• Joseph Proust (France)

    Joseph Proust (France)
    law of definite proportions
  • John Dalton (England)

    John Dalton (England)
    discovers atoms
  • Amadeo Avagadro (Italy)

    Amadeo Avagadro (Italy)
    gases are made up of atoms and can be accounted for
  • Henri Becquerel (France)

    Henri Becquerel (France)
    discovered radioactivity
  • JJ Thompson (England)

    JJ Thompson (England)
    electron discovery
    plumb pudding model
    isotopes- chemically similar, but different in mass
    2 kinds of neon
  • Max Planck (Germany)

    Max Planck (Germany)
    introduced hypothesis that oscellating atoms absorb and emit energy
  • Robert Millikan (US)

    Robert Millikan (US)
    measured charge on single atom
    oil-drop experiment
  • Lord Rutherford (England)

    Lord Rutherford (England)
    charge of electron is negative

    photoelectric effect
  • Max Born (Germany)

    Max Born (Germany)
    definition of quantity of heat
  • Louis de Broglie (France)

    Louis de Broglie (France)
    electron waves theory
  • Erwin Schrodinger (Austria)

    Erwin Schrodinger (Austria)
    atoms organized through electric clouds instead of power level
  • Werner Heisenberg (Austria)

    Werner Heisenberg (Austria)
    uncertainty principle
  • Walter Bothe (Germany)

    Walter Bothe (Germany)
    momentum and energy are conserved at atomic level
    cosmic rays consist of massive particles
  • Wolfgang Pauli (US)

    Wolfgang Pauli (US)
    energy and momentum lost when electron is expelled from the nucleus
  • James Chadwick (England)

    James Chadwick (England)
    discovered neutron