# Why is losing electrons called oxidation?

May 24, 2015

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

For example, in the reaction

$\text{2Mg" + "O"_2 → "2MgO}$,

the $\text{Mg}$ was said to be oxidized because it gained an oxygen atom.

Eventually, chemists realized that the reaction involved a transfer of electrons from $\text{Mg}$ to $\text{O}$.

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

$\text{Mg"^(2+) + "O"^(2-) → "MgO}$

Since $\text{Mg}$ lost electrons in the process, chemists added a second definition:

$\textcolor{red}{\text{L}}$oss of $\textcolor{red}{\text{E}}$lectrons is $\textcolor{red}{\text{O}}$xidation.