Oxidation: GCSE Chemistry Definition

Written by: Alexandra Brennan

Reviewed by: Philippa Platt

Published

10 February 2025

Last updated

10 February 2025

Contents

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).

Oxidation Revision Resources to Ace Your Exams

For more information about oxidation check out the following resources:

Explore our GCSE Chemistry Revision Resources.

Sign up for articles sent directly to your inbox

Receive news, articles and guides directly from our team of experts.

Share this article

Author

Reviewer

Author: Alexandra Brennan

Expertise: Chemistry

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.

Author: Philippa Platt

Expertise: Chemistry

Philippa has worked as a GCSE and A level chemistry teacher and tutor for over thirteen years. She studied chemistry and sport science at Loughborough University graduating in 2007 having also completed her PGCE in science. Throughout her time as a teacher she was incharge of a boarding house for five years and coached many teams in a variety of sports. When not producing resources with the chemistry team, Philippa enjoys being active outside with her young family and is a very keen gardener

The examiner written revision resources that improve your grades 2x.

Join now