Download Spring 2006 Exam 1 Review: Electromagnetic Radiation & Quantum Mechanics and more Study notes Chemistry in PDF only on Docsity! McCord Exam 1 Review Sheet Spring 2006 Which Chapter/Sections are covered? All of Chapter 1 – that’s it. All material covered on homeworks 1-3. Concentrate on the subject matter I emphasized in class and on the homeworks. Come in mentally prepared to answer at least 20 questions, maybe more. Yes, there will be calculations, but most of the exam will be theory and concepts. You need to understand the theory and concepts – getting a homework question right does not necessarily mean you really understand the material. Energy traveling at the speed of light Know what electromagnetic radiation is and how we depict it on the page and conceptually. Know the basics of the entire electromagnetic spectrum (see Figure 1.3, p. 3). Know the approximate wavelengths for each type of radiation given (LOOK at that figure). Know also, that visible light is in the 400- 700 nm range (that’s blue end to red end). Other than the two ends, I do not expect you to know the wavelengths of all the colors of the rainbow – however, you SHOULD know the ordering of the colors (think Roy G. Biv). Know the two basic equations that describe electromagnetic radiation: ! E = h" ! c = "# Know how to use this equations to calculate various wavelengths, frequencies, and energies of photons. Know the two views of electromagnetic radiation: as a wave and as a particle (photons) All moving particles have wavelength? Yes. Louis de Broglie said if light can be treated as a particle (photon) then why not the other way around? Any moving particle with mass and velocity should have a corresponding wavelength. ! " = h p = h mv where p is momentum (p = mv) The most important moving object for us is the electron. Now we can treat the electron as a wave. When confined to the region around the nucleus, the electron behaves as a standing wave. What is the essence (observations) of the photoelectric effect? (p. 6) How did Einstein explain this effect? How does this relate to the work function (Φ) of a metal: ! 1 2 mv 2 = h" #$ Be able to calculate any part of this equation (m, v, Φ, or ν) if given any 3 of the 4 variables in it That thing is RED-hot! What are the characteristics of black-body radiation? See Figure 1.4, p. 4 for a good idea. Note the range of wavelengths for a black-body radiator. They depend on the temperature. How does the spectrum shift with temperature? Where is the maximum intensity of radiation? Use Wein’s law for that one: ! T" max = 1 5 c 2 where c2 is the second radiation constant. Realize the stark contrast in spectra between black-body radiation and . . . The Emission Spectrum of Hydrogen Check out those lines. Lines I tell you. Not broad bands of continuous wavelengths but very very narrow precise lines. It’s like hydrogen is speaking to us. What is it saying? It is saying, “I have quantized energy levels!” “When I’m excited, I spit out very specific quanta of energy.” Who listened? Several smart guys but lets chalk one up for Bohr for realizing that the photon that is emitted is due to the energy difference in quantum levels within the atom. As an electron falls from an excited state to a lower energy state, a photon is emitted that corresponds to the energy gap. Other’s put some real math on the energies (Balmer) but Rydberg came up with a very insightful equation: ! " = R 1 n 1 2 # 1 n 2 2 $ % & ' ( ) n1 = 1, 2, . . . n2 = n1+1, n1+2, … You can use this equation to calculate all kinds of energy transitions. You need to know the fundamental difference in the Balmer series and the Lyman series (p. 18). But WHERE exactly IS the electron? What is the Heisenberg uncertainty principle? Yes, the equation is ! "p"x # 1 2 h , but what does this really mean? Can we precisely know the momentum AND position of the electron in the atom?
