2. Atoms with very similar electronegativity values are expected to form

Transcription

1 AP hemistry Practice Test #6 hapter 8 and 9 1. Which of the following statements is incorrect? a. Ionic bonding results from the transfer of electrons from one atom to another. b. Dipole moments result from the unequal distribution of electrons in a molecule. c. The electrons in a polar bond are found nearer to the more electronegative element. d. A molecule with very polar bonds can be nonpolar. e. Linear molecules cannot have a net dipole moment. 2. Atoms with very similar electronegativity values are expected to form a. no bonds. b. covalent bonds. c. triple bonds. d. ionic bonds. e. none of these 3. For the elements Rb, F, and, the order of increasing electronegativity is: a. Rb < F < b. Rb < < F c. < F < Rb d. F < Rb < e. None of these 4. In which case is the bond polarity incorrect? a. δ+ -F δ- b. δ+ K- δ- c. δ+ Mg-δd. δ+ l-i δ- e. δ+ Si-S δ- 5. The electron pair in a -F bond could be considered a. closer to because carbon has a larger radius and thus exerts greater control over the shared electron pair. b. closer to F because fluorine has a higher electronegativity value than carbon. c. closer to because carbon has a lower electronegativity value than fluorine. d. an inadequate model since the bond is ionic. e. centrally located directly between the and F. 6. What is the correct order of the following bonds in terms of decreasing polarity? a. N-l, P-l, As-l b. P-l, N-l, As-l c. As-l, N-l, P-l d. P-l, As-l, N-l e. As-l, P-l, N-l

2 7. ow many of the following molecules possess dipole moments? B 3, 4, Pl 5, 2, 2 a. 1 b. 2 c. 3 d. 4 e Which of the following molecules (or ions) has a dipole moment? a. 2 b c. N 4 + d. PF 3 e. two of them do 9. hoose the statement that best describes the Pbl 4 molecule in the gas phase. a. The bond angles are all about 109 o. b. The molecule is polar. c. The molecule has a dipole moment. d. The bonds are nonpolar. e. a, b, and c 10. When electrons in a molecule are not found between a pair of atoms but move throughout the molecule, this is called a. ionic bonding. b. covalent bonding. c. polar covalent bonding. d. delocalization of the electrons. e. a dipole moment. 11. hoose the molecule with the strongest bond. a. F b. l c. Br d. I e. All are equal. 12. As the number of bonds between two carbon atoms increases, which one of the following decreases? a. number of electrons between the carbon atoms b. bond energy c. bond length d. all of these e. none of these

3 13. Using the following bond energies Bond Bond Energy (kj/mol) = 495 = estimate the heat of combustion for one mole of acetylene: 2 2 (g) + (5/2) 2 (g) 2 2 (g) + 2 (g) a kj b kj c kj d kj e kj 14. Which of the following species is best described by drawing resonance structures? a. P 3 b. N 4 + c. 3 d. S 3 - e. N Use the following to answer questions 15-17: Using the following electronegativity values N select from the following group the molecule that fits the given statement: a) 3 b)_ 2 c) 3 l d) 2 6 e) none 15. This molecule contains a carbon atom with trigonal planar geometry. (a) 16. This molecule is the most polar. (a) 17. This molecule shows the smallest number of lone pairs in its Lewis structure. (d)

4 18. As indicated by Lewis structures, which of the following would probably not exist as a stable molecule? a. 3 b. 2 c. 3 d. 2 2 e Select the best Lewis structure for acetone, 3 3. (b) a. b. c. d. e.

5 20. Which of the following is the correct order for molecules from most to least polar? a. 4 > F 2 l 2 > F 2 2 > l 4 > l 2 2 b. 4 > F 2 2 > F 2 l 2 > l 4 > l 2 2 c. F 2 l 2 > F 2 2 > l 2 2 > 4 = l 4 d. F 2 2 > l 2 2 > F 2 l 2 > 4 = l 4 e. F 2 l 2 > F 2 2 > l 4 > l 2 2 > f the following, which molecule has the largest bond angle? a. 3 b. F 2 c. N d. 2 e. More than one of the above have equally large bond angles. 22. According to the VSEPR model, the arrangement of electron pairs around N 3 and 4 are a. different because in each case there are a different number of atoms around the central atom. b. different because in each case there are a different number of electron pairs around the central atom. c. the same because both nitrogen and carbon are both in the second period. d. the same because in each case there are the same number of electron pairs around the central atom. e. different or the same, depending on the conditions leading to maximum repulsion. 23. Which of the following atoms cannot exceed the octet rule in a molecule? a. N b. S c. P d. I e. All of the atoms (a-d) can exceed the octet rule. 24. In the cyanide ion (N - ), the nitrogen has a formal charge of a. -2 b. -1 c. 0 d. 2 e ow many of the following molecules SF 2, SF 4, SF 6, Si 2 - are polar? a. 0 b. 1 c. 2 d. 3 e. 4

