Solid, Liquid or Gas

Water is the only common substance that is naturally found as a solid, liquid or gas. 

Solids, liquids and gases are known as states of matter. 

What is matter?

Matter is everything around us.

Scientists use the word matter to describe anything that takes up space and has mass (weight).

Matter is made up of tiny particles, including;

• atoms
• and groups of atoms called molecules.

Atoms are like individual LEGO blocks. They are the smallest unit that anything can be easily broken down into. If atoms are like LEGO blocks, molecules are what you can build with them. 

The way atoms and molecules move affects the state the matter is in.

Solid

Right now, you might be sitting on a chair at a desk, or standing on the floor. The chair, desk and floor are all solids. A solid is something that can hold its own shape and is hard to squash. 

The particles in most solids are closely packed together and do not move around.

Ice is water in its solid form or state. Ice keeps its shape when frozen. Ice is different from most solids because its molecules are not packed as closely together as they are in liquid water. This means ice takes up a little more space than the same amount of liquid water. This is why ice floats. It is also why old pipes can crack and burst when the water inside them freezes.

Liquid

A liquid can be poured and will take on the shape of the container that it is poured into. 

If you have a glass of water and pour it into another glass, it takes on the shape of the glass. If you spill the water, it will go everywhere, because it isn’t in a container.

Except for water, most liquids have particles which take up more space than they do when they are in their solid state. The particles in liquids can move around and slide past each other. 

What examples of liquids can you come up with?

Gas

The atoms and molecules in gases are much more spread out than in solids or liquids. They move freely at high speeds. A gas will fill any container, but if the container is not sealed, the gas will escape. Gas can be squashed much more easily than a liquid or solid.

Right now, you are breathing in air – a mixture of gases.

Water vapour is water as a gas. Unlike ice or water, water vapour cannot be seen. We cannot see the water vapour we breathe out, but if we hold our glass or a smartphone to our mouths, we can see the water vapour condensing (becoming liquid) on these objects as it cools.

Can you find out if there are any other states of matter?