atomic theory timeline

By karim sous
  • 400 BCE

    Democritus

    Democritus
    Democritus introduced the idea of the atom as the basic building block matter.

  • Dalton

    Dalton
    was the first complete attempt to describe all matter in terms of atoms and their properties.

  • Thomson

    Thomson
    the electron and then went on to propose a model for the structure of the atom.

  • Rutherford

    Rutherford
    the discovery that atoms contain a positively charged nucleus much smaller than the actual atom.

  • Niels Bohr

    Niels Bohr
    in which he proposed that energy levels of electrons are discrete and that the electrons revolve in stable orbits around the atomic nucleus but can jump from one energy level (or orbit) to another.

  • James Chadwick

    James Chadwick
    made a fundamental discovery in the domain of nuclear science: he proved the existence of neutrons – elementary particles devoid of any electrical charge.