Question

Why is losing electrons called oxidation?

Answer 1

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

For example, in the reaction

`"2Mg" + "O"_2 → "2MgO"`,

the `"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"` to `"O"`.

`"Mg"→ "Mg"^(2+) + 2"e"^-`
`"O" + "2e"^(-) → "O"^(2-)`

`"Mg"^(2+) + "O"^(2-) → "MgO"`

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

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