# Explain what gamma radiation is and describe why emitting gamma radiation does not change the mass number or atomic number of a nucleus. Include in your answer a description of what happens inside the nucleus during gamma emission.

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

> Some radioactive nuclei release energy after emitting an alpha or beta particle by emitting gamma radiation.

## Mark scheme (5 marks)

1. Gamma radiation is a high-frequency / short-wavelength electromagnetic wave / ray
2. Gamma radiation has no mass (or mass number of zero)
3. Gamma radiation has no charge (or atomic number / proton number of zero)
4. Because gamma radiation carries no mass and no charge, the mass number and atomic number of the nucleus remain unchanged
5. The nucleus releases excess energy (moves from a higher energy state to a lower / more stable energy state) during gamma emission

## Key terms

- [gamma radiation](https://www.gradenine.co.uk/glossary/gamma-radiation)
- [mass number](https://www.gradenine.co.uk/glossary/mass-number)
- [atomic number](https://www.gradenine.co.uk/glossary/atomic-number)

## Related

- [Revision notes for WJEC A-Level 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-gamma-radiation-is-and-427ffec4) · Published by Druglandscape Ltd.