Atomic Theory Timeline

By meghanbraas
  • Democritus
    440 BCE

    Democritus

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

    Atomic Theory Timeline

  • Atomic Model
    440

    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