The Earth, its atmosphere and the oceans are made from substances in different states. The particle model describes the arrangement, movement and energy of particles in a substance. The model explains the physical properties of substances in the solid, liquid and gas state.
Use the particle model to explain why an iceberg has a fixed shape.
An iceberg is in the solid state. It has a fixed shape because the particles (water molecules) are arranged in fixed positions.
Use the particle model to explain why water from a river can change shape when filling a container.
Water is in the liquid state. It can flow because its particles can change position and slide past each other.
Use the particle model to explain why air can fill a room.
Air is in the gas state. It fills a room because the particles are far apart and are free to move position.