KS3 (Years 7–9) · Chemistry
Particle Model of Matter
What is it
Students learn to explain the properties of solids, liquids and gases in terms of the arrangement, movement and energy of their particles, and how changes of state are explained by particles gaining or losing energy.
Why it matters
This particle-level explanation replaces the simpler KS2 description with real scientific reasoning — the same model used throughout GCSE chemistry and physics to explain pressure, density and diffusion.
Exam tip
Always describe particles in solids/liquids/gases using all three features together — arrangement, movement, and relative energy — answers that mention only one feature rarely score full marks.
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