Everything around you is made of matter. Matter exists in three main states; solids, liquids and gases.

Materials can be changed from one state to another by heating or cooling.

Matter is made from tiny particles which are too small to see. These particles are arranged differently in different states of matter.

Solids, Liquids and Gases

Solids, Liquids and Gases

Solids, Liquids and Gases

Solids, Liquids and Gases

Brick

Paper

SandChocolate Juice

Petrol

Water

Olive Oil

Air

Water Vapour

Helium (inside the balloon)

Natural gas (which is mostly

methane)

Solids

Heating a solid can turn it into a liquid. This process is called melting.

SOLID LIQUID GAS

Solids can be held.

The volume of a solid remains constant (it doesn’t change).

Solids hold their shape (although they can be cut or broken and some can be squeezed or stretched).

In a solid, the particles are packed together tightly so they cannot move.

The properties of solids make them suitable for different uses. For example, rubber is naturally bouncy and so is a good material for making balls. Fabric is flexible and so a good choice for making clothes and soft furnishings. Bricks are made so that they are strong and suitable for building.Solids

A rubber ball. Fabric shirts. A brick wall.

Some solids can behave more like a liquid. For example, salt or flour can be poured like a liquid but they are made up of tiny solids.

Salt being poured onto

a spoon.

LiquidsSOLID LIQUID GAS

Particles move around in a liquid at a constant distance from each other.

Liquids change shape to fit the container they are in.

If a liquid is not in a container, it forms a puddle.

The volume of a liquid remains constant.

Liquids flow easily and are difficult to hold if they are not inside a container.

Cooling a liquid can turn it into a solid. This is known as freezing.

Heating a liquid can turn it into a gas. This is called evaporation.

Liquids have different viscosity, which means how easily they flow. Water has low viscosity, and flows very easily. A liquid like tomato ketchup has a much higher viscosity and flows much more slowly.

LiquidsCommon liquids include water, oil, milk, petrol and blood.

Water Milk

Olive Oil

Petrol

Blood

In cooking, ingredients like chocolate are often heated to become liquids and then change back into solids when they cool again. Chocolate crispy cakes are a good example of this.

Water Ketchup

GasesSOLID LIQUID GAS

Because the distance between the particles in a gas can change, the volume of a gas can change depending on how much space it has to spread out.

Gases do not keep their shape. They spread out to fill a container.

Gases can also be squashed into a smaller space.

Gases are lighter than liquids, and float up through them. Pockets of gas in a liquid are known as bubbles.

Cooling a gas can turn it into a liquid. This is called condensation.

Gases

Gases have different weights. Helium is used to fill party balloons because it is lighter than air and so the balloon floats.

Gases are often invisible. For example, we cannot see air which is made up of a mixture of gases; it is mostly nitrogen (78%), with 21% oxygen and small amounts of argon and carbon dioxide. Other gases have a colour and can be seen. For example, chlorine gas is a greeny yellow colour.

The gas that is used for cooking and heating at home is mostly methane. When it is lit, it burns with a stable flame that can be used to run boilers or to cook with.

Helium can be found inside

these balloons.

The gases in the air are blowing this dandelion

seed head.

Gases being used for cooking.

Changing StatesMatter can change from one state to another by heating or cooling.

When matter changes states, the particles do not change, but the way that they are arranged and move around does.

When it is cooled, water vapourcondenses into a liquid. This is why water droplets form on a window or mirror if you breathe on it.

Melting Evaporation

CondensationFreezing

Water becomes a solid at 0ºC. Below this temperature it is ice, and the particles are arranged in a fixed pattern.

Between 0ºC and 100ºC, water is a liquid. The atoms can move around.

Over 100ºC, water becomes water vapour, which is a gas. The atoms can move further apart. When a kettle boils, you can see the water vapour escaping through the spout.

The water cycle works because of the way in which water changes state.

Different materials change states at different temperatures. This is why some materials are gases at room temperature (e.g. air), some are liquid (e.g. water) and some are solid (e.g. paper).

Changing StatesNot all materials can change from one state to another.For example, if you heat wood it will burn, rather than melt.

There is a fourth state of matter, known as plasma. Gases can turn into plasma when matter gets so hot that the atoms break apart. Stars are mostly made of plasma. On Earth, lightning is also a good example of natural plasma. Man-made plasma is used in TV screens.

Caption

Separating matter

A sieve can be used to separate solids. Because a solid cannot change its shape, larger pieces cannot go through the holes.

Evaporation and condensation can be used to remove solids from a liquid. When the dirty water is heated, evaporation occurs and the solids are left behind. The water vapour can be trapped and cooled to give clean water.

We can use our knowledge of solids, liquids and gases to separate matter.

When a liquid is filtered, any solid matter is left behind on the filter, while the liquid flows through.

Dirty water

This filter cleans dirty water in a

fish tank.

Using a sieve to filter composted earth.