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Atomic Physics. Micro-world Macro-world Lecture 15. Dimitri Mendeleev. Periodic table of elements. Elements in vertical rows have similar chemical properties. Inert gases. Schroedinger’s Equation for multi-electron Atoms. -. -. -. +. -. -.
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Atomic Physics Micro-world Macro-world Lecture 15 Dimitri Mendeleev
Periodic table of elements Elements in vertical rows have similar chemical properties Inert gases
Schroedinger’s Equation for multi-electron Atoms - - - + - -
Solutions give energy levels that are clustered in “shells” n # of states - - - - 1 2 - - 2 8 - - - 3a 8 + 3b 10 - - - - - - 4a 8 - 4b 10 4c 14 - -
Pauli exclusion principle Wolfgang Pauli Only one electron per quantum state Once a quantum state is occupied additional electrons are excluded
Light elements - +2 +1 - - outermost shell is full 1 electron in outermost shell Helium Hydrogen - - - - - - - +3 +10 - - - - - - Neon Lithium
Periodic table of elements Elements in vertical rows have similar chemical properties 1 e- in outer shell Filled outer shell
Chemical properties depend upon the outermost shell configuration - - - - - - - - - - - +8 - - - - +16 - - - - - - - Oxygen Outermost shells Have 2 vacancies - - Sulfur
Periodic table of elements 2 vacancies in outer shell
Atoms combine to form molecules by filling outer shells +1 Hydrogen - - - Water=H2O - - +8 - - - - - Hydrogen +1 Oxygen
Atoms combine to form molecules by filling outer shells Hydrogen Hydrogen +1 - - +1 - - - Methane=CH4 +6 - - - - - +1 +1 Carbon Hydrogen Hydrogen
Elements with full outer shells don’t form molecules - - - - - - - - - - - - - - +2 - +10 +18 - - - - - - - - - - Helium - - - Neon - - Noble gasses Argon
Periodic table revisited Elements in vertical rows have same outer shell configurations 1 elec in outer shell 2 vacancies in outer shell 4 e- in outer shell Outer shell is full
Spectra are atomic “signatures” Hydrogen Mercury Neon
Decoding atomic spectra Mercury spectrum “quantum jump” photon Ephoton=E2-E1 quantum energies quantum orbits Mercury energy levels
1924 Otto Laporte Allowed quantum states are either even or odd Laport rule odd Otto Laporte 1902-1971 even even even even odd odd odd even odd OK odd even not allowed even X even odd X odd
Laporte rule is a consequence ofLeft-Right symmetry of Nature Left Right symmetry = “Parity” symmetry Eugene Wigner 1902-1995 Eugene Wigner 1902-1995 1963 Nobel Physics prize “for the discovery and application of fundamental symmetry principles”
P = Parity = L R/R L Field (& rules) of football are parity symmetric Rules of baseball are not parity symmetric
Even & Odd quantum functions Even Function Odd Function LR RL LR RL Does not change Changes sign Parity = +1 Parity = -1
Parity Conservation in QM Left Right symmetry of Nature Conservation of Parity photon has P=-1 even state initially: even state (Peven=+1) finally: odd state+ (Podd=-1) Photon (Pphot=-1) odd state Pinitial=+1 Pfinal=(-1)(-1)=+1 Parity is conserved
Atomic red shifts V=0.25c=75,000km/s l shift = 25% V=0.05c=15,000km/s l shift= 5% V=0.01c=3,000km/s l shift = 1%
Laser – Light Amplification by Stimulated Emission of Radiation – Example: Helium-Neon Laser Cartoon: sealed container I I I Helium-Neon gas mixture mirror “partial” mirror + - Helium-Neon Laser in real life Power source
Laser – Light Amplification by Stimulated Emission of Radiation – “Pump” → Ne* → → “meta-stable” states Ne* → → → Ne* → → Ne* → → → Stimulates emission Ne* → Exactly in phase → → Ne* → Exactly in phase Exactly in phase