1. Chemical Formulas and Compounds
Oxidation Numbers

2. Monday, November 26
Take out a sheet of paper, title “Oxidation Numbers”
Take out your Naming Compounds sheet that you received before Thanksgiving holiday.
Hall Pass Policy:
2 per NINE WEEKS
Document on Clipboard!

3. Tuesday, November 27 1-15 Compound Naming Problems: Any Questions?
16-30 = Homework Tonight
Must complete entire sheet to retake Quiz 1 &2
Take out OXIDATION NUMBER notes from yesterday
Hall Pass Policy:
2 per NINE WEEKS
Document on Clipboard!

4. Nomenclature QUIZ 1 Ammonium Sulfate Sulfite Arsenate Phosphate
Write the compound name:
CaBr2
CoF3
SnI4
FeS
Ca(OH)2
Write the formula:
Sodium Iodide
Calcium Chloride
Potassium Sulfide
Sodium Carbonate
Calcium Nitrite
Write the nomenclature:
Ammonium
Sulfate
Sulfite
Arsenate
Phosphate
Chlorate
Chlorite
Hydroxide
Tetra-
Penta-

5. Nomenclature QUIZ 2 NaI Carbonate CaO Sulfate K2O NO2 ˉ Ca(OH)2
Write the compound name:
NaI
CaO
K2O
Ca(OH)2
SO3
Write the formula:
Sodium Hydroxide
Lead (II) Nitrate
Nitric Acid
Barium Dioxide
Tricalcium Dinitride
Write the nomenclature:
Carbonate
Sulfate
NO2 ˉ
Nitrate
Phosphate
Hexa-
Nona-
H2SO4
Hydrochloric acid
Nitric Acid

6. Nomenclature QUIZ 3 HNO2 Carbonate HClO3 Ammonium H2SO4 Hydroxide HCl
Write the acid name:
HNO2
HClO3
H2SO4
HCl
H2CO3
Write the formula:
Iron (II) Nitrate
Sodium Fluoride
Carbon Monoxide
Potassium Sulfide
Iron (III) Oxide
Write the nomenclature:
Carbonate
Ammonium
Hydroxide
NO3 ˉ
Perchlorate
Sulfate
Tri-
Octa-
Chlorite
PO4 ³ˉ

7. Oxidation Numbers Oxidation Numbers
the charge that it would have if all the bonds were removed along with the electron pairs that were shared with the central atom.
Use to “keep track” of electrons
In general when assigning oxidation numbers, shared electrons are assumed to “belong” to the more electronegative atom in each bond
Oxidation numbers of carbon and hydrogen in ethane (number does not refer to valance electrons)

8. Oxidation Numbers Assigning Oxidation Numbers
The atoms in a pure element have an oxidation number of zero
Monatomic ions have an oxidation number equal to the charge of the ion
The more-electronegative element in a binary compound is assigned a negative number equal to the charge it would have as an anion. Likewise for the less-electronegative element.
Fluorine has an oxidation number of –1 in all of its compounds because it is the most electronegative element
Oxygen usually has an oxidation number of –2
In peroxides, such as H2O2, oxygen’s oxidation number is –1
In compounds with fluorine, such as OF2, oxygen’s oxidation number is +2

9. Oxidation Numbers Assigning Oxidation Numbers
Hydrogen has an oxidation number of +1 in all compounds containing elements that are more electronegative than it; it has an oxidation number of –1 with metals
The algebraic sum of the oxidation numbers of all atoms in an neutral compound is equal to zero
The algebraic sum of the oxidation numbers of all atoms in a polyatomic ion is equal to the charge of the ion
Although rules 1 through 7 apply to covalently bonded atoms, oxidation numbers can also be applied to atoms in ionic compounds similarly

10. Oxidation Numbers Oxidation Numbers Sample Problem
Assign oxidation numbers to each atom in the following compounds or ions:
UF6
H2SO4

11. Oxidation Numbers Oxidation Numbers Sample Problem Solution
Place known oxidation numbers above the appropriate elements
Multiply known oxidation numbers by the appropriate number of atoms and place the totals underneath the corresponding elements
The sum of the oxidation numbers must equal zero unless there is a charge associated with the compound
+5 2
+5 6

12. Oxidation Numbers
Common Oxidation States of Nonmetals
Pg. 235

13. Oxidation Numbers Oxidation Numbers for Formulas and Names
Many nonmetals can have more than one oxidation number
These numbers can sometimes be used in the same manner as ionic charges to determine formulas (+ -)
What is the formula of a binary compound formed between sulfur and oxygen?
From the +4, +6 oxidation numbers of sulfur, you could predict that sulfur might form SO2 or SO3
Remember: The more-electronegative element in a binary compound is assigned a negative number equal to the charge it would have as an anion. Likewise for the less-electronegative element.

14. Oxidation Numbers Oxidation Numbers for Formulas and Names
Using oxidation numbers, the Stock system, introduced in the previous section for naming ionic compounds, can be used as an alternative to the prefix system for naming binary molecular compounds
Prefix system
Stock system
PCl3
phosphorus trichloride
phosphorus(III) chloride
PCl5
phosphorus pentachloride
phosphorus(V) chloride
N2O
dinitrogen monoxide
nitrogen(I) oxide NO
nitrogen monoxide
nitrogen(II) oxide
Mo2O3
dimolybdenum trioxide
molybdenum(III) oxide

15. Practice Problems
Assign oxidation numbers to each atom in the following compounds or ions: HF
CI4
H2O
PI3
CS2
Na2O2
H2CO3
NO2ˉ