Chemistry · Grades 4–7
Particles, states and changes · Revision sheet
Use particle models without treating the spaces between particles as air.
Learn the idea
Particle model
A model represents matter as particles. Heating can change their motion and separation without enlarging the particles themselves.
States
Solids retain shape, liquids flow with a nearly fixed volume, and gases spread through an available container.
Changes
Melting changes arrangement, not the chemical identity of a pure substance.
Limits
Diagrams exaggerate sizes and spacing; they are models, not photographs.
Explain without looking
- In a sealed rigid container, does a gas gain mass merely because it is heated?
- Describe one limitation of a drawing made of identical circular particles.
Further reading and review references
These are reference links, not copied exercises, institutional endorsement or proof of independent review.
Independent educational review required. Grade bands are approximate; these are not officially aligned curricula.