Explain why metals are good conductors of electricity.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Model answer (4 marks)
Metals contain delocalised electrons.
These electrons are free to move through the crystal lattice.
When a voltage or potential difference is applied, the delocalised electrons drift in the same direction.
This movement of charged particles carries electrical energy, i.e. constitutes an electric current.
These electrons are free to move through the crystal lattice.
When a voltage or potential difference is applied, the delocalised electrons drift in the same direction.
This movement of charged particles carries electrical energy, i.e. constitutes an electric current.
Examiner tips
- Use the exact terms ‘delocalised electrons’ and ‘electric current’. Show the chain: delocalised electrons → free movement → drift under voltage → current. Keep answer concise to fit 4 marks.
Common mistakes
- Confusing metallic bonds with ionic bonds. Failing to mention the role of voltage. Using vague phrases like ‘free electrons’ without linking to current.
Mark scheme (4 marks)
- Metals contain delocalised electrons
- The delocalised electrons are free to move through the structure
- When a voltage / potential difference is applied, the delocalised electrons move in the same direction
- This movement of charged particles carries electrical energy / constitutes an electric current
Key terms in this question
Related
- All AQA GCSE Chemistry (8462) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →