Democritus ⑴ E. described materials as being made of small particles. He called the particles atoms.

John Dalton ⑵ C. atoms are small, indivisible; solidsphere model

J.J. Thomson ⑶ D. discovers the electron and proposes the Plum Pudding Model

Ernest Rutherford ⑷ F. discovered that an atom is mostlyempty space.

Niels Bohr ⑸ A. discovered the electrons travel in energy level (orbitals)

Erwin Schrodinger ⑹ B. came up the idea of electron cloud Instead of orbitals