Fiducia TogetherParticle model and density
Solids, liquids and gases as arrangements of particles, and what density measures.
Please note: This page explains a word or a process in education. It is general information about the system, the law and the guidance in England — not advice about your child, your school or your exam. If a decision is going against you, get advice from one of the free services we link to before you agree to anything or miss a deadline. If you are revising, check your own exam board's specification: boards word things differently and yours is the one that marks you.
What it is
The particle model describes matter as particles whose arrangement and energy differ between states. Density is mass per unit volume.
Where it applies
GCSE physics and combined science, with a required practical on density.
How it works
Changes of state are physical, not chemical: the particles are the same, their arrangement and energy change, and mass is conserved.
Specific heat capacity is the energy to raise 1 kg by 1°C. Specific latent heat is the energy to change state with no temperature change, which is why a heating curve has flat sections.
How to use it in your work
Explain the flat sections of a heating curve as energy going into breaking bonds rather than raising temperature. That is the mark.
For density, measure irregular solids by displacement and say so.
Internal energy is the total kinetic and potential energy of the particles — use the term.
Where to get help
Your teacher, your board's specification for the depth required at your tier, and Bitesize for the diagrams.
Revise this with a song
These are ours. We write revision songs because a lot of people remember a tune when they cannot remember a page, and because revising out loud in the kitchen beats staring at a highlighter.
- The Physics Song The GCSE physics specification, set to music.
Where to read more
Last reviewed 2026-08-28 by Fiducia Together · Next review due 2027-08-28
Please note: This page explains a word or a process in education. It is general information about the system, the law and the guidance in England — not advice about your child, your school or your exam. If a decision is going against you, get advice from one of the free services we link to before you agree to anything or miss a deadline. If you are revising, check your own exam board's specification: boards word things differently and yours is the one that marks you.