# Explain why atoms have no overall electrical charge, and describe how the number of protons in an atom determines its identity as a specific element.

> Edexcel A-Level Chemistry (9CH0) — 1.1 Atomic structure · Explain · 5 marks

> All matter is made up of atoms. Each atom contains a nucleus surrounded by electrons arranged in shells. The nucleus contains protons and neutrons. The relative charges and masses of these subatomic particles are well established.

## Mark scheme (5 marks)

1. Protons have a relative charge of +1 (positive)
2. Electrons have a relative charge of −1 (negative)
3. The number of protons equals the number of electrons, so the charges cancel / balance out, giving no overall charge
4. The number of protons in an atom is called the atomic number (proton number)
5. Each element has a unique number of protons / atomic number, so the number of protons identifies which element the atom is

## Key terms

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

## Related

- [Revision notes for Edexcel A-Level Chemistry (9CH0)](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-why-atoms-have-no-overall-ec796a9a) · Published by Druglandscape Ltd.