# States of matter

Solids, liquids and gases are three ways particles can be arranged. In a solid they are packed and vibrate. In a liquid they slide past each other. In a gas they move freely and far apart.

Physics (school) · Part 04: Particles and heat · Card 2 of 8 · Last updated 2026-10-19

## Analogy

A solid is a seated crowd. A liquid is a crowd shuffling through a hall. A gas is people running around a field.

## In practice

Ice, water and steam are the same substance in three states.

## Practice

### Flashcards

- **Describe the particles in a gas.** Far apart, moving fast in random directions.

## Questions people ask

### Why can you pour a liquid but not a solid?

In a liquid the particles are close but not locked in place, so they slide past each other and the liquid flows to take the shape of its container. In a solid the particles are held in fixed positions and can only vibrate, so the solid keeps its own shape.

### Why can gases be squashed but liquids cannot?

In a gas the particles are far apart with lots of empty space, so pushing them closer is easy. In a liquid they are already almost touching, so there is very little space left to squeeze into. This is why hydraulic brakes use liquid to pass force along.

## Related concepts

- [Density](https://studyvisually.com/learn/science/physics-school/physics-school-part-4/physics-school-part-4-concept-1)
- [Changes of state](https://studyvisually.com/learn/science/physics-school/physics-school-part-4/physics-school-part-4-concept-3)
- [Gas pressure](https://studyvisually.com/learn/science/physics-school/physics-school-part-4/physics-school-part-4-concept-8)

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