# Oxidation

A reaction where a substance gains oxygen or loses electrons. Metals are oxidised when they burn or rust.

Chemistry (school) · Part 07: Metals and electrolysis · Card 3 of 9 · Last updated 2026-10-19

## Analogy

Like a person handing away a coat. Losing electrons is oxidation.

## Example

**Remember OIL**

Oxidation Is Loss of electrons
Mg -> Mg2+ + 2e-

## In practice

When magnesium burns it is oxidised to magnesium oxide.

## Practice

### Flashcards

- **What is oxidation in terms of electrons?** Loss of electrons (OIL RIG).

### Interview questions

**Describe what happens at each electrode in the electrolysis of molten lead bromide.**

- Lead ions move to the cathode and gain electrons
- Lead metal forms at the cathode
- Bromide ions move to the anode and lose electrons
- Bromine gas forms at the anode

## Questions people ask

### Is oxidation always about oxygen?

No. The first idea of oxidation was gaining oxygen, but it is more broadly the loss of electrons. Magnesium reacting with chlorine has no oxygen involved, yet magnesium loses electrons, so it is oxidised. The electron definition covers all cases.

### What is a redox reaction?

Redox is short for reduction and oxidation happening together. Whenever one substance loses electrons, another gains them. In magnesium reacting with copper oxide, magnesium is oxidised and copper ions are reduced. You cannot have one without the other. Rusting and burning are both redox reactions.

## Related concepts

- [Reduction](https://studyvisually.com/learn/science/chemistry-school/chemistry-school-part-7/chemistry-school-part-7-concept-4)
- [Electrolysis](https://studyvisually.com/learn/science/chemistry-school/chemistry-school-part-7/chemistry-school-part-7-concept-7)
- [Electrolyte](https://studyvisually.com/learn/science/chemistry-school/chemistry-school-part-7/chemistry-school-part-7-concept-8)

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