Explain why metals have high melting points and why they can be drawn into wires without breaking.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Copper is used to make electrical cables. It can be pulled into long, thin wires and does not melt under normal operating conditions.
Model answer (4 marks)
Metals have a giant lattice of regularly arranged positive ions.
The strong electrostatic attraction between these ions and the delocalised electrons requires a large amount of energy to break, giving metals high melting points.
When a force is applied the layers of ions can slide over one another.
Because the delocalised electrons keep the attraction between the layers, the structure does not break, so the metal is ductile and can be drawn into wires.
The strong electrostatic attraction between these ions and the delocalised electrons requires a large amount of energy to break, giving metals high melting points.
When a force is applied the layers of ions can slide over one another.
Because the delocalised electrons keep the attraction between the layers, the structure does not break, so the metal is ductile and can be drawn into wires.
Examiner tips
- Use the terms ‘giant lattice’, ‘delocalised electrons’ and ‘ductile’ as the mark scheme rewards specific terminology.
- Show the logical link: lattice → strong attraction → high melting point; attraction + delocalised electrons → ductility.
- Keep the answer concise – 4 points can be covered in 4 short sentences.
Common mistakes
- Confusing ‘high melting point’ with ‘high boiling point’ or vice‑versa.
- Using ‘metallic bond’ instead of describing the lattice and delocalised electrons.
- Failing to mention that the electrons allow layers to slide without breaking the structure.
Mark scheme (4 marks)
- Metals have a giant lattice / regular arrangement of positive ions
- Strong electrostatic attraction between positive ions and delocalised electrons requires a lot of energy to overcome, giving a high melting point
- Layers of ions can slide over one another when a force is applied
- The delocalised electrons maintain the attraction throughout, so the structure does not break / the metal is ductile
Related
- All Cambridge International IGCSE Chemistry (0620) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
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