# Explain what happens to the nucleus of an atom during alpha decay.

> WJEC GCSE Physics (Wales) — 2.9 Nuclear decay and nuclear energy · Explain · 4 marks

> Radioactive decay is a process in which an unstable nucleus loses energy by emitting radiation. Alpha decay is one type of radioactive decay.

## Mark scheme (4 marks)

1. The nucleus emits an alpha particle
2. An alpha particle consists of 2 protons and 2 neutrons
3. The atomic number (proton number) of the nucleus decreases by 2
4. The mass number (nucleon number) of the nucleus decreases by 4

## Key terms

- [alpha decay](https://www.gradenine.co.uk/glossary/alpha-decay)
- [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)

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Source: [GradeNine](https://www.gradenine.co.uk/q/explain-what-happens-to-the-nucleus-540e288a) · Published by Druglandscape Ltd.