# Neon has two main isotopes: neon-20 and neon-22. The relative atomic mass of neon is 20.2. Explain what this tells us about the abundance of neon-20 compared to neon-22, and explain why the relative atomic mass is not a whole number.

> WJEC GCSE Chemistry (Wales) — 2.4 Chemical analysis · Explain · 4 marks

## Mark scheme (4 marks)

1. Neon-20 is more abundant than neon-22
2. The relative atomic mass is closer to 20 than to 22, which shows neon-20 is the dominant isotope
3. Relative atomic mass is an average value that takes account of the abundance of the isotopes of the element
4. Because it is a weighted average of two isotopes with different masses, the result is not a whole number

## Key terms

- [isotope](https://www.gradenine.co.uk/glossary/isotope)
- [relative atomic mass](https://www.gradenine.co.uk/glossary/relative-atomic-mass)
- [abundance](https://www.gradenine.co.uk/glossary/abundance)

## Related

- [Revision notes for WJEC GCSE Chemistry (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/neon-has-two-main-isotopes-neon-20-b594fac9) · Published by Druglandscape Ltd.