States of Matter and Their Properties

The Three States

• Solid: particles are closely packed and vibrate in fixed positions. Fixed shape and volume.
• Liquid: particles are close but can move around. Fixed volume but takes the shape of the container.
• Gas: particles are far apart and move freely. No fixed shape or volume.

Changes of State

• Melting: solid to liquid.
• Freezing: liquid to solid.
• Evaporation / Boiling: liquid to gas.
• Condensation: gas to liquid.
• Sublimation: solid directly to gas.

Key Points

Heating gives particles more energy so they move faster and spread apart. Cooling does the opposite. The mass stays the same during a change of state.