Oxidation Numbers Worksheet
Directions: Use the Rules for Assigning Oxidation Numbers to determine the oxidation number assigned to each
element in each of the given chemical formulas.
Formula
Element and Oxidation
Number
Formula
Element and Oxidation Number
1.
Cl2
Cl
17.
Na2O2
Na
O
2.
Cl-
Cl
18.
SiO2
Si
O
3.
Na
Na
19.
CaCl2
Ca
Cl
4.
Na+
Na
20.
PO43-
P
O
5.
O2
O
21.
MnO2
Mn
O
6.
N2
N
22.
FeO
Fe
O
7.
Al+3
Al
23.
Fe2O3
Fe
O
8.
H2O
H
O
24.
H2O2
H
O
9.
NO3-
N
O
25.
CaO
Ca
O
10.
NO2
N
O
26.
H2S
H
S
11.
Cr2O72-
Cr
O
27.
H2SO4
H
S
O
12.
KCl
K
Cl
28.
NH4Cl
N
H
Cl
13.
NH3
N
H
29.
K3PO4
K
P
O
14.
CaH2
Ca
H
30.
HNO3
H
N
O
15.
SO42-
S
O
31.
KNO2
K
N
O
16.
VO
V
O
32.
KClO4
K
Cl
O
Element and Oxidation
Number
Formula
Formula
Element and Oxidation Number
F2
F
Na2O
Na
O
F-
F
PO4-3
P
O
Ba
Ba
N2O3
N
O
Ba+2
Ba
PO43-
P
O
O3
O
MnO4
Mn
O
H2
N
Fe 2O3
Fe
O
Fe+3
Fe
SnO
Sn
O
CH4
C
H
SnO2
Sn
O
CO3-2
C
O
OF2
O
F
CO2
C
O
NH4+1
N
H
N2O5
N
O
H2SO3
H
S
O
Li4C
Li
C
(NH4)2S
N
H
S
SO3
S
S
Li3PO4
Li
P
O
CaO
Ca
O
HNO2
H
N
O
SO32-
S
O
KClO2
K
Cl
O
ClO21-
Cl
O
K2Cr2O7
K
Cr
O
ClO1-
Cl
O
UO2F2
U
O
F
ClO31-
Cl
O
Al2(SO4)3
Al
S
O