The beginnings of atomic research

The word ‘atom’ is derived from the Greek ‘atomos’, meaning indivisible. In about the year 400 BC the Greek philosopher Democritus postulated that all matter was made up of minute particles which could not be destroyed or broken up. He was unable to perform any experiment to support his hypothesis, but this concept could account for the fact that different substances had different densities: the more the atoms were compressed the denser and heavier the substance became. A few Greek sages accepted the atomic theory of Democritus, but the great majority adopted the view of Aristotle, who believed that matter was continuous in structure, and this was also the opinion held by the alchemists in the Middle Ages. When modern scientific research began in the seventeenth and eighteenth centuries, the concept of atoms was revived and appeared in the writings of scientists, but it was generally mentioned incidentally and no attempt was made to use it to explain natural phenomena or to verify it experimentally.

John Dalton is regarded as the father of modern atomic theory. He was an English teacher who dabbled in chemistry as a hobby and became one of the founders of modern chemistry.