Physics Lecture 17

Physics Lecture 17 - i There is none There must be energy...

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I. A. What is wrong with the Rutherford model? 1. Orbiting electrons emit EM waves classically 2. Electron will lose energy and spiral into nucleus B. Discrete Spectra coming from atoms II. Bohr Model and spectra A. Electrons only have certain quantized energies 1. E n = -13.6eV/n 2 (ONLY FOR HYDROGEN)**** B. Emission transition between levels 1. E ph = |ΔE transition | C. Types of Transition 1. Lyman Series – light emitted when electron drops to n=1 state 2. Balmer Series – light emitted when electron drops to n=2 state 3. Paschen Series – light emitted when electron drops to n=3 state a. Example: An electron in n=4 state drops to the n=2 state. What is the frequency for this transition? i. E 4 = -13.6eV/4 2 = -.85 eV ii. E 2 = -13.6eV/2 2 = -3.40 eV iii. E ph = |ΔE transition | = 2.55 eV iv. E ph = hf f = E ph /h = 6.16 x 10 14 Hz b. Example: An electron is initially in n=2 state, then jumps up to the n=4 state. What Is the frequency of the emitted light for this transition?
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Unformatted text preview: i. There is none. There must be energy lost for emission ii. absorption is required to go from lower to higher energy III. Atom & Probability A. 3-D Probability density |ψ| 2 prob/m 3 1. Total Probability |ψ| 2 *ΔV 2. Prob{shell} = |ψ| 2 *(surface area)*(Δr) a. Small Δr = dr (then take integral) i. Prob = integral(|ψ| 2 *(surface area) dr) b. Example: total probability = 1 i. Since ψ is constant |ψ| 2 *ΔV = A 2 4/3 πr 2 = 1 1. A = sqrt(3/4πr 2 ) 2. Probability = integral of P(r)dr A = sqrt(3/4πr 2 ) IV. Fluorescence A. Illuminate with one color and emits at different colors 1. Photons jump several energy levels due to a high energy photon a. Smaller downward jumps lower energy photons Bohr Model for Hydrogen E n = -13.6eV/n 2 (ONLY FOR HYDROGEN) E ph = |ΔE transition | 3-D Probability Distributions Radial probability distribution function P(r) = P r = 4πr 2 |ψ| 2...
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This note was uploaded on 04/07/2008 for the course PHYS 212 taught by Professor Ladd during the Spring '08 term at Bucknell.

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