Melting point: The temperature at which a solid changes to a liquid. Temperature stays constant during melting as energy breaks intermolecular bonds.
Boiling point: The temperature at which a liquid changes to a gas throughout the bulk liquid. Temperature stays constant during boiling.
Internal energy: The total kinetic and potential energy of all the particles in a substance.
Latent heat: The energy needed to change state without changing temperature. It goes into breaking or forming bonds (changing potential energy).
Evaporation: A surface process where higher-energy particles escape from a liquid below its boiling point. Distinct from boiling (which happens throughout the liquid).
Sublimation: A direct change from solid to gas without passing through the liquid state (e.g. dry ice / frozen CO₂).
This definitions covers Key Definitions 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 8 of 13 in this topic. Make sure you can use the exact wording confidently, because definition marks are often lost through vague language.
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.