# Sodium chloride is an ionic compound. Explain why sodium chloride has a high melting point and does not conduct electricity when solid, but does conduct electricity when molten.

> OCR A-Level Chemistry A (H432) — 2.1 Atoms, compounds, molecules and equations · Explain · 5 marks

> Sodium chloride is formed when sodium, a metal, reacts with chlorine, a non-metal. The resulting compound is used widely in food preservation and the chemical industry.

## Mark scheme (5 marks)

1. Sodium chloride is held together by strong electrostatic forces (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 fixed positions (in a lattice) and cannot move
4. Therefore, charge cannot be carried through the solid, so it does not conduct electricity
5. When molten, the ions are free to move and can carry charge, so it conducts electricity

## Key terms

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

## Related

- [Revision notes for OCR A-Level Chemistry A (H432)](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)

---
Source: [GradeNine](https://www.gradenine.co.uk/q/sodium-chloride-is-an-ionic-compound-6e62d284) · Published by Druglandscape Ltd.