or Covalent?
1.) NH3
2.) NaCl
3.) CH4
4.) CO2
5.) CaCl2
6.) KBr
7.) AlCl3
8.) P2O5
9.) Li3P
10.) BN
11.) N2O
12.) MgS
ANSWERS…
1.) NH3 Covalent
7.) AlCl3 Ionic
2.) NaCl Ionic
8.) P2O5 Covalent
3.) CH4 Covalent
9.) Li3P Ionic
4.) CO2 Covalent
10.) BN Covalent
5.) CaCl2 Ionic
11.) N2O Covalent
6.) KBr Ionic
12.) MgS Ionic
Lewis Structures
Electron Dot Diagrams
• We can show how the atoms share or
transfer electrons by drawing electron
dot diagrams.
• You will only use the valence e- for
dot diagrams.
Dot Diagrams
• Start the dot diagram by writing the
atomic symbol for the atom.
Ex: Mg
The symbol has 4 sides…
Dot Diagrams
Mg
Each side can hold up to 2eYou cannot pair the electrons until
there is one on each side.
Dot Diagrams
Mg
Mg only has 2 valence e-.
So it’s dot diagram looks like this:
Mg
Let’s try…
Si
how about…
S
Dot Diagrams Practice!!!
Draw the Dot Diagrams for:
1.)
Cl
2.)
Al
3.)
Na
4.)
Sn
5.)
Ar
Dot Diagrams
Now we can put individual diagrams
together to show whether atoms
transfer or share their valence e-!!!
Who donates their electrons,
metals or non-metals?
Metals always donate their electrons!
Dot Diagrams for Ionic Bonds
In an Ionic Bond, atoms are transferring
their valence e- …
To show this “transferring” , we draw
arrows between the Atomic Symbols to
represent the transferring of e-.
We can show this w/ dot diagrams.
For Ex: (Li + Cl = LiCl)
Cl
Li
Dot Diagram Practice for
Ionic Bonds
1. BeO
2. NaCl
3. MgS
4. CaCl2
5. LiP
6. AlCl
Dot Diagram Practice for
Ionic Bonds
2.
NaCl
3.
MgS
Dot Diagram Practice for
Ionic Bonds
5.
LiP
6.
AlCl
Dot Diagrams for Covalent Bonds
In a Covalent Bond, atoms are sharing their
valence e- …
To show this “sharing”, we draw a BAR
between the Atomic Symbols to represent
the sharing of e-.
One bar = 2 e-.
For Ex: H2O
Dot Diagrams for Covalent Bonds
One bar = 2 e-.
For Ex: H2O (draw out the individual dot
diagrams first.)
H
O
H
***H’s ALWAYS have to go on the ENDS.
Dot Diagram Practice for
Covalent Bonds
1. CO
2. CH
3. SO
4. NH
5. SiO
6. CF
Bonding Dot Diagram Steps
1.) Identify the type of bond you have.
(Covalent or Ionic)
2.) Separate the individual elements and put
them in a line. Put the atomic symbol w/ least
amount of valance electrons in CENTER!!!
3.) Except the Hydrogen’s!!!! Remember H’s
have to be on ENDS!!!
4.) Draw the “dots” for each atomic symbol.
Bonding Dot Diagram Steps
5.) Show either the transferring or
sharing of e- with arrows or bars.
6.) If sharing (covalent bonds)…connect
the “lonely” dots between DIFFERENT
symbols!!!
7.) Count the e- around each atomic
symbol to make sure there are 8!!!
(ONLY 2 for H!)
1234 HONC
Based on your prior knowledge of atoms and their
valance electrons, what in the world does
1234 HONC mean?
Hydrogen, Oxygen, Nitrogen, Carbon
Based on their valance electrons, how many atoms
can bond to each of them?
1 2 3 4
H O N C
H= can form one bond.
O= can form two bonds.
N= can form three bonds.
C= can form four bonds.
**This works for COVALENT bonds only**
Dot Diagram Practice
1.) NF3
2.) Sr3N2
Dot Diagram Practice
1.) NF3
2.) Sr3N2
3.) Rb2O
4.) CH3Cl
5.) Al2S3
6.) Na3N
Dot Diagram Practice
3.) Rb2O
4.) CH3Cl
Dot Diagram Practice
5.) Al2S3
6.) Na3N
Dot Diagram Practice
7.) CH3Br
8.) NH2Cl
9.) PCl3
10.) CH4
11.) Br2O
12. IBr
Dot Diagram Practice
7.) CH3Br
8.) NH2Cl
Dot Diagram Practice
9.) PCl3
10.) CH4
Dot Diagram Practice
11.) Br2O
12. IBr
Quick Quiz
Covalent bonds form because…
A.
