# Sodium and potassium are both elements in Group 1 of the periodic table. When a small piece of potassium is placed on cold water it reacts more vigorously than sodium does under the same conditions. Explain why potassium reacts more vigorously with cold water than sodium does.

> WJEC A-Level Chemistry (Wales) — 2.2 Group 1, 2 and 7 · Explain · 5 marks

> Group 1 elements all react with cold water to produce a metal hydroxide and hydrogen gas. The reactions become more vigorous as you move down the group.

## Mark scheme (5 marks)

1. Potassium has more electron shells than sodium / potassium's outer electron is in a shell further from the nucleus than sodium's
2. The outer electron in potassium is less strongly attracted to / held by the nucleus than in sodium
3. The outer electron in potassium is lost more easily than in sodium
4. Elements in Group 1 react by losing their single outer electron to form a 1+ ion
5. Reactivity increases down Group 1 because it becomes progressively easier to lose the outer electron as you go down the group

## Key terms

- [Group 1](https://www.gradenine.co.uk/glossary/group-1)

## Related

- [Revision notes for WJEC A-Level Chemistry (Wales)](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/sodium-and-potassium-are-both-elements-00031907) · Published by Druglandscape Ltd.