1
Q
Free elements (uncombined state)
A
Have an oxidation number of zero.
NOTE: Free elements do NOT include ions.
2
Q
In monoatomic ions…
A
The oxidation number is equal to the charge on the ion.
3
Q
Oxygen
A
Oxygen usually has an oxidation number of -2. In H2O2 and O22, it is -1.
4
Q
Hydrogen
A
Hydrogen has an oxidation number of +1, except when it is bonded to metals in binary compounds. In such cases, it’s oxidation number is -1.
5
Q
Alkali metals
A
+1
6
Q
Alkaline earth metals
A
+2
7
Q
Fluorine
A
-1
8
Q
In molecules or ions
A
The sum of the oxidation numbers of all the atoms in the molecule or ion is equal to the charge on the molecule of ion.
9
Q
Do oxidation numbers have to be integers?
A
No, they can be fractions.
