Solid vs. Liquid: What's the Difference?
Both have a fixed volume, but they differ in shape and how their particles move. In a solid, particles are packed tightly and locked in place, so it holds a fixed shape. In a liquid, particles are still close together but can slide past each other, so it flows and takes the shape of its container. Heat a solid enough and it melts into a liquid.
See the difference, explained visually.
Watch a 2-minute animated lesson comparing solid and liquid.
At a glance
| Solid | Liquid | |
|---|---|---|
| Shape | Fixed | Takes its container's shape |
| Volume | Fixed | Fixed |
| Particles | Locked in place, vibrating | Close but sliding past each other |
| Flows? | No | Yes |
| Compressible? | Almost not at all | Almost not at all |
Which should you use?
Solid
It's a solid when it holds its own shape without a container — like ice, wood, or metal.
Liquid
It's a liquid when it flows and takes the shape of whatever holds it, while keeping the same volume — like water or oil.
Frequently asked questions
- What's the main difference between a solid and a liquid?
- Shape. A solid keeps a fixed shape because its particles are locked in place; a liquid flows and takes its container's shape because its particles can slide past each other. Both keep a fixed volume.
- How does a solid become a liquid?
- By melting. Adding heat makes the solid's particles vibrate more until they break free of their fixed positions and can flow — turning it into a liquid.
- Do both have a fixed volume?
- Yes. Both solids and liquids keep the same volume and are very hard to compress. The difference is that only the liquid changes shape to fit its container.