Atomic theory

  • Discovery of subatomic particles

    Atoms were thought to be the smallest possible division of matter until 1897 when J.J. Thomson discovered the electron
  • Disproved

    Thomson's plum pudding model was disproved in 1909
  • Gold foil experiment

    In the gold foil experiment, Hans Geiger and Ernest Marsden shot alpha particles at a thin sheet of gold, measuring their deflection with a fluorescent screen. a small fraction of the alpha particles experienced heavy deflection.This led Rutherford to propose a planetary model in which a cloud of electrons surrounded a small, compact nucleus of positive charge.
  • discovery of isotopes

    In 1913 radiochemist Frederick Soddy discovered that there seemed to be more than one element at each position on the periodic table. Then the isotope was discovered
  • Discovery of nuclear particles

    Rutherford concluded that the hydrogen nuclei emerged from the nuclei of the nitrogen atoms themselves.