Atom Timeline

By tonyh
  • 400


    Everything is composed of atoms, which are physically, but not geometrically; indivisible. Atoms are instructable, in motion, and infinite number of atoms
  • Period: 400 to

    Atom TImeline

  • John Dalton

    Atomic Theory: matter is made up of atoms that are indivisible and indestructible.
  • James Chadwick

    Used a method for tracking particle radiation and knocked the protons out of the nucleus. The nucleus still had mass, finding that neutrons exists.
  • J.J. Thomson

    discovered electrons by experimenting with cathode ray. cathode rays were negatively charged. studied positively charged particles in neon gas.
    proposed plum pudding model
  • Robert Milliken

    Oil Drop Experiment: determined size of the charge on an electron. Determined there was a smallest unit charge or a charge that is quantized.
  • Ernest Rutherford

    overturned Thomson's model. Gold foil experiment: demonstrated that the atom has a tiny, heavy nucleus.
  • Neils Bohr

    Quantum Theory: energy is transferred only in certain well defined quantum. Electrons should only move around the nucleus in a prescribed orbit.