# Explain what happens to the nucleus of an atom when it undergoes alpha decay.

> Eduqas A-Level Physics — 3.5 Nuclear decay · Explain · 5 marks

> Radioactive nuclei can become more stable by emitting different types of radiation. One of these processes is alpha decay.

## Mark scheme (5 marks)

1. An alpha particle is emitted from the nucleus
2. An alpha particle consists of 2 protons and 2 neutrons
3. The proton number (atomic number) of the nucleus decreases by 2
4. The mass number (nucleon number) of the nucleus decreases by 4
5. A new (different) element is formed because the proton number has changed

## Key terms

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

## Related

- [Revision notes for Eduqas A-Level Physics](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-4c21718c) · Published by Druglandscape Ltd.