1
2
GOALS
1. Compare & contrast ionic and covalent bonds in terms of
electron position.
2. Predict formulas for stable binary ionic compounds
based on balance of charges.
3. Use IUPAC nomenclature for transition between chemical
names and chemical formulas of
- binary ionic compounds
- binary covalent compounds
4. Apply the Law of Conservation of Matter by balancing
the following types of
chemical equations:
• Synthesis
• Decomposition
34
16
• Single Replacement
• Double Replacement
3
Why do Atoms Form Compounds?
• Stability.
• What makes an atom stable?
• Full outer energy level.
• Eight.
• Chart page 576.
4
• A Chemical Bond holds atoms
together in a compound.
• Two basic types:
•Ionic
•Covalent
5
Ionic Bonding
Remember: Atoms need a full outer energy level
to be stable.
EIGHT!
6
7
8
OPPOSITES ATTRACT!
9
10
Covalent Bonding
11
12
Hydrogen and Fluorine
Hydrogen and Chlorine
13
Single, Double, Triple
14
Clip
15
Unequal Sharing
δ+
Polar
δ_
When one
atom has a
greater
positive
charge
16
1. CO2
2. H2O
3. NaCl
4. MgCl2
5. NO2
6. H2SO4
7. NaF
clip
9. NaPO4
10.HCl
11.NaF
12.KCl
13.CaCO3
14.N2
15.Cl2
Goals
revisited
17
•Writing chemical formulas is a shorthand way of
indicating what a substance is made of.
•These formulas also let you know how many atoms
of each type are found in a molecule.
The chemical formula for water is H2O.
Carbon Dioxide is CO2.
Why does oxygen combine in different ratios,
in different compounds?
The chemical formula for table salt is NaCl.
Calcium Chloride is CaCl2.
Why does chlorine combine in different
ratios, in different compounds?
18
The simplest compounds
are ones with only two
elements
These are called binary
KI, CO, H2O, NaCl
+1
+4
-4
Oxidation numbers
0
Tell you how many electrons an
atom must gain, lose or share to
become stable.
+2
19
+3
-3
-2
-1
20
Oxidation numbers
+1
-1
Cl
We can predict the ratio
of atoms in ionic
valence
compounds based on 1electron
K
their oxidation numbers
All compounds
are
neutral
Tells you how many
electrons an atom
must gain, lose or
share to become
stable.
KCl
7 valence
electron
+1
-1
Br
Na
NaBr
21
+2
Ca
-1
Br
To make it
ZERO, you need
CaBr
1 Ca & 22Br.
Subscripts show the number of atoms of
that kind in the compound
Some elements have more than one
oxidation number (Chart p588)
+3
-2
+2
-2
Fe
O
Fe
O
Fe2O3
FeO
We call these elements- Multivalent Elements
22
1.
2.
3.
4.
5.
6.
7.
Now You Try writing Binary Ionic
formulas
K + Br
8. Ga + Br
Mg + Cl
9. Fe+2 + O
Ca + I
10.Fe+3 + O
K+O
11.Cu+2 + F
K+I
12.Cr+3 + O
Sr + Br
13.Mg + O
Na + O
14.Al + P
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Polyatomic Ions
Cations:
ammonium, NH4+
Anions:
nitrate, NO3-
Groups of
Covalently
Bonded atoms
that stay
together.
sulfate, SO42hydroxide, OHphosphate, PO43carbonate, CO32chlorate, ClO3permanganate, MnO4chromate, CrO42-
25
Try these…….
1.Na + SO4
2.Mg + PO4
3.Ca + CO3
4.Na + OH
5.Mg + OH
6.NH4 + OH
7.K + PO4
8.NH4 + NO3
9.H + SO4
10.Ca + SO4
11.K + NO3
12. Na + PO4
Naming Binary Compounds and
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Molecules
• Steps:
Example:
• NaCl
– If it is Binary1. Decide if it is an ionic or covalent
bond.
– Metal- nonmetal…..
» Ionic
– Nonmetal- nonmetal….
» Covalent
If ionic …….
2. Check to see if any
elements are
multivalent.
3. If all single valent,
write the name of
the positive ion
first.
4. Write the root of
the negative ion
and add –ide.
Examples:
1. NaCl
2.K2O
3.AlCl3
4.BaF2
5.KI
6.Li2O
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If ionic …….
