Transcript 2 - Rock Hill High School

FLASHBACK
• How many electrons do all atoms want in
their outer shell?
• How do these atoms get those e-’s in the
outer shell?
• How can you tell how many valence e-’s an
atom has?
• If atoms gain e-’s, they become ____________
charged.
• If atoms lose e-’s, they become ____________
charged.
Unit 4
Ch.
20/21
To increase stability of the atoms
Group 1 and 2 metals transfer electrons to Group
16 and 17 nonmetals to create ionic bonds.
Metals lose electrons &
nonmetals gain electrons to
achieve noble gas structure!
-1
-1
Cl
Cl
CaCl2
+2
Ca
Calcium ion will give up its outer electrons to both
chlorine atoms
Br
Br
+2
Mg
MgBr2
H2O
H
O
H
Oxygen only needs two
electrons so hydrogen
shares its one valence
electron so that both
atoms fill their outer
shells.
Weaker bonds form
Ionic vs.
Covalent
Video
Shows only
valence
electrons of
atom with
dots around
the element's
symbol
What’s the
point?
P=1
N=0
P=20
N=20
1 e-
H
2 e- 8 e- 8 e-
2 e-
Ca
Nitrogen:
Strontium:
Water: H2O
N
Sr
FLASHBACK
1. What types of elements occupy space in
groups 1 and 2?
2. How many valence e-’s do these groups have,
respectively?
3. What will their ionic charges be, respectively,
if they lose their valence e-’s?
4. Metals will _____________ e-’s.
5. Non-metals will ________________ e-’s.
6. What e-’s do the bonding?
7. Explain difference between ionic and
covalent bonds.
Bonding Worksheet:
5. Cl
4. Na
7. Be
11.
10. Ne
Mg
Covalent or ionic bond?
12. HCl_________________________
14. AlO3________________________
Using electron dot diagrams, draw the ionic bonds…
17. NaCl
Ionic vs. covalent...
Which will win???
Investigating the difference
between sugar and salt!
Sugar!
Salt!
Who knew Chemical Bonding
could be so cool????
Want to give it a try???
Extra Credit by the end of the 9 weeks
th
(March 23 ) for a Chemistry Rap
Video!
Covalent Structures: make
molecules and SHARE ELECTRONS
Example: H20, CO2, C12H22O11
same charges, so no strong attraction
Ionic Structures: make ionic
crystals and TRANSFER ELECTRONS
Example: NaCl, KI, CaF2
+ and – charges make a STRONG
attraction!
A. When positive and negative ions surround each other,
they form tightly packed structures called ionic crystals or
crystal lattices
Substances with network (ionic) structures are usually strong solids
with high melting and boiling points
Substances made of molecules have lower melting and boiling
points
What happens if it is not the neutral element..
But the ion??
e- diagram
Na
Cl
Mg
lose or gain e-?
new (ion) e- diagram
SECTION 1 REVIEW
Pg. 606 # 4, 5
CHAPTER REVIEW
Pg. 626 # 4-6, 11, 14, 17, 18
1. Which of the substances has the lower
melting point (which melted faster)? Was this
what you expected? Why or why not?
2. Relate your results to ionic and covalent
bonding.
3. On a molecular level, how do the bonds in
sugar and salt differ?
4. Why do atoms bond?
5. Water (H2O) contains a(n)
_________________ bond.
Calcium oxide (CaO) contains a(n)
________________ bond.
FLASHBACK
EOC WORKBOOK!!!
Pg. 38 (all)
Pg. 39 (all)
Pg. 36 (all)
Pg. 37 (all)
FLASHBACK
1. Table salt (NaCl) has what kind of bond?
2. Table sugar (sucrose, C12H22O11) has what
kind of bond?
3. When heated, what happened to the bonds in
sugar?
4. When heated, what happened to the bonds in
salt?
5. Provide the electron dot structure for Barium
(Ba), Iodine (I), and Cesium (Cs).
Review of Terms!
1. Cation: positively charged ion
- Non metals or metals?
2. Anion: negatively charged ion
- Non metals or metals?
