Chem 1061 1st Edition Lecture 18Outline of Last Lecture 1. Definitionsa. Heat of Formationb. Heat of Combustionc. Heat of Vaporizationd. Heat of Fusion2. Determining Heat of Reactions from Heat of Formation3. Quantum Theory and Atomic Structurea. Definitions4. Electromagnetic RadiationOutline of Current Lecture 5. Calculating Frequency6. Quantum Theory7. Rydberg Equation8. Atomic Model9. Bohr’s Model10. Bohr’s Model of the Hydrogen AtomCurrent LectureCalculating FrequencyCalculate the Frequency of LiCl emission at 680 nm3.00 x 10^8 m/s = 680 nm x V3.00 x 10^8 m/s = 6.8 x 10^-7 m x V(3.00 x 10^8 m/s )/6.80 x 10^-7 m = 4.41 x 10^14 HzParticle Nature of Light: experimental evidence on p.291-293Quantum TheoryQuantum: a fixed amountE=h x V These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.E= Energy of a photon (packet of light energy)h= planks constant (6.626 x 10^-34 Js)V= frequencyCalculate the Energy Associated with Violet Light (λ=400 nm)Red Light (λ=700nm)E=hc/λViolet:E=(6.626 x 10^-34 Js)(3.00 x 10^8 m/s) / (4.00 x 10^-7m) = 4.97 x 10^-19 JRed:E=(6.626 x 10^-34 Js)(3.00 x 10^8 m/s) / (7.00 x 10^-7 m) = 2.84 x 10^-19 JViolet has higher energy but a smaller wavelength, they are inversely proportionalThe atomic spectra is more evidence for the particle nature of light.Rydberg EquationAllow us to predict position (wavelength) of line in H atom1/λ = R[(1/n1^2)-(1/n2^2)]Λ = wavelength of observed lightR= Rydberg constant (not a gas constant) (1.096776 x 10^7 m^-1)n= different shells in the atom (integers)n2>n1Use Rydberg Equation to find λ in nm of the photo emitted when a H atom undergoes a transition from n=5 to n=21/λ= (1.096776 x 10^7 m^-1)(1/4-1/25) = 1/λ = 2303229.6 m^-11/2303229.6m = λ = 434 nmAtomic Modele- spirals towards p+, the atom would collapseBohr’s Modele- only allowed in certain modelsquantized (fixed number)Bohr’s Model of the Hydrogen Atom1) Stationary States (fixed levels)2) E- don’t emit energy in stationary state3) E- can change stationary state by absorbing or emitting energy( light)E(photon) = ∆E(atom) = E(final) – E(initial) = h x VN= quantum number (describes what stationary state you’re in)Ground state = lowest energy level (stationary state), for H, e- in n=1Excited state = e- in orbit further from nucleus, for H e- in n>1Bohr’s model works for any 1 e- species:H (z=1)He+ (z=2)Li2+
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