Question

Describe the major contribution of Dalton's atomic theory to the understanding of atomic structure.

A) Electrons can only be located in circular, concentric shells.
B) Chemical elements are made up of identical units called atoms.
C) Discovery of the existence, location, and charge of the nucleus.
D) The determination of the identity of the three subatomic particles.

Answer 1

B) Chemical elements are made up of identical units called atoms.

John Dalton was the one who discovered "all matter is made of atoms". Democritus was the one who suggested that atoms were there but it was not scientifically proven until 2 centuries later when John Dalton proved it.