Atomic structure

History of Atomic Structure

By eache10
  • 400

    Democritus, c470-370 BC, GREECE

    Democritus, c470-370 BC, GREECE
    Democritus was a Greek philosopher/scientist. He made a significant contribution with his atomic theory of the universe: all things originate from a vortex of tiny, indivisible particles, which he called atoms. Atomism - the theory that suggested that the natural world consisted of two essential (and opposite) invisible bodies – atoms and void (nothingness).
    wikipedia atomos – Greek – means uncuttable.
  • Sir Isaac Newton, 1643-1727, ENGLAND

    Sir Isaac Newton, 1643-1727, ENGLAND
    Newton proposed a mechanical universe with small solid masses constantly in motion. He suggested that atoms were held together by forces/attractions. wikipedia note: all images are from Wikipedia. (Thanks)
  • John Dalton, 1766-1844, ENGLAND

    John Dalton, 1766-1844, ENGLAND
    Dalton explained that chemical combination is based on the interaction of atoms of definite and characteristic WEIGHT. Proposed an "atomic theory" with spherical solid atoms based upon measurable properties of mass. When atoms combine to form a particular compound, they always combine in the same ratios by weight.
  • Dmitri Mendeleev, 1834-1907, RUSSIA

    Dmitri Mendeleev, 1834-1907, RUSSIA
    He is credited as being the creator of the first version of the periodic table of elements. Using the table, he predicted the properties of elements yet to be discovered. He attempted to classify the elements according to their chemical properties and he noticed patterns that led him to his Periodic Table.
  • George Johnston Stoney, 1826-1911, IRELAND

    George Johnston Stoney, 1826-1911, IRELAND
    Stoney introduced the ELECTRON as "the fundamental unit quantity of electricity." One of the most important works he made was the conception and calculation of the magnitude of the "atom of electricity."
  • Sir Joseph John Thomson, 1856-1940, ENGLAND

    Sir Joseph John Thomson, 1856-1940, ENGLAND
    Thomson discovered the electron. (He won a Nobel Prize for Physics in 1906 for discovering the electron and for his work on the conduction of electricity in gases.) He proposed that electricity was made of discrete negative particles he called electrons.
  • Max Planck, 1858-1947, GERMANY

    Max Planck, 1858-1947, GERMANY
    Max Planck was considered to be the founder of Quantum Physics, which is a branch of physics providing a mathematical description of much of the wave-like behavior and interactions of energy and matter. In the mid-1920s, developments in quantum mechanics quickly led to its becoming the standard formulation for atomic physics.
  • Hantaro Nagaoka, 1865-1950, JAPAN

    Hantaro Nagaoka, 1865-1950, JAPAN
    Nagaoka developed an early, incorrect "planetary model" of the atom. The model was based around an analogy to the explanation of the stability of the Saturn rings (the rings are stable because the planet they orbit is very, very massive). Two predictions made from the model were a very massive nucleus (a very massive planet) and electrons revolving around the nucleus, bound by electrostatic forces (the rings revolving around Saturn, bound by gravitational forces).
  • Robert A. Millikan, 1868-1953, AMERICA

    Robert A. Millikan, 1868-1953, AMERICA
    Oil drop experiment determined the charge (e=1.602 x 10 -19 coulomb) and the mass (m = 9.11 x 10 -28 gram) of an electron.
  • Ernest Rutherford, 1871-1937, BRITAIN/NEW ZEALAND

    Ernest Rutherford, 1871-1937, BRITAIN/NEW ZEALAND
    Rutherford is known as the "Father of Nuclear Physics." He won a Nobel Prize for Chemistry and this is because he discovered the concept of radioactive half-life, His most well-known achievement was when he maintained that atoms have their positive charge concentrated in a very small nucleus, and thus made the Rutherford model of the atom, through his discovery and interpretation of Rutherford scattering in his gold foil experiment.
  • Henry G-J Moseley, 1887-1915, ENGLAND

    Henry G-J Moseley, 1887-1915, ENGLAND
    Moseley's contribution to atomic physics was the justification from physical laws of the previous chemical concept of the atomic number. Before Moseley's Law, atomic numbers were thought to have just put the elements in a neat sort of order. However, since Moseley's Law, our understanding of the atom and its atomic number has improved; we now know that atomic numbers have a strong physical basis.
  • Niels Bohr, 1885-1962, DENMARK

    Niels Bohr, 1885-1962, DENMARK
    The Bohr model of the atom, the theory that electrons travel in discrete orbits around the atom's nucleus and the shell model of the atom, where the chemical properties of an element are determined by the electrons in the outermost orbit were achieved by Bohr, who received a Nobel Prize for physics in 1922.
  • Sir James Chadwick, 1891-1974, ENGLAND

    Sir James Chadwick, 1891-1974, ENGLAND
    Chadwick won a Nobel Prize for his discovery of a neutral atomic particle of the nucleus which had similar mass to the proton. This was the NEUTRON. Chadwick’s discovery made it possible to create elements heavier than uranium in the laboratory.