Atomic Theory Timeline

  • Democritus
    440 BCE

    Democritus

    Atoms are "uncut-able"
    Atoms are small, hard particles
    Atoms constantly move
  • Period: 440 BCE to

    Atomic Theory Timeline

  • Democratus Atom Model
    440

    Democratus Atom Model

  • 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
  • John Dalton Atomic Model

    John Dalton 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
  • J.J. Thomson atomic model

    J.J. Thomson 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
  • Ernest Rutherford atomic model

    Ernest Rutherford atomic model

  • Niels Bohr

    Niels Bohr

    Electrons jump between levels from path to path
    Electrons travel in definite paths
  • Niels Bohr Atomic Theory

    Niels Bohr Atomic Theory

  • Erwin Schrodinger and Werner Heisenberg

    Erwin Schrodinger and Werner Heisenberg

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

    Erwin Schrodinger and Werner Heisenberg Atom Model