The Three States of Matter
Everything around you is made of matter. In this lesson you will learn the three everyday states of matter and why they behave so differently.
What you will learn
- Name the three states of matter: solid, liquid, and gas
- Describe how the tiny particles sit in each state
- Give an everyday example of each state
- Explain in simple words what happens when matter changes state
Key words
- Matter
- — anything that takes up space and has weight
- Particle
- — a tiny piece of matter, far too small to see
- State
- — the form matter takes: solid, liquid, or gas
Three states of matter
Look around you. A book, the water in a glass, the air you breathe — they are all matter. But they do not behave the same way. That is because matter comes in three everyday states: solid, liquid, and gas.
A solid keeps its own shape, like a rock or a chair. A liquid flows and takes the shape of its container, like water or juice. A gas spreads out to fill all the space it can, like the air in a balloon.
How the tiny particles behave
All matter is made of particles that are far too small to see. What makes the three states different is how those particles sit and move.
In a solid, the particles are packed close together and only shake in place — so a solid keeps its shape. In a liquid, the particles still touch but can slide past each other — so a liquid can flow. In a gas, the particles are far apart and move quickly in every direction — so a gas spreads out.
Changing from one state to another
Matter can change from one state to another. Heating usually moves it toward gas; cooling usually moves it toward solid.
Think of water. Cool it down and it freezes into ice — a solid. Warm the ice and it melts back into liquid water. Heat the water more and it boils into steam — a gas. It is the same water all along; only its state changes.
Everyday example
Maryam leaves an ice cube on a plate on a warm day. Soon there is a small pool of water. The cold has not disappeared — the ice has melted from a solid into a liquid.
Practice
1. Which of these is a gas?
2. When an ice cube melts, what happens?
3. Why can a liquid flow, but a solid cannot? Use the word "particles"in your answer.