History of the Atom

  • 355


    Aristotle defined motion as the actuality of a potentiality as such.[23] Aquinas suggested that the passage be understood literally; that motion can indeed be understood as the active fulfillment of a potential, as a transition toward a potentially possible state
  • 460


    The theory of Democritus held that everything is composed of "atoms", which are physically, but not geometrically, indivisible; that between atoms lies empty space; that atoms are indestructible; have always been, and always will be, in motion; that there are an infinite number of atoms, and kinds of atoms, which differ in shape, and size. Of the mass of atoms, Democritus said "The more any indivisible exceeds, the heavier it is." But his exact position on weight of atoms is disput
  • Antoine Lavoisier

    Lavoisier investigated the composition of water and air, which at the time were considered elements. He determined that the components of water were oxygen and hydrogen, and that air was a mixture of gases, primarily nitrogen and oxygen.
  • John Dalton

    Dalton's atomic theory:
    1.Elements are made of extremely small particles called atoms.
    2.Atoms of a given element are identical in size, mass, and other properties; atoms of different elements differ in size, mass, and other properties.
    3.Atoms cannot be subdivided, created, or destroyed.
    4.Atoms of different elements combine in simple whole-number ratios to form chemical compounds.
    5.In chemical reactions, atoms are combined, separated, or rearranged.
  • Marie and Pierre Curie

    Marie discovered that thorium gives off the same rays as uranium. Her continued systematic studies of the various chemical compounds gave the surprising result that the strength of the radiation did not depend on the compound that was being studied.
  • Henry Becquerel

    His work was concerned with the plane polarization of light, with the phenomenon of phosphorescence and with the absorption of light by crystals. Won nobel prize of physics in 1903
  • J.J. Thompson

    As the cathode rays carry a charge of negative electricity, are deflected by an electrostatic force as if they were negatively electrified, and are acted on by a magnetic force in just the way in which this force would act on a negatively electrified body moving along the path of these rays, I can see no escape from the conclusion that they are charges of negative electricity carried by particles of matter.
    —J. J. Thomson
  • Ernest Rutherford

    Rutherford's researches, in New Zealand, were concerned with the magnetic properties of iron exposed to high-frequency oscillations, and his thesis was entitled Magnetization of Iron by High-Frequency Discharges. He was one of the first to design highly original experiments with high-frequency, alternating currents
  • Henry Mosely

    Henry Moseley was an English physicist. Moseley's outstanding contribution to the science of physics was the justification from physical laws of the previous empirical and chemical concept of the atomic number. He won the nobel prize in 1916
  • Max Planck

    Was a German physicist who is regarded as the founder of the quantum theory, for which he received the Nobel Prize in Physics in 1918.Planck expected that wave mechanics would soon render quantum theory—his own child—unnecessary. This was not to be the case, however. Further work only cemented quantum theory, even against his and Einstein's philosophical revulsions. Planck experienced the truth of his own earlier observation from his struggle with the older views in his younger years.
  • Niles Bohr

    Danish physicist who made fundamental contributions to understanding atomic structure and quantum mechanics, for which he received the Nobel Prize in Physics in 1922.[1] Bohr mentored and collaborated with many of the top physicists of the century at his institute in Copenhagen.
  • Robert Millikan

    Millikan made numerous momentous discoveries, chiefly in the fields of electricity, optics, and molecular physics. His major success was the accurate determination of the charge carried by an electron, using the elegant "falling-drop method"; he also proved that this quantity was a constant for all electrons (1910), thus demonstrating the atomic structure of electricity. Won the Nobel Peace Prize for physics in 1923
  • Werner Heisenberg

    In 1928, the British mathematical physicist P. A. M. Dirac had derived the relativistic wave equation of quantum mechanics, which implied the existence of positive electrons, later to be named positrons
  • James Chadwick

    He made a fundamental discovery in the domain of nuclear science:e proved the existence of neutrons - elementary particles devoid of any electrical charge
  • Erwin Schrodinger

    Erwin Rudolf Josef Alexander Schrödinger was an Austrian physicist and theoretical biologist who was one of the fathers of quantum mechanics, and is famed for a number of important contributions to physics, especially the Schrödinger equation, for which he received the Nobel Prize in Physics in 1933. In 1935, after extensive correspondence with personal friend Albert Einstein, he proposed the Schrödinger's cat