# Explain how electrons are arranged in an atom and describe what happens to this arrangement when an atom absorbs or releases energy.

> AQA A-Level Chemistry (7405) — 3.1.1 Atomic structure · Explain · 5 marks

## Mark scheme (5 marks)

1. Electrons occupy shells (energy levels) around the nucleus
2. Each shell can hold a limited / specific number of electrons
3. Electrons occupy the lowest available energy level / shell first (closest to the nucleus filled first)
4. When an atom absorbs energy, an electron moves to a higher energy level / shell (further from the nucleus)
5. When an electron falls back to a lower energy level / shell, energy is released (as electromagnetic radiation / light)

## Related

- [Revision notes for AQA A-Level Chemistry (7405)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
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