This how it works covers How Density Links to Particle Model within Density for GCSE Physics. Revise Density in Particle Model for GCSE Physics with 13 exam-style questions and 30 flashcards. This topic shows up very often in GCSE exams, so students should be able to explain it clearly, not just recognise the term. It is section 6 of 13 in this topic. Use this how it works to connect the idea to the wider topic before moving on to questions and flashcards.
⚙️ How Density Links to Particle Model
At the particle level, the three states of matter have very different densities because of packing:
- Solids: Particles are closely packed in a regular lattice — very little empty space, so density is high.
- Liquids: Particles are still close together but disordered — density similar to solids but slightly lower (water is an exception — it expands on freezing).
- Gases: Particles are widely spaced (typically 10× further apart than in solids) — density is about 1000× lower than the equivalent liquid or solid.
This explains why the density of steam (0.0006 g/cm³) is so much lower than liquid water (1.0 g/cm³) — the same molecules, just with enormous gaps between them.
Practice questions for Density
What is the correct equation for density?
Explain why gases have a much lower density than solids, using ideas about particles.