<P> Electron transfer (ET) occurs when an electron relocates from an atom or molecule to another such chemical entity . ET is a mechanistic description of a redox reaction, wherein the oxidation state of reactant and product changes . </P> <P> Numerous biological processes involve ET reactions . These processes include oxygen binding, photosynthesis, respiration, and detoxification . Additionally, the process of energy transfer can be formalized as a two - electron exchange (two concurrent ET events in opposite directions) in case of small distances between the transferring molecules . ET reactions commonly involve transition metal complexes, but there are now many examples of ET in organic chemistry . </P>

Reactions in which electrons are transferred between atoms is called
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