Who is the scientist who developed a model called the atomic theory of matter?

John Dalton (1766-1844), an English chemist, developed the model called the atomic theory of matter. Although Democritus had earlier suggested the existence of the atom, it was about two millennia later that John Dalton developed the atomic theory of matter.

Dalton's theory of matter still remains essentially relevant today even though the present concept of atomic theory is a little more involved than Dalton's model. For example, we now know that nuclear reactions can destroy atoms as opposed to Dalton's theory which posits that atoms are indivisible and indestructible, even though we still acknowledge that ordinary chemical reactions cannot destroy atoms.

Similarly, atoms of different masses exist within an element as isotopes although isotopes within a given element have the same chemical properties. Dalton's theory had posited that atoms in a given element are all identical in mass and properties.

Not withstanding these later findings, Dalton's theory quickly explained several chemical phenomena that were hitherto unexplained.