B.
C.
D.
E.
Share valence electrons
Like charges attract
They gain neutrons
Opposite charges attract
They share protons
The compound C6H12O6 has
A.
B.
C.
D.
E.
Ionic bonds
Covalent bonds
Nuclear bonds
Metallic bonds
Hydrogen bonds
Covalent bonds mostly occur with
atoms on the right side of the
periodic table.
A. True
B. False
Ionic bonds have…
A.
B.
C.
D.
Strong bonds, low boiling
and melting points
Weak bonds, low boiling
and melting points
Strong bonds, high boiling
and melting points
Weak bonds, low boiling
points and high melting
points
Ionic bonds are formed because
A.
B.
C.
D.
E.
F.
Opposite charges attract
Share valence electrons
Electrons are transferred
Protons are transferred
Both A & C
Both C & D
Which compound has ionic
bonds? *
A.
B.
C.
D.
CO2
CuSO4
O2
CH4
The Law of Conservation
of Mass
The Law of Conservation of Mass
states that in a chemical reaction, mass
cannot be created or destroyed, but it
can change forms!
So this means that the mass before the
reaction has to be the same as the mass
after the reaction.
Does this equation go against the
Law of Conservation of Mass?
(count the atoms of each element)
Photosynthesis
6CO2 + 6H2O
Reactants
Chemical
Reaction
C6H12O6 + 6O2
Products
Balancing Equations
Due to the Law of Conservation of Mass each
type of element needs the same amount before
the reaction and after the reaction.
“reactant(s) = product(s)”
But, you can’t change the elements that
participate in the reaction, so you must write a
number in front of (to the left of) each material
in the reaction to make sure every type of
element has the same number on each side of
the reaction.
How molecules are
symbolized
Cl2
Cl
2Cl
Cl
Cl
Cl
2Cl2
Cl
Cl
Cl
How is the middle picture
different from the other two?
Cl
Balancing Equations
CaCl2  Subscript
The little two tells you that there are 2 Cl. It only
applies to the Cl.
But… 2CaCl2
When you have a Coefficient 2CaCl2
CaCl2
+CaCl2
The 2 tells you that there are 2Ca and 4Cl
It applies to everything behind it in the compound.
You will NEVER add a subscript
only Coefficients!
Understanding
Chemical Compounds
How many atoms are in each chemical compound?
C6H12O6
2H2O2
6CuNO3
6 C
4 H
12 H
4 O
6 O
6 Cu
6 N
18 O
Now, Does this equation go against
the Law of Conservation of Mass?
6CO2 + 6H2O
C6H12O6 + 6O2
6C
6C
12 O
12 H
12 H
6 O
6 O
12 O
This does not violate the Law of Conservation of Mass
Understanding Chemical Compounds
How many atoms are in each chemical compound?
C20H30O2
20 C
3C6H12S2
18 C
6 K
2K3PO4
2C3H7NO2 6 C
4 Al
2Al2S3
4 K
4KClO3
30 H
36 H
2 O
6 S
2 P
8 O
14 H
6 S
2 N
4 Cl
12 O
4 O
Try this without using your notes
Explain what are three differences between
a Covalent bond and an Ionic Bond?
Covalent Bonds
Ionic Bonds
1. Share valence electrons
2. Non-metal and Non-metal
3. Weak bonds
4. Low Boiling Pts. and
Melting pts.
1. Opposite charges attract
2. Metal and Non-metal
3. Strong bonds
4. High Boiling Pts. and
Melting pts.
RFA 23
CaCl2
C6H12O6
H2SO4
NH4Cl
2NH4NO3
3BaTiO3
Ca
2 Cl
6 C
12 H
6 O
2 H
S
N
4 H
Cl
2 N
8 H
2 N
3 Ba
3 Ti
9 0
4 O
6 O
4NaHCO3
4 Na
4 H
8Bi2Te3
16 Bi
24 Te
5CaCrO4
5 Ca
5 Cr
20 0
3SiH2Cl2
3 Si
6 H
6 Cl
6Fe2O3
12 Fe
18 O
5NaOH
5 Na
5 O
4 C
5 H
12 O
Warm up Review
What is the chemical formula for
each one and WHY?
