Solid, Liquid, Gas Basics

Your book, the juice in your glass, the air you are breathing right now — all of these are matter. Matter is anything that takes up space. Scientists sort all matter into three groups called the states of matter.

Solid — keeps its shape

• A solid has a fixed shape and size — it does not change shape on its own.
• You can hold it, pick it up, and put it down and it stays the same shape.
• Examples: rock, wood, ice, book, pencil, brick.
• Example: An ice cube keeps its square shape until it melts.

Liquid — takes the shape of its container

• A liquid does not have a fixed shape — it flows and takes the shape of whatever container it is poured into.
• A liquid does have a fixed volume (amount) — pouring it does not change how much there is.
• Examples: water, juice, milk, honey, oil, melted chocolate.

Gas — spreads to fill any space

• A gas has no fixed shape or volume — it spreads out to fill whatever container it is in.
• Most gases are invisible, but they are real — air is a mixture of gases.
• Examples: air, steam, the gas inside a balloon, smoke.

Tricky examples

• Ice is solid water. When it melts it becomes liquid water. When water boils it becomes steam — a gas.
• Sand looks like it flows, but each grain is a tiny solid. Sand is still a solid.