a scientific model using the idea of moving particles to explain the behaviour of matter

caused by a force acting over an area on a surface; it can be calculated using: pressure = force ÷ area

Changes of pressure

Combined science

Calculating density and measuring volume

Measuring density

Pressure in a fluid

Upthrust

Explaining convection

In the Energy of moving particles unit, they will build on this knowledge to learn how the movement and nature of different particles transfers energy by conduction, and how specific heat capacity and specific latent heat quantify the effect of heating on the properties of a material.

In the Heating and cooling unit, pupils learnt how the motion of particles in solids, liquids and gases changes when they are heated, how thermal conduction and insulation work and why heating different materials doesn’t always increase their temperatures by the same amount. 

This unit defines density and explores how it varies between states of matter based on atomic arrangement. It covers mass conservation during physical changes, gas behaviour, fluid pressure, buoyancy, and atmospheric pressure, and calculations involving density, mass, and volume relationships.

Particle explanations of density and pressure

It can be used to explain how matter behaves.

It can be used to predict how matter will behave.

The model is made of diagrams or animations.

It says that particles move in liquids and gases but not in solids.

It says that particles in solids, liquids and gases are always moving.

Which of the following statements about the particle model are correct?

The mass of the gas in the container increases.

The volume of the gas in the container increases.

The pressure of the gas on the container increases.

The gas exerts a greater average force on the inside of the container.

There are more collisions per second between gas particles and container.

A sealed container of fixed volume contains gas. Which of the following happen when more gas is added to the container?

There are more particles inside, so their collisions become more frequent.

This increases the outward forces exerted by the air on the balloon.

The outward forces are now greater than the inward forces.

This makes the balloon expand, which increases the volume inside it.

The particles inside are now more spread out, so collisions are less frequent.

This decreases the pressure on the inside of the balloon.

Expansion stops when this balances the air pressure outside.

A child blows air into a balloon. Order the statements to describe and explain what happens.

The tyre wears out unevenly and more quickly.

There is less contact area between the tyre and road surface.

Which of the following happen when a car tyre is under-inflated, so that there less air in it than when it is correctly inflated?

The pressure inside the tyres stays the same.

The mass of air inside the tyres increases.

The mass of air inside the tyres stays the same.

A driver puts air into their car’s tyres when the car is empty. They check that the pressure is correct. If a lot of heavy luggage is now put into the car, which of the following are correct?

increasing the temperature of the gas inside

decreasing the temperature of the gas inside

Which of the following changes would increase the pressure of a gas in a closed container?

Which of the following can be used to describe the motion of particles in a gas?

Which of the following show a definition of pressure or a unit of pressure?

Which of the following are equal to 1 kN?

Particles collide with each other more often.

The particles are squashed so they become smaller.

The particles repel each other more strongly all the time.

If the particles in a gas are pushed closer together, the pressure of the gas increases. Which of the following explains why?

A table of weight 500 N stands on the floor. The area of contact between the table and the floor is 200 cm$$^2$$. The pressure exerted by the table on the floor is __________ N/cm$$^2$$.

pressure of gas = force on one inner face of cube ÷ area of one face

pressure of gas = force on one inner face of cube ÷ total area of all faces

The gas exerts pressure because its weight pushes down on the container’s base.

The gas exerts pressure because its particles exert forces on all inner faces.

A sealed container in the shape of a cube contains gas. Which of the following statements are correct?

Starter Quiz

Which of the following can be used to describe the motion of particles in a gas?