Exam 2 fall 2004 ANSWERS

Exam 2 fall 2004 ANSWERS - State clearly your conclusion....

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Chem 105 Exam II Fall 2004 Name: _____________________________________ 1) Explain, in terms of the properties of photons (wavelength, frequency and/or energy – you decide which is the most important in this context), why it is acceptable to be exposed to low-medium intensity UV light for 15 minutes for tanning purposes but you must wear protection when exposed to very low intensity x-rays for even a second. (5 pts) The frequency of x-rays is higher (λ lower) and thus each photon has higher energy and can do significant damage. 2) Give a CONDENSED for Astatine and determine the number of valence electrons. (5 pts) [Xe] 6s 2 4f 14 5d 10 6p 5 7 valence electrons 3) Give a full electron configuration for the alkaline earth metal in the fifth row of the periodic table. (5 pts) 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 4) Use a box-type diagram to determine if Rhodium is diamagnetic or paramagnetic.
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Unformatted text preview: State clearly your conclusion. (7 pts) Rh is a d 7 transition metal: Unpaired electrons so paramagnetic 5) Give a CONDENSED electron configuration for a Nickel (II) ion (5 pts) [Ar]3d 8 1 2 3 12) Provide a correct Lewis Structure for nitric acid, include all resonance structures and a sketch of the resonance hybrid. (10 pts) 13) Calculate the average wavelength of a He atom in a sample of He gas at 0.005 atm and 100.0 K. In other words, what is the wavelength of the average He atom in the sample? (10 pts) v rms = sqrt(3RT/M) = sqrt(3*8.314*100/0.004) = 789.7 m/s Convert molar mass to mass of one He Atom Mass = Molar mass/N A = 0.004/6.02x10 23 = 6.64x10-27 = h/(mv) = 6.626x10-34 /(6.64x10-27 * 789.7) = 1.2x10-10 meters 4...
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Exam 2 fall 2004 ANSWERS - State clearly your conclusion....

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