# Explain why chlorine is able to displace bromide ions from a solution of potassium bromide, but iodine is not able to displace bromide ions from the same solution.

> Cambridge International IGCSE Chemistry (0620) — 8.3 Group VII properties · Explain · 4 marks

## Mark scheme (4 marks)

1. Chlorine is more reactive than bromine (or iodine is less reactive than bromine)
2. A more reactive halogen displaces a less reactive halogen from its salt solution (displacement reaction)
3. Chlorine atoms gain electrons more easily than bromine atoms (because the outer shell is closer to the nucleus / less shielding)
4. Iodine cannot displace bromide ions because iodine is less reactive than bromine / iodine gains electrons less easily than bromine

## Key terms

- [bromide ions](https://www.gradenine.co.uk/glossary/bromide-ions)

## Related

- [Revision notes for Cambridge International IGCSE Chemistry (0620)](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/explain-why-chlorine-is-able-to-1eb6a207) · Published by Druglandscape Ltd.