Topic overview

Start with the big picture

A state of matter reflects how particles are arranged and move. Solids have a fixed structure and shape; liquids retain volume but take the shape of their container; gases expand to fill available space and are highly compressible. Plasma and Bose–Einstein condensates extend this picture. Intermolecular forces help determine states and transitions, while melting, boiling and other phase changes involve energy transfer that can occur without a temperature change. Phase diagrams show stable regions and key points such as the triple and critical points. The topic also introduces ideal and real gas behavior, surface tension, viscosity, diffusion and special transitions such as sublimation. These ideas provide a foundation for understanding physical properties and their relevance to pharmacy.