1. Symbol: element being used
2. Subscript: shows how many of the individual
atoms are present
ex.
O2
CO2
HBr
3. Coefficient Number: placed before the element or
compound, distributed to entire compound
ex. 2HBr
or
2H2 + O2  2H2O
4. Oxidation Number: same as “charge”, how many
electrons atoms need to gain or lose (to become stable)
**get off of periodic table!!
**write them on your P.T. (Al = +3)
The chemical symbols and numbers
indicating the number of atoms
contained in the basic unit of a
substance
C6H12O6
Carbon = 6 atoms
Hydrogen = 12 atoms
Oxygen = 6 atoms
How many atoms of each element are
present in 3 molecules of glucose?
3 C6H12O6
C=18
H=36
O=18
The elements overall charges have to equal
zero
Compounds have no net charge!!
Write the cation first with its charge, then
the anion and its charge.
Al+3 F-1
Write the chemical formula, using subscripts
to indicate how many of each ion are
needed to make a neutral compound.
criss-cross method: Al+3 F-1 = AlF3
 Balance the formula so the compound
formed has a neutral charge
Examples:
 Ca+2
+
Br –1
 Na+1 + S –2
 Al +3 + Cl-1
Ionic compounds are formed by the strong attractions
between cations and anions. Both ions are important
to the compound’s structure, so it makes sense that
both ions are included in the name
1. Name cation first (metal)
2. Name anion (nonmetal)
3. Drop the end of the anion & add suffix
–ide
EXAMPLE: NaCl = sodium chloride
cation
anion
Cs+1,cesium
F-1,fluorine
Ba+2, barium
Cl-1,chlorine
Al+3, aluminum
S-2, sulfur
Balance Compound
formula
name
CsF
Cesium
Fluoride
BaCl2
Barium
chloride
Al2S3
Aluminum
sulfide
 Uses prefixes!!!!
If there is only one atom of
the first element, it does not
get a prefix
EX: BF3= boron trifluoride
Dihydrogen monoxide =
????
Number of
atoms
1
2
3
4
5
6
7
8
9
10
prefix
MonoDiTriTetraPentaHexaHeptaOctaNonaDeca-
Dihydrogen Monoxide!!!!!!!!
Why????
If H20 is water, what
is H204?
Drinking, bathing,
washing,
swimming…
All kinds of things!
What’s in a name???
How many people can you “bond” with!? 
You must turn in to me a piece of paper with…
1.Your element and it’s oxidation number
2.A total of 6 IONIC COMPOUND formulas
3.AND the name of those compounds
My Ion
What I am
bonding with
Chemical
Formula
Name
Fe+2
O-2
FeO
Iron Oxide
Try these covalent molecules…





CO
CO2
N5H8
TeBr2
Si3S7
Carbon monoxide
Carbon dioxide
Pentanitrogen octahydride
Tellurium dibromide
Trisilicon heptasulfide
FLASHBACK
1. How many oxygen atoms are there in bleach,
NaClO, AKA sodium hypochlorite?
2. Acetone (CH3COCH3), or nail polish remover,
has how many total hydrogen atoms?
3. How do you determine oxidation #’s?
4. What is the oxidation # of Al, O, & Cl ?
5. Write ionic formulas: (find charges 1st then criss-cross!!)
Mg + F
Be + N
6. Name the following compounds:
N5H8
SrCl2
COVALENT:
NO
NO2
N2O
IONIC:
NaF
ZnCl
CaCl2
1. Electron Dot Diagram:
Hydrogen: H
2. Pictorial Diagrams:
H
Oxygen:
O
Water: H2O
H
O
H
Covalent
bonds!
Chemical
Changes
and
Chemical
Reactions
Occur when the size or shape of the substance is
changed
Occasionally, the color can change, too
Regardless, the original substance(s) do not change
Evidences of Physical Changes:
- Bending, stretching, heat, and cooling can all cause a
physical change
***All phase changes are physical changes
Occurs when there is a change in the
arrangement of atoms so that a different
substance with different properties is
produced
Very often,
there is some
kind of
evidence
(for example,
the formation
of a gas)
1. Formation of a gas
2. Reaction with acids
(like this picture of copper
reacting with nitric acid)
3. (Sometimes) a color
change can indicate a
chemical change.
