Ice, water and steam are all the same stuff: water. They are three states of matter.
| State | Shape | Amount (volume) | Particles |
|---|---|---|---|
| Solid | Keeps its own shape | Stays the same | Packed tight, wiggle in place |
| Liquid | Takes the shape of its container | Stays the same | Close, slide past each other |
| Gas | Fills any container | Spreads out to fill it | Far apart, zoom around |
Key idea
A solid keeps its shape. A liquid flows and takes the shape of its container. A gas spreads out to fill the whole space it is in.
Worked example: Sand: solid or liquid?
You can pour sand from a bucket. Is sand a liquid?
- Look at one grain with a hand lens.
- Each grain keeps its own shape, and it does not flow on its own when you tip it a little.
Answer: Sand is a solid, made of many tiny solid grains.
Common mistake
Thinking anything that pours is a liquid. Sugar, salt and sand pour because they are many small solid pieces.
Try it at home
- Pour the same amount of water into a tall glass, a bowl and a plate.
- Does the water change shape? Does the amount change? (Pour each back into a measuring cup to check.)
Going further. In Gas in a Box you can watch gas particles bounce around and push on the walls.