Oxidation Number

Topic Content:

Oxidation number can be defined as the charge on an ion or it is the number of electrons on the valence shell of an atom or it is the number of electrons required by an atom to acquire a filled electronic structure.

Uses of Oxidation Number:

1. Oxidation number is used in the I.U.P.A.C system of naming chemical compounds

2. It is used in classifying elements into a particular group (family) on the periodic table.

3. It is used to know which atom is oxidized or reduced in a redox reaction.

4. It is used in balancing half-cell equations.

Rules for Calculating Oxidation Number:

1. The oxidation number of all elements in the free state is zero e.g. O₂ = 0, H = 0, Cu = 0, Cl₂ = 0.

2. The oxidation number of an ion is the charge it possesses.

e.g. Na⁺ = +1, Ca²⁺ = +2, Cl^– = -1, SO₄ ^2- = -2, MnO₄ ^1- = -1

3. The sum of the oxidation number of all the atoms in