- A good example of this
is metal tarnishing
Is a neutralization reaction a
chemical change?
1. Bubbles/fizzing/formation
of a gas
2. Precipitate formed
3. Energy change
4. Color change
5. Odor…
Chemistry Joke!
If you're not part of the
solution…
You're part of the
precipitate!
FLASHBACK
1. What is the main difference between a
chemical and physical change?
2. If a reaction forms a gas, you know it is a
______________ change.
3. If something changes color, you know it’s a
chemical change.
True
False
4. Name the four evidences of a chemical rxn.
5. Explain a situation in which bubbling occurs,
but it is NOT a chemical change.
Why do you burp after drinking a Coke?
Excuse me…
• Coke and other soft drinks are carbonated
• Carbonation occurs when carbon dioxide is
dissolved in water or solution
• This gives the "fizz" to carbonated beverages
• Excess gas needs out of the stomach.. So we
burp!
Using the materials provided:
1. 2 pieces of Alka-Seltzer
2. 1 film canister
3. Water
…you are to
build a projectile!
Pick ONE question to answer and generate a
hypothesis and WRITE IT DOWN…
Use an “If-Then” statement!
1. How does changing the volume of water
effect the time/height of rocket “launch”?
2. How does changing the amount of AlkaSeltzer effect the time/height of rocket
“launch”?
Lab Report
You are to write a brief lab report on your experience…
- Skip lines between headings
- Full sentences!
Alka seltzer
Title
Hypothesis: (your question)
Data: Table? List?
Conclusion: tell me what you learned (in paragraph form!)
1. What evidence did you see of a chemical reaction
taking place? How does this relate to the lab?
2. Refer back to your hypothesis… was it right or
wrong??
Why??
3. What would have done differently… or how would
you make this lab better?
FLASHBACK
EOC WORKBOOK
Pg. 41 (all)
A. An exothermic reaction __________________ heat.
B. An endothermic reaction __________________
heat.
C. ( A + B  AB ) is an example of a _____________
reaction
Naming:
2) P2O5 ___________________________
3) Mg3N ___________________________
5) SiO2 ____________________________
6) BaCl2 _______________________________
8) B2P9 _____________________________________
Formulas:
14) aluminum nitride ____________________
16) disulfur pentaphosphide ____________________
17) potassium sulfide __________________________
18) rubidium iodide ____________________________
20) hexacarbon dichloride ______________________
Chemical Reactions and
Equations:
What do they mean?
What do they show?
During any chemical reaction, there is an
energy change.
1. Exothermic reaction: heat is released during
the reaction, gets hot!
2. Endothermic reaction: heat is
absorbed during the reaction,
gets cold!
Everyday Exothermic and Endothermic
Reactions
•AIRBAGS!
Instant
Cold
Packs
The airbag's inflation system reacts
sodium azide (NaN3) with potassium
nitrate (KNO3) to produce nitrogen gas.
Hot blasts of the nitrogen inflate the
airbag.
Instant
heat
packs
Exothermic vs. Endothermic
Endothermic Reaction
A. Reactants: original substances entering a
chemical rxn
- what you started with, on the left side
B. Products: resulting substances
- what you end with, on the right side
Reactants  Products
Endothermic vs. Exothermic
Calcium Chloride vs. Sodium
Bicarbonate…
who will win the temperature war???
Turn into me:
Half sheet of paper
1. Synthesis: 2 substances combine to form 1
substance
A + B -> AB
2. Decomposition: 1 substance breaks down
(decomposes) to 2 substances
AB -> A + B
(opposite of synthesis)
3. Single Displacement: 1 element replaces another
A + BC -> AC + B
4. Double Displacement: positive ion of one
compound replaces positive ion of another
AB + CD -> AD + CB
1. 4Al + 3O2 --> 2Al2O3
Synthesis
2. Ca(OH)2 --> CaO + H2O
Decomposition
3. Zn + CuSO4 --> ZnSO4 + Cu Single Displacement
4. Cl2 + 2KBr --> 2KCl + Br2 Single Displacement
Double
5. BaCl2 + Na2SO4 --> 2NaCl + BaSO4
Displacement
6. 2H2 + O2 --> 2H2O
Synthesis
FLASHBACK
Label the following equations: (4types)
1. Zn + HCl  ZnCl2 + H2 Single Displacement
2. Fe + O2  Fe2O3
Synthesis
3. SiO2 + HF  SiF4 + H2ODouble Displacement
4. FeS + HCl  H2S + FeCl2Double Displacement
5. In lab yesterday, what gas produced the
signature “popping” sound?
