Matter can be a solid, a liquid or a gas. A solid keeps its own shape, like a stone or an ice cube. A liquid flows and takes the shape of its container, like water or juice. A gas spreads out to fill any space, like the air in a balloon.
Heating and cooling can change a material. Ice melts into water when it warms up, and water freezes into ice when it gets very cold. Chocolate melts in your hand and goes hard again in the fridge: that change can be turned back. Some changes cannot be turned back. When you bake a cake or burn paper, you cannot get the egg, flour or paper back.
Worked example
Is melting butter a change that can be turned back?
- Melted butter is a liquid.
- If we cool it in the fridge it becomes solid again.
Answer:So yes, melting butter can be turned back.
Key words
- solid
- keeps its shape
- liquid
- flows and takes the shape of its container
- gas
- spreads out to fill a space
- melt
- change from solid to liquid when heated
- freeze
- change from liquid to solid when cooled
Practise this
New questions every time.
NGSS-referenced: 2-PS1-4