# Explain why the decay constant of a radioactive nuclide is unaffected by changes in temperature or chemical bonding of the nuclide.

> IB DP Physics Standard Level (2023 syllabus) — E.3 Radioactive decay · Explain · 4 marks

> Radioactive decay is a spontaneous process observed in unstable nuclei. Scientists have found that placing a radioactive source in extreme chemical or physical environments does not alter its measured activity.

## Mark scheme (4 marks)

1. Radioactive decay originates within the nucleus, not from the electron cloud or chemical bonds.
2. Temperature changes and chemical bonding only affect the electrons / electron energy levels, not the nucleus.
3. The decay constant is a property of the nucleus alone, determined by the strong nuclear force / nuclear binding energy / nuclear structure.
4. Because the nucleus is unaffected by these external conditions, the probability of decay per unit time (decay constant) remains constant.

## Key terms

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

## Related

- [Revision notes for IB DP Physics Standard Level (2023 syllabus)](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-the-decay-constant-of-0731423e) · Published by Druglandscape Ltd.