# Neon exists as three naturally occurring isotopes: neon-20, neon-21, and neon-22. State what is meant by the term isotopes, and describe how the atoms of neon-20 and neon-22 are similar and how they differ.

> Cambridge International IGCSE Chemistry (0620) — 2.3 Isotopes · State and Describe · 4 marks

## Mark scheme (4 marks)

1. Isotopes are atoms of the same element with the same number of protons but different numbers of neutrons
2. Neon-20 and neon-22 have the same number of protons (10 protons)
3. Neon-20 and neon-22 have the same number of electrons (10 electrons) / same electronic structure
4. Neon-20 and neon-22 have different numbers of neutrons (neon-20 has 10 neutrons; neon-22 has 12 neutrons)

## Key terms

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

## Related

- [Revision notes for Cambridge International IGCSE Chemistry (0620)](https://www.gradenine.co.uk/learn)
- [How to answer "State and Describe" 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/neon-exists-as-three-naturally-occurring-6c9b875e) · Published by Druglandscape Ltd.