Atomic Theory Timeline

By santosjd
  • 440 BCE

    Democritus

    Democritus
    Atoms are: uncuttable, small but hard particles and constantly moving

  • John Dalton

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

  • J.J. Thomas

    J.J. Thomas
    He conducted the catheode-ray tube experiemnt
    His theory of the atomic structure lead to the "plum-pudding" model

  • Ernest Rutherford

    Ernest Rutherford
    -Conducted the gold foil experiment
    -Found that most of the atom's mass is in the nucleus
    -Said atoms contain mostly empty space
    -Found that there is a small, dense, positively charged nucleus

  • Niels Bohr

    Niels Bohr
    -Said that electrons jump between levels from path to path -Electrons travel in definite paths

  • Schrodinger

    Schrodinger
    -Electron paths can't be predicted
    -Electrons are found in electron clouds, not paths