Describe the arrangement and movement of particles in a liquid, and explain why a liquid takes the shape of its container but cannot be compressed.

Cambridge International IGCSE Chemistry (0620) — 1.1 Solids, liquids and gases · Describe · 4 marks · View as Markdown

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

Model answer (4 marks)

Particles in a liquid are close together, touching each other but not arranged in a fixed, regular pattern. They move randomly, flowing and sliding past one another. Because the particles can move, a liquid takes the shape of its container. The particles are already very close together, leaving almost no space between them, so a liquid cannot be compressed.

Examiner tips

  • Use the exact wording: "close together, touching but not in a fixed regular arrangement" and "move randomly, can flow and slide past each other".
  • Explain both shape and incompressibility in one sentence each, linking movement to shape and spacing to compressibility.

Common mistakes

  • Saying the particles are in a fixed arrangement or that they are far apart.
  • Claiming a liquid can be compressed or that it has a fixed shape.

Mark scheme (4 marks)

  1. Particles in a liquid are close together / touching but not in a fixed regular arrangement
  2. Particles in a liquid move randomly / can flow / slide past each other
  3. A liquid takes the shape of its container because particles can move / flow and are not held in fixed positions
  4. A liquid cannot be compressed because the particles are already close together / there is no / very little space between particles

Key terms in this question

particles · liquid · arrangement · compressed

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