Oxidation Numbers (Oxidation States)

Key Concepts

An oxidation number (oxidation state) is the charge an atom would carry if the molecule or ion were completely ionic.
For a neutral molecule or compound, the sum of the oxidation numbers (states) for each element in the molecule equals 0.
For a charged molecule (ion), the sum of the oxidation numbers (states) for each element in the ion equals the charge on the ion.

Fluorine is assigned an oxidation number of -1 in compounds
Oxygen is assigned an oxidation number of -2 in compounds
Except in
- Peroxides
- Superoxides
- Oxygen fluorides
Hydrogen is assigned an oxidation of +1 in compounds
Group 1 elements (Alkali Metals) are assigned an oxidation number of +1 in compounds
Group 2 elements (Alkaline-earth metals) are assigned an oxidation number of +2 in compounds
An atom of any element in the free state has an oxidation number of 0
Any monatomic ion has an oxidation number equal to its charge
The sum of the oxidation numbers of all the atoms in formula equals the electrical charge shown with the formula