History of the Atom

  • John Dalton

    John Dalton
    His theory of an atom was that they were small and had different masses.
    John figured out that elements can be determined by its atomic weight. His theories were put into a book called the " New System of Chemical Philosophy" around 1808.
  • JJ Thomson

    JJ Thomson
    He believed that the atom was positively charged and the electrons were embedded inside them.
    JJ had expiremented with the Cathode Ray Tube, to prove that rays are beams of energy with electrons that make up a ray. The electrons released from the atoms can become apart of a ray and what Thomson was trying to prove was that once apart of a ray the electrons can't be seperated from the ray.
    The tube showed a measured amount of energy that changed when a magnetic field was applied showing...
  • Thomson Cont.

    that the ray and electrons can't be seperated
  • Hantaro Nagoaka

    Hantaro Nagoaka
    Hantaro said that inside an atom is a positive sphere and that electrons are revolving around it. His Saturn-like model was the most accurate even though it came before Rutherford's and Thomson's.
    He recieved the award, " Order of Culture", which is recieved for the participation in Japan's literature, art, or culture in 1973.
    He was lead to believe that electrons would lose energy and eventually smash into the nucleus.
  • Ernest Rutherford

    Ernest Rutherford
    He believed that the atom is mostly empty space and that the electrons orbit around the nucleus as well.
    1897 during his first time at the Cavendish Laboratory, Rutherford found a way to detect electromagnetic waves by making his own invention. In 1908 he was also knighted into the New Year's Honours List.
  • Niels Bohr

    Niels Bohr
    His theory was that the electrons are in shells and randomly move around.
    In about 1901 Bohr stated that the electrons stay a fixed distance away from the nucleus and that when the atom absorbs energy that the electrons move farther away from the nucleus. Then later on recieved the Noble Prize in 1922.
  • G. N. Lewis

    G. N. Lewis
    1916 Lewis added that a chemical bond is a pair of electrons with two atoms.He had redefined an acid, being any atom or molecule with less than eight electrons in 1923.
    1940s worked on the photochemical proccess, meaning turning light into energy
  • James Chadwick

    James Chadwick
    James had then discovered the neutron, proving they exist in the atom.
    He and Rutherford decribed the neutron as a particle with mass but no charge. In 1919 he had focused on the study of radioactivity. and helped out with the making of nuclear bombs during world war two.