You will be conducting reactions to produce 5 different common gases
and observe their chemical and physical properties.
CO2
A. NaHCO3 + HCl  NaCl + H20 + ______
B. Cu + 4HNO3  Cu(NO3)2 + 2H20 + 2NO
_____
2
NH
3
C. NH4Cl + NaOH  NaCl + H20 + ______
2
D. 2H2O2  2H2O +O____
2
E. Mg + 2HCl  MgCl2 + H
____
FLASHBACK
Section Review
Pg. 645 #1, 3
EOC REVIEW
Pg. 656 #1-5, 11, 15
FLASHBACK
EOC WORKBOOK
Pg. 43 [all]
Chemical reaction - is the process of
changing reactants to products by a
chemical change
Chemical reactions are symbolized by
Reactants Products
(s) solid; (l) liquid; (g) gas; (aq) aqueous
are the physical states of the reactants and
products
 The reactants which enter into a reaction.
 The products which are formed by the
reaction.
 The amounts of each substance used and each
substance produced.
___Mg
2
(s) + __ O2(g)

__
2 MgO(s)
 We use subscripts to balance compounds
 CaCl2
 subscripts cannot be changed
 We use coefficients to balance equations
 2 NaCl + _ Ca(OH)2  2 NaOH + __ CaCl2
Goal: to get the same number of
atoms on both sides of the equation
__ Al + __ O2  ___ Al2O3
__ NaCl  __ Na + __ Cl2
__ Li + __ H2O  __ LiOH + __ H2
A. A balanced chemical equation represents
the process of a chemical reaction in
which atoms are rearranged but not
created or destroyed.
B. By balancing chemical equations, you
show that mass is conserved…
Law of Conservation of Mass!
Mass is neither created nor
destroyed in an ordinary chemical
or physical reaction
Mass of Reactants
=
Mass of Products
LAB:
Looking at the…
Law of Conservation
of mass!!!
FLASHBACK
Balance the following equations:
1. ___Zn + ___HCl  ___ZnCl2 + ___H2
2. ___Fe + ___O2  ___Fe2O3
3. ___SiO2 + ___HF  ___SiF4 + ___H2O
4. ___FeS + ___HCl  ___H2S + ___FeCl2
5.What is the overall goal of balancing
equations?
FLASHBACK
Balance the following equations:
1. __S8 + __O2

__SO2
2. __ HgO  __Hg + __ O2
3. __BeCl2 + __KOH  __Be(OH)2 +__KCl
4. __S8 + __ O2  __ SO3
5. __H3PO4 + __Mg(OH)2 __Mg3(PO4)2 + __H2O
Reaction Rates!
Reactions occur when
particles of reactants
collide with energy
1. Temperature: higher temperature,
reaction rate increases
1. Particles moving faster, more collision
between particles
2. Concentration: when reactants are
more concentrated, rate of reaction
increases
1. More particles mean more collisions
3. Surface Area: more surface
area, reaction rate increases
4. Catalyst: presence of catalyst
speeds up reaction without
being permanently changed
[Inhibitor: slows down a reaction]
Video!
EOC WORKBOOK
Pg. 45 [# 2-6]
Pg. 46 [# 1-6]
Make some observations of salt under
a microscope!!
http://www.sciencenetlinks.com/lessons.php?Benchm
arkID=4&DocID=173
http://www.sciencenetlinks.com/lessons.php?Benchm
arkID=4&DocID=173
http://www.mos.org/sln/sem/sem.html