# Explain what happens to the nucleus of an atom during alpha decay, including how the proton number and nucleon number of the nucleus change.

> Eduqas A-Level Physics — 1.7 Particles and nuclear structure · Explain · 5 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 (5 marks)

1. An alpha particle is emitted from the nucleus
2. An alpha particle consists of 2 protons and 2 neutrons (or is a helium nucleus)
3. The proton number of the nucleus decreases by 2
4. The nucleon number of the nucleus decreases by 4
5. The nucleus becomes a different element (a new nucleus / daughter nucleus is formed)

## Key terms

- [alpha decay](https://www.gradenine.co.uk/glossary/alpha-decay)
- [proton number](https://www.gradenine.co.uk/glossary/proton-number)
- [nucleon number](https://www.gradenine.co.uk/glossary/nucleon-number)
- [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-ef16fffd) · Published by Druglandscape Ltd.