AQA Physics 9-1 Particle model of matter

Density = mass / volume

• Spacing
• Order
• Movement

Vibrate

• a) touching
• b) close together, mostly touching
• c) far apart

• Kinetic energy
• Potential energy

Potential energy

Sublimation

Melting

Kinetic energy

Condensation

The energy required to melt 1kg of a substance without a change in temperature.

(It is the same as the energy released when 1kg of a substance freezes)

1. Particles are constantly moving randomly

2. Particles collide with each other and the walls of the container without losing any kinetic energy

3. The temperature of the gas is related to the average kinetic energy of the particles

4. As the kinetic energy of the particles increases, the temperature increases

• Gas particles collide with the walls of their container.
• As they change direction, they exert a force on the wall (at right angles to it).
• Gas pressure is the sum of all these forces divided by the total surface area of the container walls.

Higher temperature means higher average kinetic energy of the gas particles.

Particles therefore collide with the container walls more often and with greater force

If pressure goes up by Z times, the volume goes down by Z times (and vice-versa)

• If the volume of a gas is reduced,
• - the particles hit the walls of the container more often thereby increasing the force
• - the collisions are spread over a smaller surface area

Both of these changes increase the pressure as 

When a piston is pushed to compress a gas a force must be used to push the piston through a distance.

• Since Work = force x distance, 
• work has been done on the gas. This increases the internal of the gas and increases temperature.