# Carbon-12 and carbon-14 are both atoms of the element carbon. Explain why these two atoms are described as isotopes of carbon, and state how the number of neutrons in each atom can be determined from nuclide notation.

> Cambridge International IGCSE Physics (0625) — 5.1 The nuclear model of the atom · Explain · 4 marks

> Carbon-12 has a proton number of 6 and a nucleon number of 12. Carbon-14 has a proton number of 6 and a nucleon number of 14.

## Mark scheme (4 marks)

1. Both atoms have the same number of protons (proton number = 6)
2. They have different numbers of neutrons / different nucleon numbers
3. Number of neutrons is found by subtracting the proton number from the nucleon number
4. Correct neutron numbers stated for both: carbon-12 has 6 neutrons and carbon-14 has 8 neutrons

## Key terms

- [isotopes](https://www.gradenine.co.uk/glossary/isotopes)
- [neutrons](https://www.gradenine.co.uk/glossary/neutrons)
- [nuclide notation](https://www.gradenine.co.uk/glossary/nuclide-notation)

## Related

- [Revision notes for Cambridge International IGCSE Physics (0625)](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/carbon-12-and-carbon-14-are-both-atoms-ab2ce8e4) · Published by Druglandscape Ltd.