# A sample of radioactive material emits alpha particles. Describe the nature of an alpha particle and explain what happens to the nucleus of an atom when it emits an alpha particle.

> WJEC A-Level Physics (Wales) — 3.5 Nuclear decay · Describe and Explain · 5 marks

## Mark scheme (5 marks)

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

## Key terms

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

## Related

- [Revision notes for WJEC A-Level Physics (Wales)](https://www.gradenine.co.uk/learn)
- [How to answer "Describe and 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/a-sample-of-radioactive-material-emits-aa97441f) · Published by Druglandscape Ltd.