History of the Atomic Model

By Schwifty_231
  • 500 BCE

    Democritus proposed the existence of atoms.

    Limited technology at the time meant this was just an idea and could not be tested

  • John Dalton developed his theory of atoms and matter.

    John Dalton developed his theory of atoms and matter.
    Experiments in chemistry and careful measurement of results allowed Dalton to support his hypotheses with evidence.

  • JJ Thomson discovered the electron.

    JJ Thomson discovered the electron.
    Experiment using electric charges in cathode ray tubes

  • Ernest Rutherford developed the planetary model of the atom.

    Experiment using alpha particles fired at thin gold foil and an early prototype Geiger counter to measure results.

  • Niels Bohr developed a model of the atom.

    Niels Bohr used mathematical models and laws of quantum physics to propose his updated model.

  • The neutron was discovered by James Chadwick.

    The neutron was discovered by James Chadwick.
    Experiments using kinematics and accurate measurements lead to proving the existence of a previously undetected subatomic particle, the neutron.