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Year 7 KS3

Melting and Freezing

Hold an ice cube in your hand. What happens?

The ice cube changes states. From a solid to a liquid, but why? What’s making the particles in the ice move and turn into water?

You are constantly producing heat, your cells are constantly working, growing and dividing. As a by product of that, they produce heat. When you’re cold, your body produces more heat.

Particles in the ice cube take the energy from their surroundings.

They being to vibrate faster and move out of place and get further away. Turning from a solid to a liquid.

On the other hand, if we remove the energy from something, then we can slow the particles down. This makes essentially makes them organised and form a solid.

When blacksmiths shape metal, you notice they heat it up to very high temperatures. Once the metal is shaped, they put it in water to cool it. Making it particles solid again.

The point where a solid becomes a liquid is called it melting point.

Melting point is the amount of heat required to turn a substance from a solid to a liquid.

Click here to learn about graph analysis for melting and freezing points.

If we go one step further, and continue to ad energy into

the substance, it will eventually turn from a liquid to a gas.

This is called boiling.

Boiling happens if enough energy is transfer to the particles. Different substances have different boiling points.

Click here to learn more about graph analysis for boiling points.

As you can see in the animation, the more heat (energy) we put in, the more the water molecules absorb, and the more the move.

Click here to learn how to interpret graphs on melting point, freezing point and boiling point.


Click here for a worksheet on particle theory

Moving through the states

Evaporation

(Liquid to a gas)

Condensation

(Gas to a liquid)

Melting

(Solid to a Liquid)


Freezing

(Liquid to a Solid)


Sublimation

(Solid to a gas)

Desublimation

(Gas to a Solid)