Chemical reaction in which a metal is converted to its oxide, or from one oxidization state to a higher state (that is the equivalent of an increase in the number of oxygen atoms for each metal atom. For example, in the reactions –
2Fe + O2 = 2FeO Metallic Iron to Wüstite
6FeO + O2 = 2Fe3O4 Wüstite to Magnetite
4Fe3O4 + O2 = 6Fe2O3 Magnetite to Haematite
iron is progressively oxidized from the metal to its highest oxide, haematite. Another way of looking at these reactions is that oxidation occurs every time the cation (the metallic ion) gains a unit of charge, e.g. Fe2+ goes to Fe3+, or alternative that the cation loses an electron (the charge on an electron is negative – e-)
e.g. Fe3+ e- = Fe2+
Related terms: Reduction, Valency