Exam3 Formbwithanswers

CHM2045: Fall 2000—Exam #3

Form B

November 4, 2009

Instructions: BEFORE YOU BEGIN, MARK YOUR NAME, USF ID NUMBER, SECTION NUMBER, AND FORM LETTER ON YOUR SCANTRON SHEET. FAILURE TO DO THIS WILL RESULT IN A PENALTY. For each problem determine the best answer and mark the appropriate place on your scantron sheet. The exam consists of 20 questions and you will be given 50 minutes. Abbreviations and Symbols amount of substance n kelvin atmosphere atm kilo- (prefix) atomic mass unit u liter Avogadro constant NA milli- (prefix) Celsius temperature °C molar centi- (prefix) c molar mass enthalpy H mole ! frequency Planck’s constant gas constant R second gram g speed of light hour h wavelength joule J

Constants and Equations 23 -1 NA = 6.022 x 10 mol -1 -1 R = 8.3145 J mol K -1 -1 R = 0.08206 L-atm mol K E = h! c ="!

K k L m M M mol h s c "

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h = 6.626 x 10 J s 8 -1 c = 2.998 x 10 m s 1 L-atm = 101.325 J

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1 H 1.008

2 He 4.003

2

3 4 Li Be 6.941 9.012

5 6 7 8 9 10 B C N O F Ne 10.81 12.01 14.01 16.00 19.00 20.18

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11 12 Na Mg 22.99 24.31

13 14 15 16 17 18 Al Si P S Cl Ar 26.98 28.09 30.97 32.07 35.45 39.95

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19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr 39.10 40.08 44.96 47.88 50.94 52.00 54.94 55.85 58.93 58.69 63.55 65.39 69.72 72.61 74.92 78.96 79.90 83.80

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37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe 85.47 87.62 88.91 91.22 92.91 95.94 (98) 101.1 102.9 106.4 107.9 112.4 114.8 118.7 121.8 127.6 126.9 131.3

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55 56 57* 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn 132.9 137.3 138.9 178.5 180.9 183.9 186.2 190.2 192.2 195.1 197.0 200.6 204.4 207.2 209.0 (209) (210) (222)

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87 88 89** 104 105 106 107 108 109 110 111 112 Fr Ra Ac Rf Db Sg Bh Hs Mt (223) 226.0 227.0 (261) (262) (263) (262) (265) (266) (269) (272) (277)

Periodic Table

!

!

*Lanthanides

58 Ce 140.1

59 Pr 140.9

60 Nd 144.2

61 Pm (145)

62 Sm 150.4

63 Eu 152.0

64 Gd 157.3

65 Tb 158.9

66 Dy 162.5

67 Ho 164.9

68 Er 167.3

69 Tm 168.9

70 Yb 173.0

71 Lu 175.0

**Actinides

90 Th 232.0

91 Pa 231.0

92 U 238.0

93 Np 237.0

94 Pu (244)

95 Am (243)

96 Cm (247)

97 Bk (247)

98 Cf (251)

99 Es (252)

100 Fm (257)

101 Md (258)

102 No (259)

103 Lr (260)

FORM B

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CHM2045: Fall 2000—Exam #3

Form B

November 4, 2009

1. The following species all have the same number of electrons (we call this “isoelectronic”). Which would be expected to have the largest atomic radius? (A) O2(B) F (C) Na+ (D) N3(E) Mg2+ 2. Before Mendeleev, elements were listed in the order of their atomic weights (molar masses). When he set up the periodic table he deviated from this rule by listing Te (127.60 g/mol) before I (126.90 g/mol). What was the reason for this? (A) Iodine resembles F, Cl, and Br in its chemical properties; Te is much more like S and Se. (B) Ga and Ge had not yet been discovered; their absences misaligned the columns. (C) Mendeleev showed that the atomic weights of I and Te were incorrect. (D) Iodine is a solid whereas fluorine and chlorine are gases and bromine is a liquid. (E) Iodine is a metal whereas tellurium is a nonmetal. 3. The length of an H-H bond is 74 pm and that of an I-I bond is 266 pm. What is the most reasonable estimate for the length of an H-I bond? (A) 340 pm (B) 170 pm (C) 192 pm (D) 148 pm (E) 158 pm 4. Consider the following sets of quantum numbers, n, l, ml, and ms, respectively. Which of these, if any, is not allowed for an electron in an atom? (A) n = 1 l = 0 ml = 0 ms = +1/2 (B) n = 8 l = 7 ml = -6 ms = -1/2 (C) n = 3 l = 3 ml = -2 ms = +1/2 (D) n = 2 l = 1 ml = -1 ms = -1/2 (E) All the above are allowed. 5. For a hydrogen atom, which pair of energies (listed according to their n values) would have the greatest difference in energy? (A) n = 3 and n = 4 (B) n = 5 and n = 10 (C) n = 3 and n = 100 (D) n = 1 and n = 2 (E) Cannot be determined.

