Democritus (460—370 B.C.E.) Democritus was born at Abdera, about 460 BCE, although according to some 490. Democritus expanded the atomic theory of Leucippus. Democritus, known in antiquity as the ‘laughing philosopher’ because of his emphasis on the value of ‘cheerfulness,’ was one of the two founders of ancient. Democritus ( chosen of the people ) was an Ancient Greek philosopher born in Abdera, Thrace, Greece. He was an influential pre-Socratic philosopher who formulated an. Democritus (/ d ɪ ˈ m ɒ k r ɪ t ə s /;. The Democritean atom is an inert solid (merely excluding other bodies from its volume) that interacts with other atoms. In chemistry and physics, the atomic theory explains how our understanding of the atom has changed over time. Atoms were once thought to be the smallest pieces of matter. Much of the best evidence of Democritus' theory of atomism is reported by Aristotle in his. but in ancient Greece the atomic theories of Democritus remained. atomic theory = explaining macroscopic phenomenon through the behavior of microscopic atoms, in this case, kinetic behavior temperature = velocity of atoms Democritus, ancient Greek philosopher who is credited with the birth of atomic theory. Credit: phil-fak.uni-duesseldorf.de This was Democritus’ atomic model. It was simply a round sphere with no electrons, protons, or neutrons. Democritus created the first atomic model. Democritus, (born c. 460 bce —died c. 370), ancient Greek philosopher, a central figure in the development of philosophical atomism and of the atomic theory of the.