Particle Model of Matter P1T3

Change in Thermal Energy

The product of the mass, specific heat capacity and temperature change of a substance.

Chemical Changes

Changes to the chemical structure of a substance. The substance does not usually restore its original properties when the changes are reversed.

Condensation

The changing from vapour state to a liquid state, when a substance is cooled.

Density

The mass per unit volume of an object.

Evaporation

The changing from liquid state to a vapour state, when a substance is heated.

Freezing

The changing from a liquid state to a solid state, when a substance is cooled.

Gas Temperature

The temperature of a gas is directly proportional to the average kinetic energy of its molecules.

Internal Energy

The energy stored by the atoms and molecules that make up a system. It is equal to the sum of the total kinetic and potential energies of the particles in the system.

Latent Heat

The energy required for a substance to change state.

Melting

The changing from solid state to liquid state, when a substance is heated.

Pascals

The unit of pressure, equal to a force of one Newton acting perpendicular to an area of one metre squared.

Physical Changes

Changes to the physical properties of a substance which can be reversed. Changes of state are physical changes since substances can restore their original properties when the changes are reversed.

Pressure

The force acting perpendicular to a surface, per unit area.

Specific Heat Capacity

The amount of energy needed to increase the temperature of one kilogram of a given substance by one degree Celsius.

Specific Latent Heat of Fusion

The amount of energy needed to change the state of one kilogram of a substance from solid state to liquid state, whilst held at constant temperature.

Specific Latent Heat of Vaporisation

The amount of energy needed to change the state of one kilogram of a substance from liquid state to vapour state, whilst held at constant temperature.

Specific Latent Heat

The amount of energy needed to change the state of one kilogram of a substance, whilst held at constant temperature.

Sublimation

The direct changing of a substance from a solid state to a vapour state, without passing through the liquid phase.