THE MADE OF THE WORLD

Everything around us, including our own bodies, is made of specks of matter called atoms. There are many different kinds of atoms, but all of them are extremely small. They are so tiny that even something as small as a sugar cube contains about half a billion of them, packed closely together. If the atom in just one sugar cube were shared out among the entire human population of the world, we would each have about 100 million of them.

What happens when something melts?
In solid substances, such as ice, molecules are packed closely together. Forced hold neighbouring molecules together, which makes the material hard. But if you warm a piece of ice, the forces start to weaken, the molecules drift apart, and the ice starts to melt. If the heat is maintained, the molecules move faster and faster, until they are moving so quickly that they escape into the air. The water turns into steam, and eventually all of it disappears. If the steam is cooled, the molecules slow down. It turn back into water, then if it gets cold enough, back into ice.

In steam, molecules move about quickly. In liquid water, they move more slowly and are closer together. In ice, they are packed together to make crystals