Channel 4 Learning

Science Essentials logo
Choose Life Material World Get Physical
What's the big idea
Activities for home
For Teachers
Image bank
Web links

What's the big idea?

Can you imagine iron gas? It is a possibility. Gases are one of the three states of matter, along with solids and liquids. Materials can exist in these three states - but we usually only see one or two. We know that iron is a hard, heavy solid metal - and can also be a runny liquid. But we see water in three different states - solid, liquid and gas.

Gases around us The tiny particles of a gas are free to move in all directions

Solid water is called ice; liquid water is familiar; and there is water gas - or steam. A gas has weight, but no shape - and it fills the space around it. So steam quickly fills your bathroom.

(Actually, if you want to be absolutely correct, the stuff that fills your bathroom is water vapour - droplets of water in the air. Real steam is invisible - it's boiling hot - and you can't see this water gas.)

Gases spread into the space around them.Air freshener in a room can be smelled everywhere.Oxygen is gas. So is carbon dioxide - the bubbles in fizzy drinks. Gases around us