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Solid vs. Liquid: What's the Difference?

ScienceSide-by-sideWritten comparisonAll comparisons

Read the comparison below, or explore it visually. Create a visual lesson comparing solid and liquid using available credits or plan allowance.

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.

At a glance

SolidLiquid
ShapeFixedTakes its container's shape
VolumeFixedFixed
ParticlesLocked in place, vibratingClose but sliding past each other
Flows?NoYes
Compressible?Almost not at allAlmost 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.