# Carbon-14 is a radioactive isotope used in radioactive dating of ancient organic materials. Carbon-14 undergoes beta decay and has a half-life of approximately 5700 years. Explain why carbon-14 is suitable for dating ancient organic materials, and describe the hazards associated with handling a sample that has been contaminated with carbon-14.

> OCR A-Level Physics B: Advancing Physics (H557) — 6.3 Nuclear and particle physics · Explain · 5 marks

> Archaeologists use radioactive dating to estimate the age of organic artefacts such as bones and wood. Carbon-14 is continuously produced in the atmosphere and absorbed by living organisms. When an organism dies, the carbon-14 in its body begins to decay and is no longer replenished.

## Mark scheme (5 marks)

1. Carbon-14 has a long enough half-life (approximately 5700 years) to remain detectable in ancient samples
2. The ratio of decayed to undecayed carbon-14 nuclei can be used to calculate the age of the sample
3. Beta particles have medium penetrating power and are stopped by a few millimetres of aluminium
4. Radioactive contamination from carbon-14 on the skin or clothing means the radioactive atoms remain on the object, continuing to emit beta radiation and posing a long-term hazard
5. Beta particles are ionising and can damage living cells or DNA, making contamination a health hazard

## Key terms

- [radioactive dating](https://www.gradenine.co.uk/glossary/radioactive-dating)
- [half-life](https://www.gradenine.co.uk/glossary/half-life)

## Related

- [Revision notes for OCR A-Level Physics B: Advancing Physics (H557)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
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Source: [GradeNine](https://www.gradenine.co.uk/q/carbon-14-is-a-radioactive-isotope-used-e8525a2d) · Published by Druglandscape Ltd.