Atomic Theory Timeline

  • 400


    Democritus said that all things are made of atoms.
  • John Dalon

    John Dalon
    John Dalton proposed an "atomic theory"with sqherical solid atoms based on measurable properties of mass.
  • Heinrich Hertz

    Hertz discovered radio waves
  • J.J Thompson

    J.J Thompson discovered the eloctron. He created an atom model as a sphere of positive matter in which electrons are positive by electronic forces.
  • Ernest Rutherford

    Rutherford discovered alpha and beta rays. He also identified alpha particles as helium nuclei. He also assumed that the electrons were outside the nucleus of the atom.
  • Neils Bohr

    Neils Bohr
    Bohr created a picture of an atomic structure. This model depicted both neutrons and protons in the nucleus. It also showed electrons in an electron cloud outside the nucleus.
  • James Chadwick

    James Chadwick
    James Chadwick discovered the neutron.
  • Cockroff and Walden

    Cockroff and Walden discovered that the atom can be split.
  • Atomic Bomb

    In 1945 an atomic bomb was dropped on Japan ending World War 2.
  • Nuclear Energy

    Neils Bohr developed the theory of nuclear fission. Because of these discoveries. we have power plants today.
  • Radio waves

    Hertz discoveries allowed advances in technology such as television, radio, and many other things.