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Unformatted text preview: Chemistry 181H Fall, 2007 EXAM II Thursday, 8 Nov 2oo7 WRITE your Name Student Number Recitation Time: Monday There are 7 questions on this exam, worth 15 points each. Write your answer, showing all work to each on each page. A list of potentially useful equations is on pages 9 and 10. A periodic table is contained on page 11. # Score 1 /15 2 /15 3 /15 4 /15 5 /15 6 /15 7 /15 total /100 1 1. One of the most sensitive light detectors uses an alloy that has the very low work function of 2.40x10 19 J (1.5 eV), a value that is lower than that of any single element. (a) Calculate the value of the lowest frequency of light that will eject a photoelectron from this surface. (5 points) (b) Calculate the wavelength of the electrons that are emitted from the surface of this material that is irradiated with blue light at 460 nm. (10 points) 2 2. This problem concentrates on an electron trapped in a one dimen sional box with V(x)=0. The box has a length L=100 nm. (a) Does this system have any degenerate states? Indicate why or why not. (5 points) (b) What is the energy (in joules) of the photon that will be released when the electron drops from the first excited state to the ground state of this system? (5 points) (c) Estimate the probability that the electron can be found between x=0.2L and x=0.21L if it is in the first excited state of this system. (5 points) 3 3. Answer the following questions relating to atomic structure. (a) Give a clear and concise explanation for the following facts: The first ionization potentials of the elements in the pgroup of the top row of the periodic table increase with atomic number, except that the first ionization potential of a free oxygen atom is less than...
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 Fall '08
 MORRISSEY
 Atom, Hydrogen atom, ﬁrst excited state

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