Chemistry - Atoms

Atoms are one of the fundamental ides in Chemistry, but how were they discovered? Greek philosophers were very good at carrying out 'thought experiments'. One of these was done by Democrites who considered what might happen if you took a piece of rock and hit it with a hammer. It's not too difficult to work out that it would shatter. But then he wondered about what would happen if you then took one of the smaller pieces and hit that with a hammer and so on. He decided that you would probably end up with a piece so small that it could not be broken any smaller. The Greek word for 'indivisible' was 'atomos' and that is the origin of the word 'atom'.

Almost 2000 years later, the idea of atoms re-surfaced. They were seen in the same way as Democritus saw them - small, solid spheres. That seemed very logical but gradually, scientists began to discover that the 'indivisible' atoms were in fact divisible which lead to the idea that atoms were more like a current bun - a lump of matter with the particles spread through it. Later, it was found that atoms were mainly open space with a tiny nucleus and the electrons were regarded as orbiting like planets. Then in the 20th century it was realized that electrons orbit the nucleus in 'shells' and the discovery of neutrons completed the picture.

It was realized also that the number of electrons in the outer shell determined the chemical properties of a particular atom. In fact, the arrangement of electrons is the basis for another fundamental part of Chemistry - the periodic table... but that's a whole different story for another quiz!