Reference Work Entry

Encyclopedia of Astrobiology

pp 1194-1195


  • Concepción AlonsoAffiliated withUniversidad Autonoma de Madrid Email author 


Combustion; Corrosion; Rusting


Electron donor, reducing agent, reductive


Oxidation can be defined with different terms such as: the loss of electrons or hydrogen, or the gain of oxygen by an atom or a molecule.


Oxidation in Terms of Electron Transfer

Oxidation is the loss of electrons.

For example, in the reaction between iron and copper sulfate solution
$$ {\text{Fe}} + {\text{CuS}}{{\text{O}}_4} \to {\text{Cu}} + {\text{FeS}}{{\text{O}}_4} $$
copper sulfate and iron sulfate are both ionic compounds. If rewritten as an ionic equation, it turns out that sulfate ions are spectator ions and the reaction can be written as:
$$ {\text{Fe}} + {\text{C}}{{\text{u}}^{{2} + }} \to {\text{Cu}} + {\text{F}}{{\text{e}}^{{2} + }} $$
where the iron is oxidized from metal iron (Feo) to ferrous iron (Fe2+) by the loss of two electrons: ...
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