How were atoms discovered

The invention of the atom

Water, fire, air and earth - for the early Greeks the basic building blocks of matter © MMCD

Even in ancient times, our ancestors thought about what our world is made of - what forms and holds together matter. The fact that they hardly had any opportunity to look into the microcosm or to carry out complicated experiments was not an obstacle. Because some characteristics and behaviors of substances and materials could be observed even then. For example, liquids disappeared at higher temperatures and a gas took their place. Or that the properties of some substances changed when they reacted with others.

For the Greeks, the conclusion from all these observations was clear for a long time: All matter consists of only four basic elements: fire, water, air and earth. In her opinion, every substance, regardless of whether it was the wood of a tree or the wine in a drinking cup, consisted of a mixture of these four basic qualities. They also explained the states of aggregation with this model: Gaseous substances should therefore primarily contain air, solid materials, on the other hand, mainly earth, while liquids, in turn, predominantly contain water.

Democritus postulated the idea of ​​the indivisible atoms © historically

"Only atoms in empty space"

But in the fourth century BC, the natural philosopher Democritus developed a new, absolutely revolutionary idea: It is not the four elements that are the basis of all matter, he postulated, but tiny, solid and indivisible particles: “A thing only appears to have a color, only it appears to have a color is it sweet or bitter; in reality there are only atoms in empty space, ”the natural scientist Galen later quotes Demokrit's statements. According to his idea, the atoms should all be the same in their properties, but differ in their shape - round, cube-shaped, cylindrical or pyramidal. And only the combination and number of these atomic shapes creates the different materials and their typical characteristics.

Even if Democritus neither correctly recognized the nature of atoms nor the way in which different materials are created from them: With his model, the idea of ​​the atom as the basic building block of matter was born. However, it would be well over 2,000 years before researchers began to study the properties of atoms in more detail.

Nadja Podbregar
Status: June 21, 2013

June 21th 2013