Atomic Theory Timeline

By meghanbraas
  • 440 BCE

    Democritus

    Democritus
    Atoms are "uncuttable."
    Atoms are small, hard particles.
    Atoms constantly move.
  • Period: 440 BCE to

    Atomic Theory Timeline

  • 440

    Atomic Model

    Atomic Model

  • John Dalton

    John Dalton
    All substances are made of atoms.
    Atoms of different elements are different.
    Atoms of the same element are exactly alike.

  • Atomic Model

    Atomic Model

  • 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.

  • Atomic Model

    Atomic Model

  • Ernest Rutherford

    Ernest Rutherford
    Atoms contain mostly empty space. Electrons move in empty space in the atom. He conducted the gold foil experiment. Most of an atom's mass is in the nucleus. There is a small, dense, positively charged nucleus.

  • Atomic Model

    Atomic Model

  • Niels Bohr

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

  • Atomic Model

    Atomic Model

  • Erwin Schrodinger and Werner Heisenberg

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

  • Atomic Model

    Atomic Model