Legend 'Hellenic Republic' in Greek, symbol of atom, denomination (drachmes), the year of minting.

Legend 'Democritus' in Greek, bust of Democritus left. Democritus was a pre-Socratic Greek philosopher ( 460 - 370BC), who developed the atomic theory of the universe.

 ...all matter is made up of indivisible elements which he called 'atomos'.