Oxidation - GCSE Chemistry Definition

Reviewed by: Alexandra Brennan

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What is oxidation?

In GCSE Chemistry, oxidation can be defined as:

  • the gain of oxygen

  • the loss of electrons

When magnesium reacts with oxygen to form magnesium oxide the following reactions happens:

2Mg + O₂ → 2MgO

  • Magnesium is oxidised as it gains oxygen.

  • The magnesium atom also loses electrons to form magnesium ions:

Mg → Mg2++ 2e

Oxidation is often seen in reactions like rusting (iron + oxygen → iron oxide) and combustion (burning fuels).

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Alexandra Brennan

Reviewer: Alexandra Brennan

Expertise: Chemistry Content Creator

Alex studied Biochemistry at Newcastle University before embarking upon a career in teaching. With nearly 10 years of teaching experience, Alex has had several roles including Chemistry/Science Teacher, Head of Science and Examiner for AQA and Edexcel. Alex’s passion for creating engaging content that enables students to succeed in exams drove her to pursue a career outside of the classroom at SME.

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