Na Na
Na Na
1.) Na Na
2.)
3.)
Na Na
Na
Na
1.) 3Na2 (3 pairs chemically bonded)
2.) Na2 (1 pair chemically bonded)
3.) 2Na (not chemically bonded)
Balancing Equations
What’s the difference between…
A2 + B2 and A2B2 ?
A2 + B2 = Not chemically bonded, so its
not a compound! These are elements.
A2B2 = This is chemically bonded because
it is a compound.
Balancing Equations
Let’s look at an example:
Element Mg will bond with element O in
the chemical reaction below:
Mg + O2
MgO
Mg + O O
 Mg O
Are there the same amount of O’s on the
left as there are on the right???
NO!!! We must balance this equation!!!
Balancing Equations
How can we make there be the same # of each
element on both sides???
Mg + O2
Mg + O O
“reactants

MgO
 Mg O
= product”
By putting a coefficient in FRONT...
Mg + O2  2MgO
You multiply all of the elements in the compound by
the coefficient in front.
Is it balanced yet???
NO!
Balancing Equations
Where else could we put a coefficient to balance it?
Mg + O2  2MgO
“reactants = product”
We need to add a coefficient in the front on the
other side…
2Mg + O2  2MgO
“reactants = product”
There are 2Mg’s and 2 O’s on the left AND there
are 2Mg’s and 2 O’s on the right…NOW it’s
BALANCED!!! 
Balancing Equations
2Mg + O2  2MgO
Reactants = product
I only added Coefficients!
So let’s practice with some real
problems to see how you do!
1.)
2.)
3.)
3.)
4.)
4.)
5.)
5.)
Balancing Equations
Let’s practice…
Al + Br2
H2 + O2
Na + Cl2
2Na + Cl2
Fe + O2
4Fe + 3O2
P4 + O2
P4 + 5O2
AlBr3
H2O
NaCl
2NaCl
Fe2O3
2Fe2O3
P2O5
2P2O5
Balancing Equations…
6.) N2 + H2
7.) Mg + O2
8.) H2 + Cl2
9.) Ag + S
10.) S + O2
NH3
MgO
HCl
Ag2S
SO4
Balancing Equations…
Lets see how you did!
6.) N2 + 3H2
2NH3
6a.) 2N2 + 6H2
4NH3
7.) 2Mg + O2
2MgO
8.) H2 + Cl2
2HCl
9.) 2Ag + S
Ag2S
10.) S + 2O2
SO4
Is this balanced?
Metallic Bonds
• Form between 2 metal atoms. (metal and metal)
• The atoms are unstable – they do not have full
electron rings.
• Bond by sharing very loosely held valence
electrons with each other. (The electrons “flow”
between the atoms.)
• Metallic bonds are NOT the strongest bonds
though…
• Ionic Bonds are the strongest bonds!
Properties of
Metallic Bonds
• Metallic compounds are highly
conductive. (They conduct heat &
electricity very easily!!!)
• They also have metallic luster (shine)
• They are malleable (able to be
hammered into thin sheets.)
• They are ductile (can be rolled into
wires.)
• Examples: CuZn, AlSb, GaSb, LaMg
What makes it easier for some atoms
to bond better than other atoms?
When you think about atoms bonding,
what do atoms need to gain or lose?
VALENCE ELECTRONS!!!
N-3
Li+1
Which atom will bond the easiest?
Li+1 Why?
The LESS electrons an atom needs to
gain or lose to have a full outer ring, the
EASIER it is for that atom to bond!!!
Which groups (1-18) on the periodic
table, will bond the easiest?
Which groups on the periodic table will
share or transfer electrons the easiest?
(i.e. be most likely to form bonds?)
ANSWER: Groups 1 and 17 b/c group 1
only needs to get rid of 1e- and group
17 only needs to gain 1e-.
Question…
Is an element in Group 13 more likely to
bond than an element in Group 16?
EXPLAIN…
ANSWER: No, b/c the element in Group
16 only needs to gain 2e-, but the
element in Group 13 needs to lose 3e-.