Class03OLD

Class03OLD - Origin and Properties of the Chemical Elements...

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Origin and Properties of the Chemical Elements The study of the origin, evolution and ultimate fate of the universe is part of the discipline of cosmology
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Kaiser, D. The Other Evolution Wars. American Scientist. 95. 520 Albert Einstein and Georges Lemaitre Lemaitre (1927) extended work of Einstein (1905), E = mc2. Church saw no conflict between religion and Big Bang hypothesis. Pope appointed him to bishop, later to head of the Pontifical Academy of Science at the Vatican, and later to monsignor. “Big Bang” hypothesis was proposed by a Catholic priest
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Origin of Universe: Big Bang Theory Among other observations, this theory based on the observation by Hubble that the Universe is expanding continuously Theory: 12 - 14 B years ago all matter and energy were at a point, then a massive explosion (Big Bang) occurred followed by a continuous expansion of the Universe Validity unknown as with all theories Utility Explains expansion of Universe Correctly predicted residual heat in Universe ~3 K (0 K = -273 oC = -459 oF)
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H and He nuclides (nuclei) were formed during the Big Bang During the Big Bang, energy converted to mass, E = mc2 , where E is energy, m is mass of particles created, and c is velocity of light Particles formed were p, n, and e Reactions were limited since n decay rapidly, n p + e, and temperature quickly fell below that needed for nuclear reactions to occur Some n and p reacted to form H-2, He-3, He-4 nuclides, but atoms could not form at that high T
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http://www.plasmas.org/E-4phases2.jpg Fourth State of Matter - Plasma http://www.ipp.mpg.de/BB/Kernfusion/fig5.gif Heat Cool
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Particles are represented by symbols M where Y is symbol for particle, C is charge, M is mass Alpha Proton p or H-1 Deuteron D or H-2 Electron - or e- Positron + or e+ Neutron n Name Symbol Other Nuclei of atoms (nuclides): ZX, Other particles: CY, A 2 4 He 1 1 H 1 2 H - 1 0 e + 1 0 e 0 1 n
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Nuclear changes are represented symbolically by nuclear equations First write the skeleton equation - translation of a fact into symbols Fact : protons combine at high temperature to produce H-2 and a positron. Skeleton equation : Insert plus signs between symbols of particles originally present (reactants) and particles finally present (products) and then insert an arrow between reactants and products 1 1 H ® 1 2 H + 1 0 e
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Balance equation : insert coefficients to make sums of mass numbers, A, and sums of charge numbers, Z, equal for reactants and products Equation: http://wine1.sb.fsu.edu/chm1046/notes/Nucleo/Nucleo.htm Fact: Fusion of H-2 produces He-4 Answer on slide 32 Fact: Fusion of H-1 produces He-4 and positrons Answer on slide 32 Practice: write nuclear equations for the following: 2 1 1 H ® 1 2 H + 1 0 e
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0 Energy E n e r g y l a s d Distance Repulsion Attraction Attraction due to nuclear “strong force” 2 H-1 H-2 + positron 107 K Repulsion due to like charges - electromagnetic force Fusion of H-1 is very exothermic, but requires a very high temperature to initiate the
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Class03OLD - Origin and Properties of the Chemical Elements...

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