Particle Model

• The three states of matter are solid, liquid and gas. Melting and freezing take place at the melting point, boiling and condensing take place at the boiling point
• The three states of matter can be represented by a simple model. In this model, particles are represented by small solid spheres. Particle theory can help to explain melting, boiling, freezing and condensing.
• (HT only) Limitations of the simple model include that there are no forces between the spheres, and that atoms, molecules and ions are not solid spheres.