# Ionic compounds such as sodium chloride have high melting points and conduct electricity when molten but not when solid. Explain these two properties in terms of the structure and bonding of ionic compounds.

> Pearson Edexcel International GCSE Chemistry (4CH1) — 1.6 Ionic compounds · Explain · 4 marks

## Mark scheme (4 marks)

1. Ionic compounds contain strong electrostatic forces (of attraction) between oppositely charged ions
2. A large amount of energy is needed to overcome these strong electrostatic forces, so the melting point is high
3. When solid, the ions are held in a fixed lattice / are not free to move
4. When molten, the ions are free to move (and carry charge), so the compound conducts electricity

## Key terms

- [ionic compound](https://www.gradenine.co.uk/glossary/ionic-compound)
- [ion](https://www.gradenine.co.uk/glossary/ion)

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Source: [GradeNine](https://www.gradenine.co.uk/q/ionic-compounds-such-as-sodium-chloride-ad0e2fe0) · Published by Druglandscape Ltd.