# Fluorine, chlorine, bromine and iodine are all elements in Group 7 of the periodic table. A student states: 'Fluorine is the most reactive element in Group 7 because it has the smallest atom.' Explain why the student's statement is correct, and describe how the reactivity of the Group 7 elements changes going down the group.

> Eduqas A-Level Chemistry — 2.2 Group 1, 2 and 7 · Explain · 5 marks

## Mark scheme (5 marks)

1. Fluorine (or atoms at the top of Group 7) has the fewest electron shells
2. The outer shell (where the new electron is gained) is closer to the nucleus in fluorine
3. Fluorine attracts / gains an electron more easily (or has a stronger attraction for an incoming electron)
4. Reactivity decreases going down Group 7
5. Because going down the group, atoms have more electron shells / the outer shell is further from the nucleus, so an incoming electron is attracted less strongly

## Key terms

- [Group 7](https://www.gradenine.co.uk/glossary/group-7)
- [reactivity](https://www.gradenine.co.uk/glossary/reactivity)

## Related

- [Revision notes for Eduqas A-Level Chemistry](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/fluorine-chlorine-bromine-and-iodine-are-d72bd391) · Published by Druglandscape Ltd.