Particles gain or lose energy when a substance changes state.

When a particle of a substance in the liquid state at the surface, has enough energy to change to the gas state and mix with air.

The evaporation rate is a measure of how quickly a substance evaporates.

Ethanol is a type of alcohol that has a higher evaporation rate than water.

Changes of state: energy and evaporation

Science

Solid and liquid states

Melting: particle model

Bunsen burners

Melting: melting points and freezing points

Particle model of substances in the gas state

Boiling and condensing

In the Solutions unit, pupils will build on their understanding of the states of matter to learn about mixtures, solutions, and dissolving in terms of the particle model.

In Y4 of primary science, pupils learnt about ‘solids, liquids and gases’ and changes of state.

This unit covers the properties of solids, liquids, and gases using the particle model, including gas pressure. It explains changes of state in terms of the particle model while developing skills in using appropriate techniques, apparatus, and materials in lab work.

Solid, liquid, gas states and changes of state

Order the states of matter from lowest to highest energy.

Water can evaporate at temperatures lower than 100℃.

What happens to the energy of a substance when it changes from a gas to a liquid?

When changing from the solid to liquid to gas state, {{}} is required to overcome forces of attraction between particles.

Which two substances are commonly used in thermometers and can change state at fairly low temperatures?

A liquid is heated and the volume reduces, but no bubbles of gas form.

A process that can take place at any temperature above melting point.

Cooking pasta in a pot of water that is producing a lot of bubbles of gas.

Forming a gas from a liquid, but a specific temperature needs to be reached.

Some students are revising the differences between boiling and evaporating, and they mix up their revision cards. Select **all** the statements below that are about evaporation.

Which state of matter has no fixed shape, but a definite volume and can flow?

The {{}} point is the temperature at which a liquid turns into a gas.

Which state has the weakest forces of attraction between the particles?

Which state of matter undergoes a change in volume when compressed?

Less particles at the surface in touch with the air.

The water is spread out over a greater area.

The two beakers below, with the same volume of water in each, were left in a room. Select **all** the true statements about **Beaker A**.

The sun is not powerful enough to dry up the the bird bath in the winter.

The sun evaporates the water in the summer but cannot in winter.

There are still sunny days in the winter which can dry up the bird bath.

Water can still evaporate even if the weather is not sunny.

It is winter. The bird bath in the school garden needs refilling. Some primary children discuss whether evaporation could be the reason that the bird bath is empty. Which reason is correct?

Changes of state: energy and evaporation

Lesson outcome