Chem 120A-Fall 2005-Midterm 2

Chem 120A-Fall 2005-Midterm 2 - Chemistry 120A Professors...

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Chemistry 120A Name: Professors H. Yang & W. Lester Jr. Exam #2 Nov. 4, 2005 1 Examination #2 Key Chemistry 120A Fall Semester 2005 This test is worth a total of 100 points with each problem having the value given below. The exam is 12 pages long including this cover sheet, 8 pages of problems, 2 blank pages, and 1 page of equations. Please present your work in a tidy and systematic manner to facilitate partial credit where appropriate. This exam is not designed to be full of trick questions, please just fill out the most straight forward answer that you can come up with in a concise form. You have until 11 a.m. to finish this examination Question 1 20 points 20 _ Question 2 20 points 20 _ Question 3 20 points 20 _ Question 4 20 points 20 _ Question 5 20 points 20 _ Total 100 points 100 _
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Chemistry 120A Name: Professors H. Yang & W. Lester Jr. Exam #2 Nov. 4, 2005 2 1) This problem is intended to test your knowledge of basic of quantum mechanics concepts. Answer these questions with how often you think the statement is always true, sometimes true, or never true. (20 points total) a. In the hydrogen atom, the values of the three components ( x , y , and z ) of angular momentum can be measured simultaneously. (4 points) Never b. The 2 s and 2 p states are degenerate. (4 points) Sometimes c. In variational theory, the calculated energy is less than the true ground state energy. (4 points) Never d. In first-order perturbation theory, the correction to the unperturbed energy will be negative ( i.e. , the perturbed energy will be lower than the unperturbed energy). (4 points) Sometimes e. If the states have the same value of L and S , then for a subshell that is less than half filled, the state with the smallest value of J is the most stable. (4 points) Always
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Chemistry 120A Name: Professors H. Yang & W. Lester Jr. Exam #2 Nov. 4, 2005 3 2) Provide a short answer to each of the following questions. (20 points total) a. Why is the energy obtained from the Hartree-Fock SCF method different from the sum of the orbital energies? (4 points) We double count the 2 electron portion of the orbital energy if we sum the orbital energies, i.e. we double count J and K.
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This note was uploaded on 09/20/2011 for the course CHEMISTRY 120 taught by Professor Head-gordon during the Spring '11 term at ASU.

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Chem 120A-Fall 2005-Midterm 2 - Chemistry 120A Professors...

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