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Atomic Model Timeline

  • The Alchemists
    500 BCE

    The Alchemists

    Discovered a substance that transformed common metals into silver or gold as well as making a basic version of the periodic table.
  • Plato
    428 BCE

    Plato

    Came up with the idea of elements.
  • Democritus
    400 BCE

    Democritus

    Proposed the existence of atoms.
  • Robert Boyle

    Robert Boyle

    Discusses the possibility of atoms existing.
  • Atone Lavoisier

    Atone Lavoisier

    Proved the Law of Conservation of Matter.
  • John Dalton

    John Dalton

    Proposed that compounds were multiple atoms combined together.
  • Billiard Ball Model

    Billiard Ball Model

    Proposed by John Dalton. Earliest model of an atom and therefore very simple.
  • Amedeo Avagadro

    Amedeo Avagadro

    Realized that elements could exist as molecules.
  • JJ Thompson

    JJ Thompson

    Determined the charge to mass ratio for electrons.
  • Dmitri Mendeleev

    Dmitri Mendeleev

    Created the modern periodic table.
  • Pierre and Marie Curie

    Pierre and Marie Curie

    Did lots of research into radioactive elements and substances.
  • Plum Pudding Model

    Plum Pudding Model

    Proposed by JJ Thompson. Electrons surrounded by a positive charge.
  • Albert Einstein

    Albert Einstein

    Stated the equivalence of energy and mass as well as proposing the quantum of light.
  • Robert Millikan

    Robert Millikan

    Discovered the negative charge of an electron.
  • Ernest Rutherford

    Ernest Rutherford

    Concluded the nucleus has a positive charge.
  • Solar System Model

    Solar System Model

    Proposed by Ernest Rutherford. An earlier version of the electron cloud model.
  • Neils Bohr

    Neils Bohr

    Proposed that the outer orbit of an atom could hold more electrons.
  • Henry G. J. Mosley

    Henry G. J. Mosley

    Discovered the number of protons in an element and redefined the atomic number.
  • Werner Heisenberg

    Werner Heisenberg

    Stated the Uncertainty Principle, one of the foundations of quantum mechanics.
  • Electron Cloud Model

    Electron Cloud Model

    Proposed by Erwin Schrodinger and Werner Heisenberg. A nucleus surrounded by quickly moving electrons.
  • James Chadwick

    James Chadwick

    Discovered Neutrons.
  • Erwin Schrodinger

    Erwin Schrodinger

    Made the Schrodinger's cat thought experiment, forming the basics for quantum mechanics.