Copyright © 2008 Pearson Prentice Hall, Inc.
Chapter 4/
36
Oxidation-Reduction (Redox)
Reactions
b)
Oxygen
usually
has an oxidation number of -2.
H
O
1-
-2
+1
H
H
Ca
-1
-1
+2
3.
An atom in a polyatomic ion or in a molecular
compound usually has the same oxidation number
it would have if it were a monatomic ion.
a)
Hydrogen can be either +1 or -1.
O
H
O
-1
+1
-1
H
H
O
+1
+1
-2
H
+1
H bonded to a nonmetal has an oxidation number of +1.
H bonded to a metal has an oxidation number of -1.
In peroxides, O
2
2-
, oxygen has an oxidation number of -1.