Physics Particle Model Of Matter

What is density?

How much mass is in a given volume.

Describe the particle arrangement and movement in a solid.

Particles are tightly packed in a fixed regular pattern.

They vibrate about fixed positions but do not move freely.

Strong forces of attraction holds them together.

How do particles behave in a liquid?

Particles are close together but arranged randomly.

They can flow and move past each other.

Weaker forces of attraction than in solids.

What are the characteristics of particles in a gas?

Particles are far apart and move randomly at high speeds.

No force of attraction between them.

They collide with each other and container walls, exerting pressure.

What is internal energy?

The total kinetic energy and potential energy of all particles in a substance.

What happens to internal energy when a substance is heated?

Kinetic energy increases, so particles move faster.

In solids and liquids, potential energy increases as bonds weaken.

Define specific heat capacity.

The amount of energy required to raise the temperature of 1kg of a substance by 1°C.

Define specific latent heat.

The energy required to change the state of 1kg of a substance without changing its temperature.

What are the two types of specific latent heat?

Specific latent heat of fusion - Energy needed to change solid into liquid.

Specific latent heat of vaporisation - Energy needed to change liquid into gas.

Why does temperature remain constant during a change of state?

The energy is used to break or form bonds, not to increase kinetic energy.

What causes gas pressure?

Collisions of gas particles with container walls.

The faster the particles move, the greater the pressure.

What happens to gas pressure when temperature increases?

Higher temperature - higher kinetic energy - more frequent and forceful collisions - increased pressure.

What is Boyle’s law?

Pressure and volume are inversely proportional for a fixed mass of gas at constant temperature.

How does doing work on a gas affect its temperature?

Compression increases gas temperature because energy is transferred to particles making them move faster.

How do changes in volume affect gas pressure?

Decreasing volume - increased collisions - higher pressure.

Increasing volume - fewer collisions - lower pressure.

What happens when a gas expands rapidly?

It cools down because energy is spread out over a large volume.

How does atmospheric pressure change with altitude?

Higher altitude - fewer air molecules - lower atmospheric pressure.