History of the Atom

  • Jan 1, 1000


    Democritius discoadeverd matter is made of small indiviual paricles which have different forms postions and arrangements, which he named atoms.
  • John Dalton

    John Dalton
    Dalton developed the atom theory, stating that spherial atom have measured propertied of mass. He also develped the concept of moles.
  • Goldstein

    Goldstein discoverd canal rays which are postively charged equal to an atom.
  • J.J Thompson

    J.J Thompson
    Thompson discoverd the negatively charged electron in the cathode ray tube. He datermined that the electron was a component of all matter and calculated the charge to mass ratio for the electron. It is e/m= 1.76 x 10^8 coulombs/grams. He also discover protons are too associated with canal rays.
  • Robert Millikan

    Robert Millikan
    Millikan determined the unit charge of an electron by performing an oil-drop experiment. The formula is e+ 1.60 x 10^-19 coulombs.
  • Ernest Rutherford

    Ernest Rutherford
    Rutherford found that an atom has a small, dense, postively charged nucleus, and that the electrons move around the nucleus.
  • Neils Bohr

    Neils Bohr
    Bohr discovered how electrons move in a circular orbit at a fixed distance from the nucleus.
  • Erwin Schrodinger

    Erwin Schrodinger
    Schrodinger developed a mathematical equation to describe the motion of electrons in atoms. His work leads to the electron cloud model.
  • James Chadwick

    James Chadwick
    Chadwick confirmed the extistance of neutrons which have no charge Atomic nucluei contain neutrons and postively chraged protons.