Pearson Edexcel International GCSE Chemistry · specification 4CH1 · Paper 1 | Whole paper: Core content, all four topics · Free · no account needed
1(a) States of matter (4CH1 specification)
The particle model, the changes of state it explains, and the evidence for particles moving.
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The 2 Incandio pages that teach this — each explained in full, then proved in marked questions, taught back to an AI pupil and defended in a debate. Completely free.
- The Three States of Matter — What the particles are doing in a solid, a liquid and a gas — and what really changes when ice melts.
- Pure Substances, Mixtures and How to Separate Them — Why a pure substance melts at one temperature, and which separation technique to reach for when.
The teaching route this belongs to: Topic 1 · Principles of chemistry (Chemistry) — the lessons in order, with every gate.
Specification coverage
Topic 1 Principles of chemistry (a) States of matter — statements 1.1–1.4
Assessment objectives: AO1, AO2. Suggested learning time: 45 minutes.
Required knowledge
- The arrangement, movement and relative energy of particles in solids, liquids and gases
- The names of the changes of state and what happens to the particles during each
- How the particle model explains diffusion
- The effect of temperature and molecular mass on the rate of diffusion
Required skills
- Explain a physical property using the particle model
- Interpret a heating or cooling curve
- Explain diffusion results in terms of relative molecular mass
How it is examined
- Multiple-choice and short-answer recall
- Application of the content to an unfamiliar context
- Extended open-response, marked on the quality of a connected explanation
Common mistakes
- Saying particles in a solid 'do not move'. They vibrate about fixed positions.
- Describing melting as particles 'getting bigger'. The particles are unchanged; their arrangement and energy change.
- Explaining a plateau on a heating curve as 'nothing happening'. Energy is being used to break forces between particles.
This page maps the specification. The pages above teach it, and the Chemistry lessons hold the whole course — completely free.