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Term Test 2B Instructor: Dr. Robert Davis Chemistry 1050 Name: _____________________ Wednesday, November 2, 2011 ANSWER THE TEST QUESTIONS IN THE SPACE PROVIDED. MARKS WILL BE DEDUCTED FOR INCORRECT USE OF SIGNIFICANT FIGURES AND FOR LACK OF UNITS IN CALCULATIONS. Marking Scheme Question Value Mark Part A: Short Answer Questions A1 – A11 24 Part B: Longer Answer Questions B1 5 B2 3 B3 8 Total 40 % Grade Useful Equation: En = 1 −Z2 RH n2 Part A: Short Answer Questions [Value] [4] A1. Write condensed ground state electron configurations for the species listed using spdf notation. S ________________________________________________ Cu ________________________________________________ Ca2+ ________________________________________________ As3– ________________________________________________ [1] A2. Write formulas for two ions that are isoelectronic with Ar. [2] A3. Write a chemical equation corresponding to [3] A4. (a) the second ionization energy of potassium (b) the electron affinity of sulfur Determine the maximum number of electrons that can have the following combinations of quantum numbers. n = 2, l = 1 ________________________ n = 3, l = 2, ms = ½ ________________________ n = 4, ms = ½ [1] A5. Circle the chemical formulas for the two species that are diamagnetic Ba, [1] A6. A7. P, K, S2–, Te Give a possible set of quantum numbers for an electron in a 5f orbital n= [1] ________________________ , l = , ml = , ms = Draw a fully labelled orbital diagram for P. 2 [3] [3] [2] [2] A8. A9. Give definitions or brief explanations of the following: (a) Hund’s Rule (b) an anion is larger than the neutral atom from which it is formed (c) electron shielding Arrange the following in order of increasing size (a) Se, O, S, Te, He smallest ___ ___ ___ ___ ___ biggest (b) Si, N, Mg, F, Li (c) Kr, Br-, As3–, Sr2+, Al3+ smallest ___ ___ ___ ___ ___ biggest smallest ___ ___ ___ ___ ___ biggest A10. Identify the following (a) the smallest electrically neutral second period atom (b) the second period atom with the largest third ionization energy (c) an element that forms an acidic oxide A11. Determine the number of radial nodes and angular nodes for the following orbitals: (a) 1s (b) 3p 3 Part B: Longer Answer Questions [5] B1. The lone electron in a He+ ion makes a transition from n = 3 to n = 4. (a) Does this transition involve the absorption or emission of a photon? (b) Calculate the energy, frequency and wavelength of the photon. 4 [3] B2. The Cl2 molecule can be dissociated to produce two Cl atoms using light with a wavelength of 4.923 X 10–7 m. Determine the bond dissociation energy of Cl2 in kJ mol–1. 5 [8] B3. Give brief explanations for the following: (a) The third ionization energy of Mg is much larger than the third ionization energy of aluminum. (b) What is the difference between the radial probability density R2(r) and the radial probability distribution 4πr2 R2(r) for a particular orbital. (c) The atomic radius of F is smaller than the atomic radius of Li. (d) The first ionization energy of N is larger than the first ionization energy of As. 6