09 - 2 m e e 4 /h 2 (E(n) are called energy levels) n = 1...

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Lecture 9 => Review of Lecture 8: Planck proposes that the vibrational energy in heated solids is quantized (not continuous) =>E vib = nh ν .Then can predict entire black body radiation curve, if h has the value 6.62 x 10 34 J s Photoelectric effect: Einstein proposes new concept to explain experiments. Light energy comes in bundles (now called photons) ε ph = h ν . Photons are absorbed one at a time and if ν > ν crit then electrons can be ejected from a metal. Ionization energy (work function) is the minimum energy required to do so (h ν crit ). Neils Bohr, using a simple planetary like model of the atom, proposes that the angular momentum of electrons “orbiting” the nucleus in hydrogen like atoms is quantized: m e rv = nh. Then can calculate the binding energy of one electron to a nucleus of charge +Ze:
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E(n) = R H Z 2 /n 2 where R H = 2.179 x 10 18 J = 4
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Unformatted text preview: 2 m e e 4 /h 2 (E(n) are called energy levels) n = 1 is the ground state. n > 1 are excited states. Electrons in atoms can absorb energy only in specific increments. Input energy can be from a photon or from sufficiently energetic collisions with hot atoms or electrons in a discharge (from a large applied voltage). Excited state electrons eventually relax to the ground state (some times in multiple steps), emitting photons to conserve energy. Lyman, Balmer, Paschen, series. Changing energy level by interaction with light: E = E(n initial ) E(n final ), if + photon emitted, if photon absorbed. 2 These could represent 2 or 2 2 One radial node and one angular ( = 90 o ) node One radial node and two angular ( = 90 o ) nodes All show...
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09 - 2 m e e 4 /h 2 (E(n) are called energy levels) n = 1...

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