Democritus from Abdera
democritus
Democritus (460BC - 370BC)
Its RADIOACTIVITY!! That was the first discovery that rejects the idea that the atom is indestructible
Robert Boyle
Democritus did not have experimental evidence to support his idea of the atom. Instead, his idea was based on philosophical reasoning and speculation.
No device can give the complete structure of an atom but you can get a minute idea about the look of an atom using an Electron Microscope!
He discovered the atom
450 b.c
The idea of the atom was first developed by Greek philosophers Leucippus and Democritus in 5th century BC. Their idea was overlooked until Antoine Lavoisier's experiments were done in the 18th century.
John Dalton put forward the idea that each element is made of a different sort of atom. Each kind of atom had its own properties such as an individual mass.
manu
450 BC. Hope it answers your question =)