Added:
Democritus (Greek: ΔημόκÏιτος, DÄ“mokritos, "chosen of the people") lived approximately between 460 BCand 370 BC, so roughly it must have been about 420 BC, certainly not 250 BC as stated in this answers up till now.
i think about 404 BC because that what a bunch of other sites told me but I'm not positive...
Democritus developed his atomic theory of the universe in the 5th Century B.C. He was aided by Leucippus in establishing this theory.
400 B.C.
he did not develop anything regarding the 'atomic theory' for he was against that theory.
He pubish is own atomic theory in 1803 developed his atomic theory by observations gathered from many experiments .
john Dalton
460 B.C. or for atheists BCE
Democritus formulated the first atomic theory. He said that atoms were tiny and constantly moving. Democritus was a Greek philosopher.
he did not develop anything regarding the 'atomic theory' for he was against that theory.
Democritus achievements are his atomic theory and his book -on the little order of the world- which describes his atomic theory.
They both thought the same theory but Dalton had evidence to prove it, unlike Democritus.
democritus was greek philosophers.
the atomic theory of the universe
Democritus created the "Atomic Theory" and he was also a teacher.
The ancient Greeks did not perform any experiments to test the atomic theory proposed by Democritus. To the ancient Greeks the atomic theory was a part of philosophy, not science.
460 b.C
400b.C.
2012
He pubish is own atomic theory in 1803 developed his atomic theory by observations gathered from many experiments .
460 b.C.