# Explain why potassium reacts more vigorously with water than lithium does.

> Cambridge International IGCSE Chemistry (0620) — 8.2 Group I properties · Explain · 4 marks

> Group I metals all react with water, but the violence of the reaction increases down the group.

## Mark scheme (4 marks)

1. Potassium has more electron shells (energy levels) than lithium
2. The outer electron in potassium is further from the nucleus / is more shielded
3. The outer electron is lost more easily in potassium
4. Therefore potassium is more reactive / reacts more vigorously with water

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