chapter23filled in.ppt

CHEM 132 Layman chapter 23 CHEM 132 Layman chapter 23 CHEM 132 Layman chapter 23 Rutherford?s Experiment and Atomic Structure (1911) CHEM 132 Layman chapter 23 Atomic Structure Review Nucleons Neutrons Protons Electrons Nuclide X A Z CHEM 132 Layman chapter 23 Nuclear Stability Z = 83 (Bi) last stable nucleus CHEM 132 Layman chapter 23 Radioactive Decay Spontaneous Energy released higher energy ??? lower energy + radiation nuclide nuclide (excess energy) CHEM 132 Layman chapter 23 Alpha decay Modes of radioactive decay Emission: ? particle parent nuclide daughter nuclide ?A ?Z ?N CHEM 132 Layman chapter 23 Beta decay Modes of radioactive decay Emission: ? particle (an electron) ?A ?Z ?N CHEM 132 Layman chapter 23 Positron Emission Modes of radioactive decay Emission: ? particle (antiparticle of the electron) ?A ?Z ?N CHEM 132 Layman chapter 23 Electron Capture Modes of radioactive decay Emission: x-ray photon ?A ?Z ?N CHEM 132 Layman chapter 23 Gamma emission Modes of radioactive decay Emission: ?-ray (high energy photon, h?) Gamma only Other nuclear process ?A ?Z ?N CHEM 132 Layman chapter 23 Kinetics Review CHEM 132 Layman chapter 23 Decay Kinetics Decay rate = activity Half-life: time it takes for 1/2 of nuclei to decay generic 1st order rxn rate = k [X] ln ([Xo]/[X]) = kt ln[Xo/(Xo/2)] = kt1/2 t1/2 = (ln 2) / k = 0.693 / k CHEM 132 Layman chapter 23 Carbon from a cypress beam obtained from the tomb of an ancient Egyptian king gave 9.2 disintegrations min-1 of 14C per gram of carbon. 14C has a half-life of 5730 years. Living organisms have an activity of 15.3 d min-1 g-1. How old is the beam? CHEM 132 Layman chapter 23 Nuclear transmutation and element synthesis t1/2 = 0.9 s t1/2 = 1400 yr t1/2 = 1.38 d t1/2 = 27 min t1/2 = 3.1 min t1/2 = 1.7 s Glenn Seaborg 1911-1999 CHEM 132 Layman chapter 23 Mass and energy interconversion The total quantity of mass-energy in the universe is constant. chemical reaction H2O ? 2H + O ?E = 934 kJ/mol H2O ?m ~ 1.04 ? 10-8 g/mol H2O nuclear reaction 12C ? 6p + 6 n ?m ~ 0.099 g /mol 12C ?E = 8.89 ? 1012 kJ/mol (from nuclear binding energy) CHEM 132 Layman chapter 23 Nuclear Fission 2.1 ? 10+10 kJ mol-1