# A radioactive source emits beta particles. Explain what a beta particle is and describe how beta emission changes the nucleus of the atom from which it is released.

> WJEC GCSE Physics (Wales) — 2.4 The atom, the nucleus and radioactivity · Explain · 4 marks

## Mark scheme (4 marks)

1. A beta particle is a fast-moving electron (emitted from the nucleus)
2. A neutron changes into a proton (and a beta particle) during beta emission
3. The atomic number (proton number) increases by one
4. The mass number (nucleon number) stays the same / is unchanged

## Key terms

- [beta particle](https://www.gradenine.co.uk/glossary/beta-particle)
- [nucleus](https://www.gradenine.co.uk/glossary/nucleus)

## Related

- [Revision notes for WJEC GCSE Physics (Wales)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

---
Source: [GradeNine](https://www.gradenine.co.uk/q/a-radioactive-source-emits-beta-particles-0a482e4d) · Published by Druglandscape Ltd.