History Of Atom

  • 370


    Matter is made of small indivisible particles which have different form, position and arrangement. Democritus named these particles atoms.
  • John Dalton

    John Dalton
    Developed an atomic theory stating that spherical atoms had measurable properties of mass
  • Goldstein

    Used cathode ray tubes to discover that “canal rays” have opposite properties of electron.
  • J.J Thomson

    J.J Thomson
    Discovers the electron and used cathode ray tubes to determine the charge to mass ratio of an electron to be 1.759 x 10^8 Coulombs/gram.
    Found canal rays were associated with a proton, H+.
  • Ernest Rutherord

    Ernest Rutherord
    Performed the gold foil experiment to determine that the nucleus is a small, dense, and positively charged part of the atom, based on the assumption that electrons are on the outside of the nucleus. Develops the plum pudding model of the atom.
  • Robert Millikan

    Robert Millikan
    Performed an oil drop experiment to determine the charge and the mass of an electron to be 1.602 x 10^-19 C and 9.11 x 10^-28 g respectively.
  • Neils Bohr

    Neils Bohr
    Publishes paper regarding combining nuclear and quantum theories.
    Created a model of successive orbital shells based o an equation of fixed radii and quantum numbers.
  • Erwin Schrodinger

    Erwin Schrodinger
    Saw electrons as a continuous cloud and developed wave mechanics to be a mathematical model for the atom.
  • James Chadwick

    James Chadwick
    Discovered neutral atomic particle with similar mass to a proton, the neutron by using alpha particles.