Atomic Theory

Democritus

370

Greek philosopher

John Dalton

Mar 16, 1803

Hypothesized that the atom was a tiny
hard sphere, Believed that atoms of a given element
are identical, Created the atomic theory

JJ Thompson

Mar 16, 1897

Discovered the electron, Used the cathode ray tube in his
discovery, Created the “plum pudding” model of
the atom.

Ernest Rutherford

Mar 16, 1911

Did the gold foil experiment, Discovered that the proton had a
positive charge, Discovered that the atom is mostly
empty space,

Niels Bohr

Mar 16, 1915

Created a model of the atom with
electrons moving around the nucleus in
fixed orbits ,

Werner Heisenburg

Mar 16, 1925

Uncertainty principle
A particle’s position, energy, and time
can never be precisely known, Worked with the Quantum Theory

James Chadwick

May 21, 1932

Deiscovered the neutron and founde the missing mass of the atom's nucleus.