1.2 States of matter
Summary: Do you like ice in cold drinks? Ice cubes are made up of water particles. Ice is water in the solid state. Now imagine a steaming pan. Steam is also made up of water particles. It is water in the gas… Tags: science oxford-science student-book-7 chemistry Created: 2026-05-19 Last Updated: 2026-05-19
After this topic, you will be able to:
- compare the properties of a substance in its three states
- describe the particles in the three states of matter
- use the particle model to explain the properties of a substance in its three states.
Think back
- What is the particle model?
- How many types of particle are in a single substance?
- What is a property in science?
Key idea Most substances can exist in three states: as a solid, a liquid, or a gas. In each state of matter, the particles are the same, but their arrangement, movement, and separation are different.
Key words solid, liquid, gas, states of matter
Do you like ice in cold drinks? Ice cubes are made up of water particles. Ice is water in the solid state. Now imagine a steaming pan. Steam is also made up of water particles. It is water in the gas state.
What are the states of matter?
Water can exist in three states: as a solid, a liquid, or a gas. These are the states of matter. In each of the three states, the water particles are identical (the same). But the properties of ice, liquid water, and steam are different. These pages explain why.
A Give the state of water when it is steam.
How does state affect the properties of a substance?
Most substances can exist in three states. The state of a substance depends on its temperature. At room temperature, gold is solid. But if you make it hot enough, gold exists as a liquid or gas. Table 1 compares the properties of a substance in its three states. Table 1 A comparison of the properties of a substance in its three states. State
Can you compress the substance in this state?
Does the substance flow in this state?
Shape
solid
no
no
fixed, unless you apply a force
liquid
no
yes
takes the shape of the bottom of its container
gas
yes, a lot
yes
takes the shape of the whole container
B Describe two differences between the properties of a substance in the solid and liquid states.
How can particles explain properties?
The particles of a substance do not change. Water particles are the same in all three states. But the arrangement and movement of the particles - and how strongly they hold together - are different in each state.
Figure 1 shows particles of a substance in the solid state. When a substance is in the solid state, its particles touch their neighbours. This explains why you cannot compress it (press it into a smaller shape). In the solid state, particles are arranged in a pattern. This explains why crystals have straight edges and smooth faces.
Figure 1The arrangement of particles in a solid substance.
When a substance is in the solid state, its particles do not move around. Instead, they vibrate (shake) on the spot. This explains why solids have a fixed shape and why they cannot flow.
Figure 2 shows particles of a substance in the liquid state. When a substance is in the liquid state, its particles touch their neighbours. This explains why you cannot compress it. The particles move in different directions from place to place, moving over each other. This explains why liquids flow and why they have no fixed shape.
Figure 2The arrangement of particles in a liquid substance.
Figure 3 shows particles of a substance in the gas state. When a substance is in the gas state, its particles spread out until they are far apart. This explains why it is easy to compress a gas. The particles move quickly and in different directions, everywhere in the container. This explains why gases flow.
Figure 3The arrangement of particles in a gas substance.
C Explain why you can compress a substance in the gas state, but not in the solid or liquid states.
Maths skills In 2015, a Japanese train set a world record. It reached a Speed of 603 km/h (0.168 km/s). In the air, oxygen particles travel at about 500 m/s. Calculate which is faster - the train or the particles. Hint: 1 km/s is the same as 1000 m/s. You can start by changing the speed of the train from km/s to m/s.
Stretch zone
- Copy and complete the sentences. In the solid state, the shape of a substance is blankIn the liquid state, a substance cannot be blankIn the gas state, a substance can be compressed a blankA gas takes the shape of its blank
- Use the particle model to explain why: a substance has no fixed shape in the liquid statea substance cannot flow in the solid statea substance can be compressed in the gas state.
Stretch zone
- Compare three properties of a substance in the solid and gas states.