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HW02 Quy

# HW02 Quy - perlick(app582 HW02 quy(50970 This print-out...

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perlick (app582) – HW02 – quy – (50970) 1 This print-out should have 34 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering. 001(part1of3)10.0points What is the principal quantum number for the orbital 3 d ? 1. 5 2. 2 3. None of these 4. 6 5. 4 6. 3 correct Explanation: n = 3 002(part2of3)10.0points What is the orbital angular momentum quan- tum number for the orbital 3 d ? 1. 3 2. 1 3. 0 4. 2 correct 5. 4 6. None of these Explanation: = 2 003(part3of3)10.0points How many magnetic quantum numbers does the orbital 3 d have? 1. 5 correct 2. 7 3. None of these 4. 3 5. 9 6. 1 Explanation: m = - 2 , - 1 , 0 , 1 , 2 004 10.0points How many total nodal planes are present in the complete set of 3 d orbitals? 1. 10 2. 3 3. 16 4. 20 5. 8 correct 6. 5 Explanation: There are 5 orbitals in the 3 d set. 4 of those orbitals are cloverleaf-shaped and have 2 nodal planes each. That combines to give 8 total nodal planes for the set. The other (5th) orbital is the d z 2 orbital which has 2 nodal cones, not planes. 005 10.0points How many nodes are present in a 3 s and a 3 p orbital, respectively? 1. 2 and 1 2. 2 and 2 correct 3. 1 and 1 4. 0 and 2 5. 0 and 1

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perlick (app582) – HW02 – quy – (50970) 2 Explanation: A node is a point, a plane or a three dimen- sional region of space where the sign of the wavefunction changes from positive to nega- tive, (or negative to positive) so it equals zero. The lowest energy s orbital is 1 s , and this has no nodes – the wavefunction is always posi- tive. As we go to the next higher value of n we add a spherical node, so 2 s would have one node, and 3 s two. The lowest energy p or- bital is 2 p ; it has one nodal plane which cuts through the nucleus (the two ’lobes’ have op- posite signs). Again, as we go to the next higher value of n we add a spherical node, so a 3 p orbital has two nodes. 006 10.0points The transition metals are elements with par- tially filled 1. f subshells. 2. p subshells. 3. d subshells. correct 4. s subshells. Explanation: In transition metals, d orbitals are being filled. 007 10.0points An element with 20 protons and 20 electrons gains one electron. The electron goes into what type of orbital? 1. 3 p 2. 3 s 3. 4 s 4. 4 d 5. 4 p 6. 3 d correct Explanation: This element has electron configuration [Ar] 4 s 2 . The next electron goes into the 3 d orbital according to the Aufbau principle. 008 10.0points Which element is predicted to have the ground-state electron configuration [Xe] 4 f 14 5 d 5 6 s 2 ? 1. irdium 2. cesium 3. hafnium 4. lutetium 5. tungsten 6. tantalum 7. barium 8. xenon 9. rhenium correct 10. osmium Explanation: Remembering the noble gas shorthand, count all of the superscripts that appear in the electron configuration. This will give the number of electrons which in a neutral atom is equal to the number of protons (atomic number of the element). Note some excep- tions do occur in the electron configuration of atoms because of the stability of either a full or half-full outermost d -orbital; sometimes an electron is ‘shuffled’ from the ( n - 1) s orbital.
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