Examples:
2. Check to see if any
elements are multivalent. 1.FeO
3. If multivalent ions,
2.Fe2O3
determine the oxidation
3.CuO
number of the element.
4. Use Roman numerals in
4.Cu2O
parentheses after the
5.PbCl4
name of the element.
5. Write the root of the
6.PbI2
negative ion and add –ide.
31
If Covalent...
2. Use Greek prefix to
Greek Prefixes
indicate how many atoms
1- monoof each element are in
2- dithe molecule
3- tri3. Add -ide to the more
4- tetraelectronegative element
5pentaExample:
6- hexa•NO
7- hepta•Nitrogen Monoxide
•PCl3
8- octa•Phosphorous trichloride
32
If it contains a polyatomic ion...
2. Write the name
Examples:
of the positive
1. NaCO3
ion.
2. KNO3
3. Write the name
of the polyatomic 3. NaC2H3O2
ion.
Example:
•KOH
•Potassium Hydroxide
•CaCO3
•Calcium Carbonate
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Name the following:
1. KBr
2. HCl
3. MgO
4. CaCl
5. H2O
6. NO2
7. CuSO4
8. CaSO4
9. NH4OH
10.CaCO3
11.Cu(ClO3)
12.Cr2O 3
13.SrI 2
14.CCl4
2
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Goals
revisited
35
Chemical Reactions
• A chemical reaction is a change in which one or more substances
are converted into new substances.
– Rearrangement of bonds in compounds and molecules.
• Chemical Equations make it possible to see clearly what is happen
during a chemical reaction
36
Chemical equations are a shorthand way to
show chemical reactions.
Reactants
Products
H2 + O2
H2 O
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Conservation of Mass
38
H2 + O 2
H2O
Does this meet the Conservation of
Mass
Law?
2 Hydrogen
2 Oxygen
atoms
atoms
2 Hydrogen atoms & one
Oxygen atom
Must Balance the Equation to show
Conservation of Mass.
39
Can add coefficients to Balance equations.
2 H2 + O 2
42
Steps:
2 H2O
2
Balanced!!
1. Count Atoms on both sides
2. If not Balanced, add coefficients to balance.
3. Recount atoms after adding each coefficient.
4. Keep adding coefficients until balanced.
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21
40
41
1.Synthesis
2.Decomposition
3.Single Replacement (Single
Displacement)
4.Double Replacement
(Double Displacement)
Synthesis
“to make”
A+B
AB
Cu + O
CuO
2H + O2
2H O
2
2
Decomposition
“to breakdown”
AB
A+B
2H O
2H + O
NaOH
Na+ OH
2
2
2
Single Replacement
When one element replaces another element in a compound
A + BC
AC + B
Cu+AgNO3 Cu(NO3)2+ 2Ag
The more reactive metal will always replace the less
reactive metal. (p749)
Single Replacement
• Clip
Double Replacement
Positive Ion of One compound replaces the positive ion of another
compound and a Precipitate is formed.
AB + CD
AD + CB
Ba(NO3)2+K2SO4 BaSO4 2KNO3
Clip
Clip
51
Chemical Reactions and Energy
• All chemical reactions release or absorb energy.
– Heat, light, sound
• Chemical reactions are the making and breaking or bonds.
1. Exergonic
• Chemical reactions that
releases energy are called
exergonic.
– Glow sticks
• If heat is released, it is
called exothermic.
2. Endergonic
• Chemical reactions that require energy are called endergonic.
• Ex: Cold Packs
• If heat is absorbed, it is called endothermic
Catalysts and Inhibitors
Some reactions proceed slowly.
• They can be sped up by a catalysts.
– Catalysts are not used up in the reaction.
– EX: enzymes (biological catalysts)
Some reactions proceed too fast.
• They can be slowed down by inhibitors.
– EX: Preservatives in food
GOALS Revisited…..
1. Compare & contrast ionic and covalent bonds in terms of
electron position.
2. Predict formulas for stable binary ionic compounds based
on balance of charges.
3. Use IUPAC nomenclature for transition between chemical
names and chemical formulas of
• binary ionic compounds
• binary covalent compounds
4. Apply the Law of Conservation of Matter by balancing the
following types of
chemical equations:
• Synthesis
• Decomposition
• Single Replacement
• Double Replacement