07-Standard_Model - Layersof Reality Biology190A Lecture7...

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Layers of Reality Biology 190A Lecture 7 ‐‐‐ Prof. Steve Schneider Dept. of Astronomy
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What is in the esto? Pesto? 1) Basil, garlic, nuts, oil … 2) Chlorophyll, cellulose, acids … 3) Carbon, hydrogen, oxygen … 4) Neutrons, protons, electrons. . ) Quarks and uons 5) Quarks and gluons
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Periodic Table of the Elements Dimitri Mendeleev (1869) listed the known elements in order of mass, lined up according to chemical properties—the Periodic Table.
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Henri Becquerel and the Discovery of Radioactivity (1896) Uranium salts emit some kind of “ray” at exposes photographic plates Marie that exposes photographic plates. Marie & Pierre Curie helped to investigate this henomenon further. 1903 phenomenon further. Becquerel’s Photographic Plate That Led Him to the Discovery of Radioactivity
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935 Discoveries of the 1935 Proton and the Neutron utherford Chadwick (1919) Ernest Rutherford found that heavy nuclei lease hydrogen nuclei (protons) Rutherford release hydrogen nuclei (protons). (1932) James Chadwick discovers a particle almost entical to a proton but with no electric charge identical to a proton, but with no electric charge (or neutral)—therefore named a “neutron” Atoms contain both in their nuclei, although only the protons determine the chemical properties.
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The Structure of the Atom and Two New Forces By the 1930s, the fundamental structure of matter seemed to be nderstood Matter is made of understood. Matter is made of atoms which are in turn composed f just 3 particles: electrons, o just 3 pa t c es eecto s, protons, and neutrons. There must be a force stronger than electric repulsion of protons to hold the nucleus together: the strong force There must be a much weaker force that causes the rare radioactive decays of some nuclei: the weak force
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Nuclear Fission ith too many neutrons nuclei undergo With too many neutrons, nuclei undergo fission. For example, the Uranium “236” isotope (92 protons and 144 neutrons).
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This note was uploaded on 11/22/2011 for the course BIOLOGY 190a taught by Professor Staff during the Fall '11 term at UMass (Amherst).

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07-Standard_Model - Layersof Reality Biology190A Lecture7...

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