# Exam 1 - Version 239 Exam 1 McCord(53745 This print-out...

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Version 239 – Exam 1 – McCord – (53745) 1 This print-out should have 27 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering. McCord 1pm c = 3 . 00 × 10 8 m/s h = 6 . 626 × 10 - 34 J · s m e = 9 . 11 × 10 - 31 kg N A = 6 . 022 × 10 23 mol - 1 ν = R parenleftbigg 1 n 2 1 - 1 n 2 2 parenrightbigg where R = 3 . 29 × 10 15 s - 1 ψ n ( x ) = parenleftbigg 2 L parenrightbigg 1 2 sin parenleftBig nπx L parenrightBig E n = n 2 h 2 8 mL 2 n = 1 , 2 , 3 , · · · 001 10.0 points In general, atomic size tends to increase 1. from top to bottom and from left to right on the periodic table. 2. from bottom to top and from right to left on the periodic table. 3. There is no relationship between the size of an atom and its position on the periodic table. 4. from bottom to top and from left to right on the periodic table. 5. from top to bottom and from right to left on the periodic table. correct Explanation: Atomic sizes are largest in the bottom left- handcorner and smallest in the top right-hand corner of the periodic table. 002 10.0 points The electron in the n = 5 level of a hydrogen atom emits a photon with a wavelength of 1280 nm. To what energy level does the electron move? 1. 5 2. 9 3. 8 4. 4 5. 6 6. 2 7. 7 8. 3 correct 9. 1 Explanation: ν = c λ = 3 × 10 8 m / s 1280 × 10 - 9 m = 2 . 34375 × 10 14 s - 1 Applying Rydberg’s equation, ν = R parenleftbigg 1 n 2 1 - 1 n 2 2 parenrightbigg ν R = 1 n 2 1 - 1 n 2 2 1 n 2 1 = ν R + 1 n 2 2 = 2 . 344 × 10 14 Hz 3 . 29 × 10 15 Hz + 1 5 2 = 0 . 111 n 1 = 3 003 10.0 points In a one-dimensional particle in a box, for n = 6, how many wavelengths equals the size of the box? 1. 1

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Version 239 – Exam 1 – McCord – (53745) 2 2. 2.5 3. 12 4. 3 correct 5. 6 Explanation: For n = 6 the wavefunction would be x = 0 x = L 004 10.0 points Electron affinity corresponds to the energy released or absorbed in which process (for atom A)? 1. A A + + 2 e - 2. A + e - A - correct 3. None of these 4. A 50 electron volt electron collides with A to give A + + 2 e - . 5. A A + + e - Explanation: Electron affinity is defined as the amount of energy absorbed in the process in which an electron is added to a neutral isolated gaseous atom to form a gaseous ion with a - 1 charge. This is represented by the equation A + e - A - . 005 10.0 points What is a set of correct quantum numbers ( n , , m l ) for the last electron of P - ? 1. 3,1,1 correct 2. 2,0,1 3. 3,1,-2 4. 3,2,1 5. 2,0,0 6. 3,0,0 7. 2,1,1 8. 3,2,0 Explanation: The electron configuration of P - is [Ne] 3s 2 3p 4 . The principal quantum number ( n ) is 3. The angular momentum quantum number is 1 for the p orbital and m l can be 1, 0, -1. 006 10.0 points The graph shows the radial distribution plots for the 1s wavefunctions for H, He, and He + . A B C radius 4 πr 2 Ψ 2 Which plot is the 1s wavefunction for the He + ion?
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