# Graphite and diamond are both giant covalent structures made entirely of carbon atoms, yet they have very different properties. Explain why graphite can conduct electricity whilst diamond cannot, and explain why both substances have high melting points.

> OCR A-Level Chemistry A (H432) — 2.4 Electrons, bonding and structure · Explain · 5 marks

> Graphite is used as an electrode material in electrolysis cells. Diamond is used in cutting tools. Both are allotropes of carbon.

## Mark scheme (5 marks)

1. In graphite, each carbon atom forms three covalent bonds (with three other carbon atoms), leaving one electron per carbon atom that is not used in bonding.
2. In graphite, this electron is delocalised (free to move) and can carry charge, allowing graphite to conduct electricity.
3. In diamond, each carbon atom forms four covalent bonds with four other carbon atoms, so there are no delocalised electrons.
4. Both substances have many strong covalent bonds throughout the giant covalent structure.
5. A large amount of energy is needed to break these strong covalent bonds, which is why both substances have high melting points.

## Key terms

- [giant covalent structure](https://www.gradenine.co.uk/glossary/giant-covalent-structure)
- [graphite](https://www.gradenine.co.uk/glossary/graphite)
- [diamond](https://www.gradenine.co.uk/glossary/diamond)

## 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)
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Source: [GradeNine](https://www.gradenine.co.uk/q/graphite-and-diamond-are-both-giant-a3a6375c) · Published by Druglandscape Ltd.