Everything is made of atoms - the air we breathe, the water we drink, the food we eat, the things we use.
Atoms cannot be seen even with the most powerful microscope. Atoms are so small - it has taken scientists many, many years to find out what they are like, and how they are made.
There are over a hundred kinds of atoms. An atom of hydrogen is one of the simplest kinds. Hydrogen is a gas we cannot see, but it is part of the air we breathe.
The atom is made of two parts. the centre part is called the nucleus. The tiny part moving round it is called an electron.
The electron is always moving round the nucleus, rather like the way the planet Earth moves around the Sun. The whole atom is held together by electricity.
Other atoms have different number of electrons moving around their centre parts. The atom of iron has 26 tiny electrons moving around it at a very high speed. The nucleus of this atom is much more complicated than the nucleus of the hydrogen atom.
Everything is made of atoms, or group of atoms. A group of atoms joined together is called a molecule.
The Molecule of water is made up of two atoms of hydrogen and one atom of oxygen. The atom of oxygen has eight tiny electrons moving round the nucleus.
Oxygen and hydrogen are gases and, when right amounts are mixed, they produce water.
All the water you drink is made of molecules like this. There are millions in every drop of water.
Just as a torch sends out a ray of light, so some atoms send out rays of tiny particles. These atoms are called radio-active atoms. The rays are used a lot in hospitals and often help to cure people who are ill. Atoms can also be made to send out rays called X-Rays. These Rays can go right through the soft parts of our bodies and cast shadows of our bones.
In this way, doctors can get X-Rays pictures of our ones to see if they are broken. The person being X-rayed feels nothing. He is simply photographed by a special camera.
There is tremendous power locked in the nucleus of an atom. This is released when the atom is broken up, just like a ballon when popped.
Scientists know how to split the atom. This means that they know how to break up the nucleus. This is called nuclear fission.
We know how to use this power to make electrcity, which we then use for heating and lighting in our homes.
Electricity can be produced in a big nuclear power station.
Most nuclear power stations make power from the atoms of Uranium. Uranium, like coal, is mined out of the ground. It is interesting to note that 1 ton of Uranium gives about as much power as 10000 tons of coal.
Some submarines are driven by atomic power, and it can go all the way around the world without re-fuelling.
Power can be created also by "splitting" the atom. This is called nuclear fusion because the centre parts of the atoms fuse together. The reason why the sun shines is because it is very hot and it is a huge ball of hot flames which gets it heat by fusing atoms of hydrogen together. It is this nuclear power which makes the stars shine.