History of the Atom

By 23klovasow
  • 460 BCE

    Democritus

    Democritus
    suggested the original atomic theory. Model was an indestructible spheres.

  • John Dalton

    John Dalton
    Introduced Atomic theory into chemistry. His theory was that everything is made of atoms, and that atoms of the same element are identical. He also said that atoms combine in whole numbers. Told us that in chemical reactions, atoms are never changed but can be seperated, combined, or rearanged. His atomic model was a sphere that when added to other spheres increased its weight.

  • Dmitri Mendeleev

    Dmitri Mendeleev
    Formulated the very first rudimentary version of the periodic table based on atomic weight.

  • Eugen Goldstein

    Eugen Goldstein
    Discovered Protons by studying cathode rays.

  • J.J. Thompson

    J.J. Thompson
    First to discover electrons. He found them by studying cathode ray tubes. His model is a sphere composed of electrons called the "plum pudding model".

  • Robert Millikan

    Robert Millikan
    Experimented to find out the electric charge carried by a single electron.

  • Niels Bohr

    Niels Bohr
    Created the first model where electrons orbit all around the atom.

  • Ernest Rutherford

    Ernest Rutherford
    Hypothesized that atoms have their charge in a very small nucleus. He was also the first person to create an artificial nuclear reaction. His model includes a nucleus being orbited by electrons.

  • James Chadwick

    James Chadwick
    Credited with discovering the neutron while studying under Ernest Rutherford. His atomic model includes protons and neutrons being orbited by electrons.