Question
Diamond and graphite are both made entirely of carbon atoms. Yet diamond is extremely hard and does not conduct electricity, while graphite is soft and slippery and conducts electricity.
Explain these differences in terms of bonding and structure.
[6 marks]
Mark scheme — level 3 (5–6):
- In diamond, each carbon is covalently bonded to 4 other carbons (B1) in a 3-D rigid network (B1).
- All 4 outer electrons are used in covalent bonds, so there are no free electrons to carry charge (B1).
- In graphite, each carbon is covalently bonded to 3 other carbons in flat layers (B1).
- Layers are held together by weak intermolecular forces, allowing them to slide → soft and slippery (B1).
- Each carbon has one delocalised electron, free to move along the layer → graphite conducts electricity (B1).
6 marks · take your time before peeking.
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Generated by TopMyGrade AI · cross-check official sources before relying on the mark-scheme phrasing.