Introducing the atom

Stella is on a beach, building a sandcastle. Grains of sand make up the beach where Stella is, and they are like building blocks that Stella can use to build sandcastles. Are the grains of sand themselves made of something, too? Yes! Sand is made of very tiny particles — so tiny you can't even see them!

These particles are atoms. Atoms are the building blocks that make up the world. They make up the sand, as well as the air, the ocean, the seaweed… even the smell of the seaweed! Atoms make up everything you can see, touch, smell, and more! Oh, wow.

There must be a lot of atoms in the world! So many, it’s hard to imagine! One single grain of sand is made up of more atoms than the total number of grains of sand on Earth! Wow. Are all these atoms the same?

Well, yes and no. All atoms have the same parts. You can think of a single atom as a tiny solar system, with the Sun in the middle and planets going around it. Instead of the Sun, an atom has a nucleus at the centre. And instead of the planets, there are extremely small particles that rotate and spin around the nucleus.

These are the electrons. Every atom has both a nucleus and electrons. But the size of the nucleus, and the number of electrons can differ, so there are different types of atom. There are about 100 different types, all with their own unique properties. - But... if there are only one hundred different atoms, how can there be millions and millions of different things in the world?!

Well, let’s think back to that sand castle. You can use the same sand, from the same beach, to build all kinds of different sandcastles. You can even mix different building blocks - add water, rocks, sticks or shells, and create countless variations. It is the same with atoms. Because atoms are like building blocks, they can be combined in different ways, to make new things.

If these two atoms combine with this one they make up a new particle — a molecule. This one here is a water molecule. And molecules can come together to build even bigger things, like the ocean, the beach, or you! Oh no, a beach ball ruined my castle! Now it’s just a pile of sand!

But what happened to the atoms in the sandcastle?! The beach ball ruined the castle, but it didn’t destroy the individual grains of sand, nor the atoms they are made of. Changing or destroying an object does not change the individual atoms that make it up. Instead, the atoms are simply rearranged again, to form something different!