# An atom of uranium-235 has an atomic number of 92. State the number of protons, neutrons, and electrons in a neutral atom of uranium-235, and explain how you determined the number of neutrons.

> Eduqas GCSE Physics — 9.1 Nuclear atom and isotopes · State · 4 marks

## Mark scheme (4 marks)

1. Number of protons = 92
2. Number of electrons = 92 (in a neutral atom)
3. Number of neutrons = 143
4. Neutron number is found by subtracting the atomic number (proton number) from the mass number

## Key terms

- [atomic number](https://www.gradenine.co.uk/glossary/atomic-number)
- [proton](https://www.gradenine.co.uk/glossary/proton)
- [neutron](https://www.gradenine.co.uk/glossary/neutron)
- [electron](https://www.gradenine.co.uk/glossary/electron)
- [neutral atom](https://www.gradenine.co.uk/glossary/neutral-atom)

## Related

- [Revision notes for Eduqas GCSE Physics](https://www.gradenine.co.uk/learn)
- [How to answer "State" 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/an-atom-of-uranium-235-has-an-5eaf8f33) · Published by Druglandscape Ltd.