# Lithium fluoride is an ionic compound with a giant lattice structure. Explain why lithium fluoride dissolves readily in water yet does not conduct electricity as a solid.

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

> Lithium fluoride is widely used in specialist optical equipment. It is an ionic compound in which lithium ions (Li⁺) and fluoride ions (F⁻) are held together by strong electrostatic forces in a giant lattice structure.

## Mark scheme (4 marks)

1. In the solid state, the ions are held in fixed positions within the giant lattice (and so cannot move)
2. Without free-moving ions, charge cannot be carried / conducted
3. When dissolved in water, the giant lattice breaks down / the ions separate and become free to move through the solution
4. The free ions in solution can carry electrical charge, allowing the solution to conduct electricity

## Key terms

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

## Related

- [Revision notes for Pearson Edexcel International GCSE Chemistry (4CH1)](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/lithium-fluoride-is-an-ionic-compound-39a4d605) · Published by Druglandscape Ltd.