Explain why the melting point of a substance depends on the strength of the forces between its particles.

WJEC GCSE Chemistry (Wales) — 2.1 Bonding, structure and properties · Explain · 4 marks · View as Markdown

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

When a solid is heated, it eventually melts. Different substances melt at very different temperatures.

Model answer (4 marks)

Energy is needed to overcome the forces between particles.

Stronger forces require more energy to break.

A higher temperature is needed to supply this greater energy.

Thus substances with stronger inter‑particle forces have higher melting points.

Examiner tips

  • Use the exact wording from the mark scheme: "energy is needed to overcome", "stronger forces", "higher temperature", "higher melting points".
  • Show the logical sequence: energy → force strength → temperature → melting point.
  • Keep each point brief and separate.

Common mistakes

  • Confusing melting point with boiling point.
  • Using vague terms like "stronger bonds" without linking to energy required.
  • Not mentioning temperature as the energy source.

Mark scheme (4 marks)

  1. Energy is needed to overcome / break the forces between particles
  2. Stronger forces between particles require more energy to overcome
  3. A higher temperature is needed to supply this greater energy
  4. Therefore substances with stronger forces between their particles have higher melting points

Key terms in this question

melting point

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