FORM B

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CHM2045: Fall 2000—Exam #3

Form B

November 4, 2009

6. Which is NOT directly determined by the principal quantum number, n, of the electron in a hydrogen atom? (A) The energy of the electron. (B) The minimum wavelength of the light needed to remove the electron from the atom. (C) The size of the corresponding atomic orbital(s). (D) The shape of the corresponding atomic orbital(s). (E) All of the above are directly determined by n. 7. What period 3 element is described by the following ionization energies (all in kJ/mol)? IE1 = 1012 IE2 = 1900 IE3 = 2910 IE4 = 4960 IE5 =6270 IE6 =22,200 (A) Mg (B) Si (C) P (D) S (E) Cl 8. How many inner shell (core) electrons do the following elements have, respectively? Hydrogen, Helium, Lithium, and Beryllium (A) 1, 1, 1, 1 (B) 0, 0, 1, 1 (C) 0, 0, 2, 1 (D) 0, 0, 2, 2 (E) 2, 2, 2, 2 9. Consider the following first ionization energy orderings. i) Al < Si < P < Cl ii) Be < Mg < Ca < Sr iii) I < Br < Cl < F iv) Na+ < Mg2+
FORM B

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CHM2045: Fall 2000—Exam #3

Form B

November 4, 2009

11. Which statement is TRUE? (A) We can sometimes know the exact location and speed of an electron at the same time. (B) All orbitals in a given atom are roughly the same size. (C) All orbitals in a given atom are roughly the same shape. (D) Since electrons have mass, we must always consider them to have particle properties and never wavelike properties. (E) Atoms are roughly spherical because when all of the different shaped orbitals are overlapped, they take on a roughly spherical shape. 12. The faster an electron is moving, the ________ its kinetic energy, and the __________ its wavelength. (A) higher, shorter (B) higher, longer (C) lower, longer (D) lower, shorter (E) More than one of the answer choices will result in a true statement. 13. Elements in the same family exhibit similar chemical properties because: (A) their atomic masses increase proportionally. (B) they exhibit identical core electron configurations. (C) they exhibit identical valence electron configurations. (D) they are in the same periodic table block and exhibit identical core electron configurations. (E) they are in the same periodic table block and exhibit similar valence electron configurations. 14. Give the ground state electron configuration for Sr. (A) [Kr]5s24d2 (B) [Kr]5s24d105p2 (C) [Kr]5s2 (D) [Kr]5s25d105p2 (E) [Kr]5s24d10 15. Calculate the wavelength of the red light emitted by a neon sign with a frequency of 4.74 ! 1014 Hz. (A) 633 nm (B) 158 nm (C) 142 nm (D) 704 nm (E) 466 nm 16. Which statement is TRUE? (A) A covalent bond is formed through the sharing of electrons. (B) A covalent bond has a lower potential energy than the two separate atoms. (C) An ionic bond is much stronger than most covalent bonds. (D) In metallic bonding all of the atoms pool their valence electrons. (E) All of the above statements are true.

FORM B

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CHM2045: Fall 2000—Exam #3

Form B

November 4, 2009

17. Give the ground state electron configuration for Br–. (A) [Ar]4s23d104p5 (B) [Ar]4s24p6 (C) [Ar]4s24d104p6 (D) [Ar]4s23d104p4 (E) [Ar]4s23d104p6 18. Which reaction below represents the second electron affinity of S? (A) S(g) + e– " S–(g) (B) S–(g) + e– " S2–(g) (C) S(g) " S(g) + e– (D) S–(g) " S(g) + e– (E) S2–(g) " S–(g) + e– 19. How many photons are contained in a burst of yellow light (589 nm) from a sodium lamp that contains 609 kJ of energy? (A) 3.37 ! 1019 photons (B) 3.06 ! 1030 photons (C) 1.81 ! 1024 photons (D) 4.03 ! 1028 photons (E) 2.48 ! 1025 photons 20. Which energy gap in the Bohr Model would be associated with the longest wavelength? (A) from n = 2 to n = 1 (B) from n = 6 to n = 5 (C) from n = 10 to n = 9 (D) from n = 11 to n = 10 (E) They have the same wavelength. 21. Choose the orbital diagram that represents the ground state of N. (A) (B) (C) (D) (E)

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CHM2045: Fall 2000—Exam #3

Form B

November 4, 2009

22. Which is a FALSE statement? (A) The lattice energy of LiCl has a larger magnitude than that of NaCl. (B) The lattice energy of CaO has a larger magnitude than that of NaCl. (C) Na reacts with # Cl2 to form NaCl molecules. (D) Some ionic compounds may not conduct electricity when dissolved in water. (E) Lattice energy decreases as ionic radius increases as long as charge remains constant. 23. In the Born-Haber cycle for Mg(s) + Cl2(g) " MgCl2(s), which step(s) is (are) exothermic for the formation of crystalline solid? (The following may not be balanced equations, but describe reaction processes.) (1) Mg(g) + 2Cl (g) ! Mg2+(g) + 2Cl (g) (2) Mg2+(g) + 2Cl(g) ! Mg2+(g) + 2Cl– (g) (3) Mg(s) + Cl2(g) ! Mg(g) + Cl2(g) (4) Mg(g) + Cl2 (g) ! Mg(g) + 2Cl (g) (5) Mg2+(g) + 2Cl– (g) ! MgCl2(g) (A) (1) and (3) (B) (1), (3), and (4) (C) (5) (D) (2) and (5) (E) (1), (2), and (5) 24. Which of the following concepts/models/phenomena are related to “quantized energy levels”? (A) Fireworks (B) Neils Bohr’s model for the atom (C) the “line spectra” of helium emission (D) Both (b) and (c) (E) All of the above. 25. Which one does not have a completely full quantum level? (A) Na+ (B) O2 (C) O2– (D) He (E) The quantum levels are completely full in all of the above.

FORM B

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