Progression of the Atomic Theory

  • Law of Definite Proportions

    Law of Definite Proportions
    Joseph-Louis Proust conclude that every chemical compound contains fixed and constant proportions of its constituent elements.
  • Cathode Ray Tube

    Cathode Ray Tube
    Fires electrons at a screen of phosphors (not phosphorous) to produce an image.
  • J.J. Thomson

    J.J. Thomson
    Discovered the electron. Proposed the plum pudding model of the atom, as a positively charged body scattered with the negatively charged electrons.
  • Plum-Pudding Model

    Plum-Pudding Model
    J.J. Thomson proposed his atomic theory that atoms were a positively charged fluid scattered with negatively charged electrons.
  • Robert Millikan

    Robert Millikan
    Experimented with droplets of oil to discover the exact charge of an electron.
  • Gold Foil Experiment

    Gold Foil Experiment
    Fired alpha particles at a piece of gold foil, some of which bounced back, disproving Thomson's idea of the plum pudding model.
  • Bohr Planetary Model

    Bohr Planetary Model
    Proposed by Niels Bohr, this model suggests that the atom has a superdense nucleus of protons and neutrons, orbited by electrons in a regular motion.
  • Erwin Schrodinger

    Erwin Schrodinger
    Won a Nobel Prize for making many important contributions to the field of Quantum Mechanics.
  • Lise Meitner

    Lise Meitner
    Publishes the results of her experiments on radioactive substances, discovering nuclear fission and proving that nuclei aren't static.