Lecture0510fa

Lecture0510fa - /08/09 1 Origin and Properties of the...

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Unformatted text preview: Chemistry 83 09/08/09 1 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 Kaiser, D. The Other Evolution Wars. American Scientist. 95. 520 Albert Einstein and Georges Lemaitre Lemaitre (1927) extended work of Einstein (1905), E = mc 2 . Church saw no conflict between religion and Big Bang hypothesis. He was appointed to bishop, later to head of the Pontifical Academy of Science at the Vatican, and finally to monsignor. “Big Bang” hypothesis was proposed by a Catholic priest Chemistry 83 09/08/09 2 Origin of Universe: Big Bang Theory • Big Bang (12 - 14 B years ago) - all matter and energy were at a point, then an explosion occurred followed by a continuous expansion • Theory based on observation by Hubble that the Universe is expanding • Validity unknown as with all theories • Utility – Explains expansion of Universe – Correctly predicted residual heat in Universe ~3 K (0 K = -273 o C = -459 o F) – Explains origin of the chemical elements Overview of the Origin of the Chemical Elements Big Bang 10 30 K 3 min 300,000-500000 yr Stars and Galaxies Nucleosynthesis - fusion in smaller stars for elements having Z ≤ 26, and neutron capture for elements having Z > 26 but only when stars >1.4 times greater in mass than our sun undergo a supernova H + , He 2+ ,e- 10 6 K (plasma) H, He 10 3 K (atoms) 12-13 billion yrs n + p + ; n → p + + e- 10 12 K 10-3 sec 1 billion yrs gravity Fusion reactions during Big Bang E = mc 2 Chemistry 83 09/08/09 2 Origin of Universe: Big Bang Theory • Big Bang (12 - 14 B years ago) - all matter and energy were at a point, then an explosion occurred followed by a continuous expansion • Theory based on observation by Hubble that the Universe is expanding • Validity unknown as with all theories • Utility – Explains expansion of Universe – Correctly predicted residual heat in Universe ~3 K (0 K = -273 o C = -459 o F) – Explains origin of the chemical elements Overview of the Origin of the Chemical Elements Big Bang 10 30 K 3 min 300,000-500000 yr Stars and Galaxies Nucleosynthesis - fusion in smaller stars for elements having Z ≤ 26, and neutron capture for elements having Z > 26 but only when stars >1.4 times greater in mass than our sun undergo a supernova H + , He 2+ ,e- 10 6 K (plasma) H, He 10 3 K (atoms) 12-13 billion yrs n + p + ; n → p + + e- 10 12 K 10-3 sec 1 billion yrs gravity Fusion reactions during Big Bang E = mc 2 Chemistry 83 09/08/09 3 H and He nuclides (nuclei) were formed during the Big Bang • During the Big Bang, energy converted to mass, E = mc 2 , where E is energy, m is mass of particles created, and c is velocity of light • Particles formed were p, n, and e in a plasma • 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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This note was uploaded on 12/19/2010 for the course CHEM 83 taught by Professor Bonk,j during the Fall '08 term at Duke.

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Lecture0510fa - /08/09 1 Origin and Properties of the...

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