Atomic Theory Timeline

By desilvaan
  • 400 BCE

    Democritus

    Democritus
    Atoms are “uncuttable.”, Atoms are small, hard particles.Atoms constantly move.

  • John Dalton

    John Dalton
    All substances are made of atoms.Atoms of different elements are different.Atoms of the same element are exactly alike.Elements combine in specific proportions.He conducted experiments in combining elements.

  • J.J. Thomson

    J.J. Thomson
    He conducted the cathode-ray tube experiment. His theory of the atomic structure lead to the “plum-pudding” model. There are small, negatively charged particles inside an atom.

  • Ernest Rutherford

    Ernest Rutherford
    Atoms contain mostly empty space.Electrons move in empty space in the atom. There is a small, dense, positively charged nucleus

  • Niels Bohr

    Niels Bohr
    Electrons jump between levels from path to path. Electrons travel in definite paths.

  • Erwin Schrӧdinger and Werner Heisenberg

    Erwin Schrӧdinger and Werner Heisenberg
    Electron paths cannot be predicted. Electrons are found in electron clouds, not paths.