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CHEM 31 SI Wednesday November 4 Quantum Numbers and Electron Configurations Worksheet (review) (#70 from text) An electron in a hydrogen atom relaxes to the n = 4 level, emitting light of 114 THz. What is the value of n for the level in which the electron originated? (Tera = 1012) Answer: n = 6 (# 78 from text) The energy required to ionize sodium is 496 kJ / mol. What minimum frequency of light is required to ionize sodium? Answer = 1.24 x 1015 Hz c=λ ∙ ν c = 2.99792458 x 108 meters/second h = 6.626 x 10-34 Joules ∙ Second = Planck’ hc ∆Eatom = E emitted (or absorbed) radiation = hν = Ephoton = /λ ∆E = Efinal – Einitial = hv = hc/λ = -2.18 x 10-18 J φ = energy of a photon when threshold is achieved hv = φ CHEM 31 SI Wednesday November 4 What are the possible values of n, l, ml, and ms? What does each of these determine? 19. List all of the possible values of l (angular momentum), ml (magnetic), and ms (spin) quantum numbers for the following values of n (the principal quantum number): B) n = 2 D) n = 4 20. Based on the above question, the total number of electrons possible for a given n-value is equal to: A. 2n B. 2n2 C. 2 (n-1) D. 2(2n + 1) 18. Which of the following accurately describes l (the angular momentum quantum number)? A. The value of l can be both positive and negative B. The value of l specifies the orientation of the orbital C. The value of l specifies the energy level of the orbital. D. The number of possible l values equals the value of n. CHEM 31 SI Wednesday November 4 21. Supply the missing quantum numbers and sublevel names: n l ml Name __ __ 0 4p 2 1 0 __ 3 2 -2 __ __ __ __ 2s Are the following sets of quantum numbers allowed (Yes or No)? If not, change the value of only one of the quantum numbers to make the set allowed. Allowed? Changed Quantum Number if No: n = 3, l = 0, ml = 0, ms = 1 Y/N ____________________________ n = 1, l = 1, ml = 0, ms = 1/2 Y/N ____________________________ n = 8, l = 7, ml = -6, ms = -1/2 Y/N ____________________________ n = 2, l = -1, ml = 1, ms = 1/2 Y/N ____________________________ What is the maximum number of electrons in an atom that can have these quantum numbers? n = 2, l = 0, ml = 0 _______________ n = 3, l = 1, ms = ½ _______________ n = 5, ml = 1 _______________ n=4 _______________ CHEM 31 SI Wednesday November 4 Write out the mnemonic for remembering the order to assigning electron configurations to elements in their ground state orbitals: What two transition metals do we need to know that are exceptions to the rules when writing ground state electron configurations? Write the Ground State Electron Configuration and orbital diagram for the following atoms, using the noble gas abbreviation: N Cu Nd Sr I Use a phrase to describe why the 2s orbital is more stable (lower energy) versus 2p. Explain briefly why the atomic radii increase moving down the periodic table, and decrease moving to the right on the periodic table.