Substances are made up of particles.

Particles in a solid are constantly moving.

The particle model helps us explain why solids and liquids have different properties.

Flour can be poured like a liquid because its particles are not closely packed together.

New substances are formed during melting and freezing.

A chemical reaction take place when substances react to form one or more new substances.

Look at the diagram of the particle model below! This the particle model of a ....

Look at the diagram of the particle model below! This the particle model of a ....

Which of these explains why liquids can change in shape?

Emma leaves a piece of chocolate under the hot Sun. The chocolate is ....

Emma leaves a piece of chocolate under the hot Sun. The result is shown by the picture below. The chocolate changes from a solid into a ....

Look at the picture! The change of the chocolate is called a .... reaction.

Burning a matchstick is a physical reaction.

Melting butter is a physical reaction.

Baking bread is a chemical reaction.

Mixing salt and water is a physical reaction.