The States of Matter: Solid, Liquid, Gas (and Plasma)
Everything around you is made of tiny particles. Whether something is a solid, liquid, or gas comes down to how much energy those particles have and how tightly they are held together.
The three everyday states
The difference is all about particle arrangement and movement.
- •Solid: particles packed tightly in a fixed pattern, vibrating in place. Fixed shape and volume.
- •Liquid: particles close but free to move past each other. Fixed volume, takes the shape of its container.
- •Gas: particles far apart, moving fast in all directions. No fixed shape or volume — it fills its container.
Changing state
Adding energy (heat) moves matter from solid → liquid → gas: melting, then boiling/evaporating. Removing energy reverses it: condensing, then freezing. The particles do not change — only their energy and arrangement do.
The fourth state: plasma
Heat a gas enough and its particles break apart into charged pieces, forming plasma. It is the most common state in the universe — stars, including our sun, are made of it.
Frequently asked questions
What happens to particles when a solid melts?
They gain energy, vibrate more, and break free of their fixed positions so they can slide past each other — becoming a liquid.
Is plasma a real state of matter?
Yes — it is a gas whose particles have been given so much energy they become charged (ionised). Stars and lightning are plasma.