History of an atom

  • Oct 29, 1000


    Proposed that everything id msde up of small particles and called them "Atoms".
    "By convention bitter, by cinvention sweet, but in reality atoms and void."
  • John Dalton

    John Dalton
    Proposed an "atomic theory" with spherical solid atoms based upon measurable properties of mass.
  • Eugen Goldstein

    Eugen Goldstein
    Used a CRT to study "canal rays" which had electrical and magnetic properties opposite of an electron
  • J.J Thomson

    J.J Thomson
    Used a CRT to experiment determine the charge to mass ratio (e/m) of an electron=1.759*10^8 columbs/gram. Studied "canal rays"
    Model called "plum pudding"
  • Ernest Rutherford

    Ernest Rutherford
    Proposed that the atom has a central positive nucleus surrounded by negative orbiting electrons, that most of the mass of the atom was contained in the small nucleus, and that the rest of the atom was mostly empty space that has enough positive charge to account for the great deflection of some of the alpha particles
  • Niels Bohr

    Niels Bohr
    Proposed that electrons travel in specific circular paths, or orbit, orbits around the nucleus defined by their angular momentum
  • Robert Millikan

    Robert Millikan
    From 1908-1917 He carried out experiments (oil-drop experiment) to find the quantity of charge carried by an electron. Using that value and the charge-to-mass ratio (Thomson), he calculated the mass of the eletron.
    Mass= 1/1840 the mass of a hydrogen atom.
  • James Chadwick

    James Chadwick
    Confirmed the existence of neutrons which have no charge. Atomic nulei contain neutrons and positively charged protons
  • Erwin Schrodinger

    Erwin Schrodinger
    Developed mathematical equations to describe the motion of electrons in atoms. Also, he stated that electrons behave in a wave-like manner rather than just as particles and that their exact location within an orbit could not be precisely calculated.