Graphene is a single layer of graphite. Describe the structure and bonding in graphene and explain why graphene is able to conduct electricity.

AQA GCSE Chemistry (8462) — 4.2.3 Structure and bonding of carbon · Describe · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Model answer (4 marks)

Each carbon atom in graphene is bonded to three other carbons by
sp^2 covalent bonds, forming a flat hexagonal lattice. The lattice consists of a single layer of carbon atoms arranged in hexagonal rings. Each carbon atom contributes one electron that is not involved in the
sp^2 bonds; this electron is delocalised over the whole sheet. The delocalised electrons are free to move, allowing them to carry electrical charge and thus enabling graphene to conduct electricity.

Examiner tips

  • Use the term "sp^2" to show understanding of hybridisation.
  • Mention the hexagonal lattice explicitly.
  • Explain that the delocalised electrons are free to move to justify conductivity.
  • Keep the answer concise – 4 marks only.

Common mistakes

  • Confusing graphene with bulk graphite or multilayer graphene.
  • Failing to state that each carbon forms three covalent bonds.
  • Not mentioning the delocalised electron or its role in conductivity.

Mark scheme (4 marks)

  1. Each carbon atom forms three covalent bonds with three other carbon atoms
  2. Graphene consists of a single layer of carbon atoms arranged in hexagonal rings
  3. Each carbon atom has one delocalised electron (not used in covalent bonding)
  4. These delocalised electrons are free to move and carry electrical charge / current

Key terms in this question

graphene

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