KS3 Physics

Energy
Motion and Forces
Waves
Electricity and Electromagnetism
Matter
Space Physics

States of Matter

Everything is made up of tiny particles. The state of a material depends on the strength of the forces of attraction between its particles.

When looking at objects around us, we can see that different objects are in different states of matter. The Particle Theory Model explains the unique properties of the different states of matter.

The three states of matter are solidsliquids and gases. Let’s look at how particles are arranged in each state of matter, as well as their properties.

Solids

The diagram below represents the arrangement of particles in a solid.

As shown, the particles are very close together causing them to be arranged in a regular lattice shape. The particles are close together due to the strong forces between them.

Solids maintain a fixed shape because their particles are unable to move around freely. Under certain conditions, such as when heated, the particles can vibrate around fixed positions.

Example

• Ice cubes are in a solid state

Liquids

The diagram below represents the arrangement of particles in a liquid.

In liquids, particles are arranged randomly. This is because the forces between them are weak. Having said this, some of the particles are still close together.

Liquids take the shape of their containers because they can flow.Liquid particles are constantly in random motion. Similar to solids, when heated, the particles vibrate more.

Example

• Water is in a liquid state

Gases

The diagram below represents the arrangement of particles in a gas.

In gases, the forces between particles are very weak, allowing them to move around freely. As you can see in the diagram above, the particles are very far apart from each other. Gases always take the shape of their containers, as they have no definite shape.

When the temperature increases, gas particles move faster.

Example

• Water vapour is in a gaseous state

Comparing the States of Matter

Below is a table that compares the three states of matter.

Quizzes