Oxidation is any electrochemical process which involves the formal oxidation state of an atom or atoms (within a molecule) being increased by the removal of electrons. E.g. iron(II) can be oxidized to iron(III):
- Fe2+ → Fe3+ + e-
Formerly, oxidation simply meant the reaction of a material with oxygen (hence the name). However, when the term is now used it is normally in the more general sense. Some common forms of oxidation are the tarnishing of silverware and the rusting of iron:
- 4Fe + 3O2 → 2 Fe2O3.
In organic chemistry, stepwise oxidation of a hydrocarbon produces water and, successively, an alcohol, an aldehyde or a ketone, carboxylic acid, and then a peroxide.
In inorganic chemistry terms, incompletely oxidized carbon takes the form of carbonate, bicarbonate or carbon monoxide.
The opposite of oxidation is reduction. A reaction involving both processes is called a redox reaction.