# A lithium atom has an atomic number of 3 and a mass number of 7. Describe the structure of a lithium atom in terms of its subatomic particles, including their charges, relative masses, and locations within the atom.

> OCR GCSE Chemistry A: Gateway Science (J248) — C1.2 Atomic structure · Describe · 4 marks

> Lithium is a soft metal used in rechargeable batteries. Understanding its atomic structure helps chemists predict how it will react.

## Mark scheme (4 marks)

1. The nucleus contains 3 protons (positively charged, relative mass 1) AND 4 neutrons (neutral, relative mass 1)
2. 3 electrons orbit the nucleus / are found in shells / energy levels around the nucleus
3. Electrons are negatively charged with negligible / very small relative mass
4. Most of the mass is in the nucleus / the nuclear radius is much smaller than the atomic radius / the atom is mostly empty space

## Key terms

- [atomic number](https://www.gradenine.co.uk/glossary/atomic-number)
- [mass number](https://www.gradenine.co.uk/glossary/mass-number)
- [subatomic particles](https://www.gradenine.co.uk/glossary/subatomic-particles)

## Related

- [Revision notes for OCR GCSE Chemistry A: Gateway Science (J248)](https://www.gradenine.co.uk/learn)
- [How to answer "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/a-lithium-atom-has-an-atomic-cfc7809d) · Published by Druglandscape Ltd.