Atomic Theory Timeline

  • Democritus
    440 BCE

    Democritus

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

    Atomic Theory

  • Democritus
    440

    Democritus

    Atomic Model
  • John Dalton

    John Dalton

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

    John Dalton

    Atomic model
  • J.J Thomson

    J.J Thomson

    He conducted the cathode-ray tube experiment
    His theory of the atomic structured lead to the "pluming-pudding" model
    There are small negatively charged particles inside an atom
  • J.J Thomson

    J.J Thomson

    Atomic Model
  • Ernest Rutherford

    Ernest Rutherford

    Atoms mostly contain empty space
    Electrons move in empty space in the atom
    He conducted the gold foil experiment
    There is a small dense positively charged nucleus
  • Ernest Rutherford

    Ernest Rutherford

    Atomic Model
  • Niels Bohr

    Niels Bohr

    Electrons jump between levels from path to path
    Electrons travel in definte paths
  • Niels Bohr

    Niels Bohr

    Atomic model
  • Schrodinger and Heisenberg

    Schrodinger and Heisenberg

    Electron paths cannot be predicted
    Electrons are found in electron clouds not paths
  • Schrodinger and Heisenberg

    Schrodinger and Heisenberg

    Atomic model