States Of Matter: Solid, Liquid, Gas

Science Interactive lesson Free to play

States of matter are the physical forms that a substance can take — the three most common being solid, liquid, and gas. Everything around us, from an eraser to a glass of water to the air we breathe, is made of tiny particles, and it is how those particles are arranged and how fast they move that decides which state something is in.

In a solid, particles are packed tightly in fixed positions, so a solid keeps its own shape and volume — a LEGO brick stays a brick wherever you put it. In a liquid, particles are still close together but can slide past one another, so a liquid flows and takes the shape of its container while keeping the same volume. In a gas, particles are far apart and move quickly in every direction, so a gas spreads out to fill all the space available.

A key idea is that the same substance can change state by gaining or losing heat: adding heat makes particles move faster and spread out (melting, then boiling), while cooling slows them down and packs them closer (condensing, then freezing). Water, for example, can be ice, liquid water, or steam.

▶ Play the lesson — free, no signup

Want to create your own Spark? Sign up free — type any skill and LearnBuddy builds you a playable lesson.

Sign up free to create your own Spark

What this Spark covers

Frequently asked questions

What are the three states of matter?
The three common states are solid, liquid, and gas. A solid holds its own shape, a liquid flows and takes the shape of its container, and a gas spreads out to fill all the space it can.
Why does a solid keep its shape but a liquid does not?
In a solid the particles are packed tightly in fixed positions and can only wiggle, so the shape stays fixed. In a liquid the particles are still close but can slide past each other, so the liquid flows and takes the shape of whatever container it is in.
How does water change from one state to another?
Adding heat makes water's particles move faster: ice melts into liquid water, and liquid water boils into steam (a gas). Taking heat away does the reverse — steam condenses back to water, and water freezes into ice.
Why can we smell food from across the room?
Smells travel as a gas. Gas particles are far apart and move very fast in every direction, so they spread out and drift across the room until they reach your nose.
Is air a solid, liquid, or gas?
Air is a gas. It has no fixed shape, fills any space it is in, and its particles are far apart and move quickly — all the signs of the gas state.

More Sparks like this

Loved this Spark? Sign up free for AskBuddy AI tutoring, past-year papers, and unlimited Sparks.

Sign up free →