History of modern Atomic theory

THE HISTORY OF THE MODERN ATOMIC THEORY

 

400 BC           Democritus                Proposes the idea of the atom

 

1807               John Dalton                Founder of modern atomic theory

                                                            His model survived for almost 100 years

 

1885               J.J. Thomson Discovery of the “proton”

 

1896               Henri Becquerel        Discovery of Radioactivity

 

1897               J.J. Thomson Discovery of the “electron”

 

1903               J.J. Thomson “Plum-pudding” model

 

1909               Ernest Rutherford      The Gold Foil Experiment

 

1911               Ernest Rutherford      Rutherford’s model of the atom

 

1913               Niels Bohr                  Electrons exist in discrete energy levels

 

1923               Robert Millikan          The Oil Drop Experiment

                                                            Discovered the charge of an electron

                                                            Discovered the mass p+ = 1836 the mass of e-

 

1923               Erwin Schrodinger    Wave Particle duality

 

1925               Erwin Schrodigner    Quantum Mechanical Model of the Atom

 

1932               James Chadwick      Discovery of the “neutron”

 

1945               Wolfgang Pauli          Pauli Exclusion Principle