EPS C82 Final: EPS C82 Final
13 Dec 2017
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Lecture 2: origins of water & basic earth history. Origin of solar system & planet - solar nebular theory. Elements: 118 known, 20 artificial, 98 natural. Of all visible matter in universe, 75% hydrogen (a1), 23% helium (a2), 2% H and some he formed just after the big bang (13. 8 b years ago) heavier elements that dominate in us and our planet. Isotopes of an element can have zero or more neutrons in the nucleus. Hydrogen isotopes: protium (1p), deuterium (1p1n), tritium (1p2n, good. Helium-3 has 2 protons and 1 neutron/ -4 2 protons and 2 neutrals tracer) - p and d stable, t radioactive. Heavier e formed in stars (up to oxygen 16) in our sun, fe/iron-56 in massive stars) - stellar nucleosynthesis. Heavier elements are formed from fusion of lighter elements (which also releases energy), up to iron. Very heavy elements form in supernova explosions - supernova nucleosynthesis (1) produced by earlier generations of stars.
