# Explain why graphite can conduct electricity but diamond cannot, even though both are forms of carbon.

> AQA A-Level Chemistry (7405) — 3.1.3 Bonding · Explain · 5 marks

## Mark scheme (5 marks)

1. Graphite has delocalised electrons (that are free to move)
2. In graphite each carbon atom forms three covalent bonds / only three of its four outer electrons are used in bonding
3. These delocalised electrons can carry charge / move through the structure when a voltage is applied
4. In diamond every carbon atom forms four covalent bonds / all four outer electrons are used in bonding
5. So diamond has no delocalised / free electrons, therefore it cannot conduct electricity

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