Democritus' Greek model of the atom was the first model of the atom.
Democritus claimed that if objects were broken down smaller and smaller, they would eventually reach a size where they could no longer be broken.
He was one of the Atomic Theory's two original founders. His reasoning for the hypothesis was that matter was made up of small building blocks called atoms.
At the time, this theory was extensively questioned. Because people were not used to accepting new ideas and/or philosophical and scientific conceptions.
This theory was only partially right, and as modern scientists delved deeper into Democritus' work, they began to formulate other theories and hypotheses regarding the atom.