Atomic Theory Time Line

James Chadwick - proved the existence of neutrons.

Gold Foil Experiment - Ernest Rutherford shot a beam of alpha particles at a sheet of gold foil, a few of the particles were deflected.

Cathode Ray Tube Experiment - J.J Thomson, showed that all atoms contain tiny negatively charged subatomic particles or electrons.

Antoine Lavoisier - created the Law of Conservation of Mass

Niel Bohr - electrons could only occupy particular orbits determined by the quantum of action

Ernest Rutherford - established the nuclear theory of the atom with his gold-foil experiment. He concluded that a tiny, dense nucleus was causing the deflections.

Rutherford Model - the electrons orbit the nucleus similar to the orbit of planets about the sun

Erwin Schrodinger - created The Schrodinger Equation and the Electron Cloud Model

Electron Cloud Model - electrons were no longer depicted as particles moving around a central nucleus in a fixed orbit.

Democritus; Created the formulation of an atomic theory of the universe

J.J. Thomson; created the plum pudding model, showing that electrons have a negative electic charge

Ernest Rutherford; Created the gold foil experiment which led him to find a nucleus in the atom

Neils Bohr; Created the Bohr Planetary Model, depicts the atom as a small positive atom, with electrons orbiting around the nucleus

John Dalton; Created a theory that proposed all matter was composed of atoms

Robert Millikan; Created the oil drop experiment to help quantify the charge of an electron