Tiny particles on the move
Scientists picture matter as made of particles that are too small to see, and they draw them as dots. In a solid the particles are packed close together in a fixed pattern. They cannot move around, but they vibrate in place. That is why a solid keeps its shape. In a liquid the particles are also close, but they are not in a fixed pattern. They slide past one another, so a liquid flows and takes the shape of its container. In a gas the particles are far apart and move quickly in all directions, so a gas spreads out to fill all the space it has. When matter is heated, its particles move more. When it is cooled, they move less. Remember that the drawings are a model, not photographs.
| State | Particles are… | They… |
|---|---|---|
| solid | packed, in a pattern | vibrate in place |
| liquid | close, no pattern | slide past each other |
| gas | far apart | move fast everywhere |
Human particles (a grown-up helps). In a clear space, stand shoulder to shoulder and sway a little: you are a solid. Loosen up and shuffle past each other while staying close: a liquid. Then spread out and walk quickly in all directions without bumping: a gas. Draw each state with dots and write one sentence about it.