British Sign Language Glossaries of Curriculum Terms

BSL Environmental Science Glossary - Particle model definition

Definition: All materials are made of tiny particles. The particle model describes the arrangement and movement of particles in a substance. There is space between the particles, and they are always moving. When you increase the temperature, the distance between the particles will increase, which means the particles can move around each other.

I will use ice cubes as an example. The ice cube is a solid with a fixed shape. The particles are closely packed but moving slightly. The ice cube will change into water (liquid form) when the temperature increases. The particles are moving faster with more space in between, which is why water flows. It is not a fixed shape but with a fixed volume. With further increase in the temperature, water will become steam. More space exists between the particles, and they move fast in random directions.