How did scientists come up with the theory of atoms?

There were two theories. One said, that matter is created by the four elements Water, Fire, Wind and Earth. A second theory postulated, that everything is made up from small building blocks (they didn't define a specific shape) which are indestructible, called atom. Atom comes from átomos, which means impartible. read more

In short, this was a reasonably accurate (for the time) theory of genetics. The next real advance hovered around phlogiston. To make the phlogiston theory work, there had to be elements that gave up phlogiston to dephlogisticated air (oxygen) and formed calces. read more

formulated an atomic theory of matter with 4 postulates: 1. Elements are composted of small particles called atoms. 2. All atoms of a given element are identical. * 3. Atoms are neither created nor destroyed in chemical reactions. 4. Compounds always contain the same proportion of elements. read more

Democritus was never married. His mentor, Leucippus, originally came up with the atomic theory, but it was then adopted by Democritus. The atomic theory stated that “The universe is composed of two elements: the atoms and the void in which they exist and move.” According to Democritus atoms were miniscule quantities of matter. read more