This key facts covers The Six Changes of State within States of Matter for GCSE Physics. Revise States of Matter in Particle Model for GCSE Physics with 13 exam-style questions and 30 flashcards. This topic appears less often, but it can still be a useful differentiator on mixed-topic papers. It is section 6 of 13 in this topic. Use this key facts to connect the idea to the wider topic before moving on to questions and flashcards.
📚 The Six Changes of State
| Change | From → To | Energy | Bonds |
|---|---|---|---|
| Melting | Solid → Liquid | IN (absorbed) | Breaking |
| Freezing | Liquid → Solid | OUT (released) | Forming |
| Boiling/Evaporating | Liquid → Gas | IN (absorbed) | Breaking |
| Condensing | Gas → Liquid | OUT (released) | Forming |
| Sublimation | Solid → Gas | IN (absorbed) | Breaking |
| Deposition | Gas → Solid | OUT (released) | Forming |
Key insight: Energy IN = bonds breaking; Energy OUT = bonds forming
Quick Check: When water boils at 100°C, what is happening to the energy supplied and why does the temperature not rise above 100°C during boiling?
The energy supplied is being used to break bonds between water molecules (increasing potential energy), not to increase their speed (kinetic energy). Since temperature depends on kinetic energy only, it stays constant at 100°C until all liquid has vaporised.
Practice questions for States of Matter
In which state of matter are particles arranged in a regular pattern and only vibrate about fixed positions?
Explain what happens to the particles in a solid when it is heated until it melts. Include what happens to the temperature during melting.