Introduction of oxidation and reduction

Oxidation:"Oxidation is a reaction in which oxygen is added or hydrogen is removed from a substance."

Oxidation can occur in 2 ways:

1) Addition of Oxygen

Oxygen adds on to magnesium to become magnesium oxide.

2) Removal of Hydrogen

Hydrogen is removed from hydroiodic acid to liberate free iodine.

Reduction: "Reduction is a reaction in which oxygen is removed from a substance or hydrogen is added to a substance."

Reduction can also occurs in 2 ways:

1) Removal of Oxygen

Oxygen is removed from copper oxide to form copper metal.

2) Addition of hydrogen

Hydrogen adds to chlorine to form hydrogen chloride gas.