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States of matter
Beginner
Solid, liquid, gas and plasma differ in order and freedom.
Solids keep shape and volume, liquids keep volume but flow, gases fill containers, plasmas are ionised gases. The state depends on how strongly particles attract compared with their thermal energy.
Water changes among ice, liquid and steam with temperature.
Glass and some plastics are amorphous solids, not true liquids.
In more detail
Matter exists as solids, liquids, gases and plasmas. Solids keep their shape, liquids keep their volume but take the shape of their container, and gases fill any container.
Real-world uses
- Refrigerators rely on changes between liquid and gas states to move heat.
- Plasma TVs and fluorescent lamps use ionised gases, which are a fourth state of matter.
- Engineers choose materials and temperatures for cooling systems by knowing whether a substance will be a liquid, a gas or a solid under the working conditions.
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Frequently asked questions
Are liquids and gases both fluids?
Yes. A fluid is any substance that flows and takes the shape of its container.
What is a plasma?
A gas heated enough that electrons separate from atoms, forming charged particles.
What makes a gas different from a liquid?
Gas particles are far apart and move freely, while liquid particles stay close together but can slide past each other.