What about the substances? Which substances do we know?
That is really easy to understand:

• Imagine you have a bunch of beautiful balloons.
• You set them free in an empty room.
• The balloons spread regularly in the room, keeping the same distance to each other.
• You can move them by hand, but they will go back to their original position.

• The temperature in the room becomes colder. Much colder than before.
• The balloons react by falling to the floor.
• They cover the whole floor, some are even lying on top the others.
• If you jump in between the balloons they easily move away.

This happens if the substances are liquid ones. You can compare that with what happens, when you are swimming!

• Now the temperature falls once more. It’s really icy in the room.

• The balloons narrow the distance between them, they fill every empty space. Smaller atoms fit easily in between the bigger ones.

• Now it is impossible to move them or separate them from each other. A solid mass builds itself up.

Imagine – this is the way atoms build up solid substances. What did you recognize?

Temperature changes the states of substances on the whole. The best examples for that are first of all steam – which comes out of your teapot, when the water boils! Second you know example of water and swimming. Third you can think of a lake covered with ice. Steam, water and ice are the same substance, only temperature differs.
That is very important for the next station of our journey.

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