Complicated and sensitive instruments enabled modern scientists to approach the problem which had for long absorbed the alchemists of olden days: what constitutes matter. In the past, scientists believed all matter was made up of tiny particles, each of which was given the name of ‘atom’ from the Greek meaning ‘indivisible’.

Modern scientists have managed to weigh the atom and have also succeeded in examining its structure. They have discovered that the incredibly small world of the atom is like an infinitely small solar system with a sun at the center and planets revolving round it in different orbits. The sun in this system is called the nucleus and the planets are the electrons.

Today scientists can alter matter by acting on the atomic nucleus: this is what nuclear physics is about. But what exactly is an atom? To understand, we must take any piece of matter: for example, a lump of sugar. We then break up the lump into smaller pieces and those pieces into even smaller pieces. We do this hundreds of thousands of times until we reach particles that are so small that they no longer by broken down. This basic particle of sugar that we have obtained is called a sugar molecule. Let us imagine that we could grasp one of these molecules and break it up. The molecule would then break up into forty-five pieces consisting of twelve atoms of carbon, twenty-two of hydrogen and eleven of oxygen. The sugar no longer exists: all we have are atoms of carbon, hydrogen and oxygen, the materials of which sugar is made.

If we could bread down a molecule of water we would obtain three atoms: two of hydrogen and one of oxygen.

Sugar, water, rocks, metals, wood, food, our bodies and everything in nature, consists of atoms. These atoms are arranged in various groupings to produce different materials and substances.