Why is losing electrons called oxidation?

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Answer 1 · 2015-05-24T23:39:31

In the early days of chemistry, oxidation was defined as a gain of oxygen atoms.

For example, in the reaction

$2Mg + O_{2} \to 2MgO$ $"2Mg" + "O"_2 → "2MgO"$ ,

the $Mg$ $"Mg"$ was said to be oxidized because it gained an oxygen atom.

Eventually, chemists realized that the reaction involved a transfer of electrons from $Mg$ $"Mg"$ to $O$ $"O"$ .

$Mg \to {Mg}^{2 +} + 2 e^{-}$ $"Mg"→ "Mg"^(2+) + 2"e"^-$
$O + {2e}^{-} \to O^{2 -}$ $"O" + "2e"^(-) → "O"^(2-)$

${Mg}^{2 +} + O^{2 -} \to MgO$ $"Mg"^(2+) + "O"^(2-) → "MgO"$

Since $Mg$ $"Mg"$ lost electrons in the process, chemists added a second definition:

$L$ $color(red)("L")$ oss of $E$ $color(red)("E")$ lectrons is $O$ $color(red)("O")$ xidation.