Explain why graphite can conduct electricity but diamond cannot.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Model answer (4 marks)
Graphite contains delocalised electrons that are free to move through the layers, allowing charge to be carried and the material to conduct electricity. In diamond every carbon atom uses its four outer electrons to form strong covalent bonds with four neighbours, so there are no free charge carriers and diamond does not conduct.
Examiner tips
- Mention delocalised electrons in graphite and covalent bonding in diamond
- Explain how free electrons enable conduction
- Keep answer concise and use correct terminology
- Show clear link between structure and property
Common mistakes
- Confusing graphite with diamond structure
- Failing to state that diamond has no free electrons
- Using vague terms like "electrons" without explaining delocalisation
Mark scheme (4 marks)
- Graphite has delocalised (free) electrons
- These delocalised electrons can move through the structure to carry charge / conduct electricity
- In diamond, all four outer electrons of each carbon atom are used to form covalent bonds
- Therefore diamond has no charged particles free to move, so it cannot conduct electricity
Key terms in this question
Related
- All AQA GCSE Chemistry (8462) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
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