States of Matter

Solid:

- Particles touching in a regular arrangement.
- Particles vibrate in fixed positions with strong forces between them.
- Low energy
- Constant shape and volume.

Liquid:

- Particles touching in a random arrangement.
- Particles move around each other with weak forces between them.
- Moderate energy.
- Fixed volume but not shape, takes the shape of the container.

Gas:

- The particles are far apart in a random arrangement.
- Particles move around freely with weak forces between them.
- High energy
- No fixed volume or shape.

Changes in State

What Happens to Particles?

- Solids have particles closely packed and are in a regular arrangement.
- When heated, the particles vibrate (gain kinetic energy), and at first, they have a small amount more energy.
- The particles gain kinetic energy when heated, breaking the forces between them to form a liquid.

- Liquid particles touch each other and are arranged randomly.
- They move around each other with moderate energy.
- When boiled or evaporated, the particles move faster and gain more kinetic energy until the forces between them are overcome to form a gas.

- The arrangement of the gases is random, far apart, and does not touch.
- They move around freely with lots of energy.

Curves: Heating and Cooling

- The horizontal regions (plateaus) in the heating curve occur when the heat energy is used to break the forces between the particles instead of increasing the temperature.
- Instead of lowering the temperature, the loss of heat causes the substance to condense or solidify, creating the horizontal regions.