Aluminium is a metal used to make aircraft frames. It has a giant metallic structure. Explain why aluminium is malleable and can conduct electricity.

Pearson Edexcel International GCSE Chemistry (4CH1) — 1.8 Metallic crystals · Explain · 4 marks · View as Markdown

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

Aluminium has a giant metallic structure consisting of a lattice of positive ions surrounded by delocalised electrons.

Model answer (4 marks)

Aluminium has a giant metallic structure consisting of a lattice of positive ions surrounded by delocalised electrons.

The positive ions form layers that can slide over one another; this allows the metal to be deformed without breaking, making it malleable.

The delocalised electrons are free to move throughout the lattice; when a potential difference is applied they drift, carrying charge and producing an electric current, so aluminium conducts electricity.

Examiner tips

  • Use the exact phrase "lattice of positive ions surrounded by delocalised electrons". Explain that ion layers can slide for malleability. State that delocalised electrons move freely to conduct electricity. Keep answer concise to fit 4 marks.

Common mistakes

  • Using the word "atoms" instead of "positive ions". Failing to mention the sliding of ion layers. Confusing conductivity with resistance or mentioning only the metal’s structure without linking to electron movement.

Mark scheme (4 marks)

  1. Aluminium consists of a lattice of positive ions (surrounded by delocalised electrons)
  2. Layers of positive ions can slide over each other (so the metal can change shape without breaking)
  3. The delocalised electrons are free to move (throughout the lattice)
  4. Moving delocalised electrons carry electrical charge / carry a current

Key terms in this question

giant metallic structure · malleable

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