A few weeks ago I wrote to you about how everything was made of tiny little lego-brick-like atoms. Later, I wrote about how some things, like gold and diamonds, are made up of the same type of atom-brick. But like most toys made from of lego bricks, most things in reality are made up of many different types of atom joined together not just one type.
Like lego, atoms can be made to join with other atoms to make bigger and more complicated shaped bricks. These bigger bricks are known as molecules. It is this fact that makes the world around us full of very different types of stuff. Although the whole universe, that we know of so far, is made up of just 98 types of atom you can build very different types of things by joining them together in different ways and different arrangements. It is worth saying that although they are bigger than atoms, molecules are still very very small things indeed. Even the big complicated ones.
The above picture shows six lego brick molecules that I made up in my head using just four types of lego brick. It didn’t take me very long to do. Have a go yourself if you have some lego or other building blocks at home. Make some models of molecules and see how easy it is to come up with new shapes using only a few types of brick.
A good example of a very simple and small molecule is water. It is made of one type of atom brick joined up with two types of another. One drop of water contains huge numbers of these molecules rubbing against and sliding around each other. It just so happens that this combination and arrangement of atom bricks makes stuff that is wet in warm weather but frozen solid when it’s cold and that can turn into vapour when it gets very hot, such as in a kettle.
For an example of a much more complicated molecule that contains lots of different types of atom bricks you need look no further than your own hair and finger nails. Much of these parts of you is built from molecules of something called keratin. One molecule of keratin is made of more than 4000 atoms stuck together in a long spiral shape. These molecules stick to each other to make very long, strong chains. If water is just like three Lego bricks of two different types joined together then this molecule is like the Lego Star Wars Death Star - made of lots of bricks of lots of different types. The Death Star model has 3803 bricks to be exact so a keratin molecule has even more parts than that. Even so, it is still very small because atoms are incredibly tiny things indeed.
Because they are all sorts of shapes and sizes each type of molecule acts differently to others. This is why millions of water molecules together in a glass of water are see-through and liquid but lots of keratin molecules create tough bendy stuff like your nails.
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