The Atom

By tboot5
  • Period: to


    Alchemists - 500 BC-1720
    Ancient art practice especially in the Middle Ages, devoted
    chiefly to discovering a substance that would transmute the more
    common metals into gold or silver, and to finding a means of
    indefinitely prolonging human life. Although its purposes and
    techniques were often illusory, alchemy was in many ways the
    predecessor of modern science, especially chemistry.
    Democritus - 442 BC
    Postulated the theory of atoms and void; the universe is made
    up of empty space and a nearly
  • Democritus - 442 BC

    Postulated the theory of atoms and void; the universe is madeup of empty space and a nearly infinite number or invisibleparticles differing in arrangement, form, and position. Hestated that all all matter is composed of indivisible atoms.
  • John Dalton - 1803

    English chemist who proposed the Atomic Theory which
    stated that all matter was composed of small indivisible
    particles called atoms. These atoms possess unique
    characteristics and weight for different elembets.
    He also stated that three types of atoms exist: simple
    (elements), compound (simple molecules), and complex
    (complex molecules).
  • J.J. Thomson - 1898

    First to measure the electron. Developed the
    plum-pudding model of the atom. Describes the atom as a
    slightly positive sphere with small electrons inside.
  • Ernest Rutherford - 1909-1911

    Inferred a small, dense, positively-charged nucleus as theresult of the alpha particle scattering gold foil experiment.
  • Neils Bohr - 1913

    A Danish physicist who stated that electrons could only
    orbit the nucleus in succesively larger orbits around the
    nucleus. The outer orbits could hold more electrons. The
    electrons in the outermost shell determine the properties of
    the atom. He also inferred that when an electron moves from
    an outer orbit to an inner orbit it emits a quantum of energy,
    a photon, in the form of light.
  • Erwin Schroedinger - 1926

    Developed wave mechanics which describe the behavior
    of quantum systems for bosons.
  • Chadwick - 1931

    Discovered the neutron.