6 26. ow many resonance structures can be drawn for the molecule 3? a. 1 b. 2 c. 3 d. 4 e hoose the electron dot formula that most accurately describes the bonding in S 2. (int: onsider formal charges.) a) b) c) d) e) S S S S S S S S S S 28. In the Lewis structure for elemental nitrogen there is (are) a. a single bond between the nitrogens. b. a double bond between the nitrogens. c. a triple bond between the nitrogens. d. three unpaired electrons. e. none of the above Use the following to answer questions 29-31: onsider the compound crotonaldehyde, whose skeleton is ow many electrons must be shown in the Lewis structure of this molecule? a. 12 b. 18 c. 24 d. 28 e. 32

7 30. ow many nonbonding electrons appear in the Lewis structure of this molecule? a. 2 b. 4 c. 6 d. 8 e Which carbon in this molecule has tetrahedral bonding? a. 1 b. 2 c. 3 d. 4 e. all 32. The Lewis structure for 3 B 3 is a) b) c) d) B B B B e) B

8 Use the following to answer questions 33-34: onsider the following molecules. I. BF 3 II. Br 3 ( is the central atom) III. Br 2 IV. Xel 2 V. VI. SF 4 Select the molecule(s) that fit the given statement. 33. These molecules violate the octet rule. a. I, II, IV b. I, III, IV, VI c. III, V, VI d. I, IV, VI e. I, II, IV, VI 34. These molecules have a zero net dipole moment. a. III, V b. I, III, IV c. II, IV, V d. I, III, IV, VI e. none of them 35. The geometry of Asl 5 is a. trigonal bipyramidal b. square pyramidal c. distorted tetrahedral d. octahedral e. none of these 36. ow many of the following molecules or ions are linear? N 3 N 4 + N 2 N 2 a. 0 b. 1 c. 2 d. 3 e. 4

9 37. The bond angles about the carbon atoms in the formaldehyde molecule, 2 =, are about: a. 120 o b. 60 o c. 109 o d. 180 o e. 90 o 38. Which of the following species has a trigonal bypyramid structure? a. N 3 b. IF 5 c. I 3 - d. Pl 5 e. none of these 39. Which ion is planar? a. N 4 + b c. S 3 2- d. l 3 - e. all are planar 40. In the molecule XeF 2, how many pairs of electrons surround Xe and what is the molecular geometry? a. 4, bent b. 4, pyramidal c. 5, linear d. 5, bent e. 6, linear 41. ow many of the following molecules have all of their atoms in the same plane> 2 = 2 F 2 2 N 3 2 Bel 2 a. 3 b. 4 c. 5 d. 6 e. 7 Use the following to answer questions 42-45: For each of the following compounds: a) draw the Lewis structure b) give the shape of the molecule c) indicate the polarity of the molecule 42. AlF 3 trigonal planar, nonpolar

10 43. N 3 trigonal pyramidal; polar 44. Il 4 - square planar; nonpolar 45. BrI 3 tetrahedral; polar 46. If a compound has a number of individual dipoles, then I. it is polar overall II. there is an electronegativity difference between the bonded atoms III. it is ionic IV. it doesn t have resonance a. II only b. II, IV c. I, II, IV d. I, III e. All of the above statements are correct. 47. The hybridization of the phosphorus atom in the cation P 2 + is: a. sp 2 b. sp 3 c. dsp d. sp e. none of these 48. Which of the following statements is (are) incorrect? I. The hybridization of boron in BF 3 is sp 2. II. The molecule XeF 4 is nonpolar. III. The bond order of N 2 is three. IV. The molecule N has two pi bonds and two sigma bonds. a. All four statements are correct. b. II is incorrect. c. I and IV are incorrect. d. II and III are incorrect. e. II, III, and IV are incorrect. 49. The hybridization of the central atom in I 3 - is: a. sp b. sp 2 c. sp 3 d. dsp 3 e. d 2 sp 3

11 50. Which of the following does not contain at least one pi bond? a. 2 b. 2 c. 2 4 d. 3 8 e. All of the aboe (a-d) contain at least one pi bond. 51. onsider the following Lewis structure Which statement about the molecule is false? a. There are 10 sigma and 2 pi bonds. b. -2 is sp 2 hybridized with bond angles of 120 o. c. xygen is sp 3 hybridized. d. This molecule contains 28 valence electrons. e. There are some -- bond angles of about 109 o in the molecule. 52. onsider the following Lewis structure: N a. sp 3 sp 3 sp sp 2 b. sp sp 3 sp sp c. sp sp 2 sp sp 2 d. sp 2 sp 3 sp 2 sp 3 e. sp sp 3 sp 2 sp 53. The hybridization of Br in BrF 3 is a. sp b. sp 2 c. sp 3 d. dsp 3 e. d 2 sp 3

12 54. The hybridization of the central atom Al, in AlBr 3 is a. sp b. sp 2 c. sp 3 d. dsp 3 e. d 2 sp 3 Use the following to answer questions 55-57: Tetracyanoethylene has the skeleton shown below: From its Lewis structure determine the following: 55. ow many sigma and pi bonds are in the molecule? a. 5 sigma and 9 pi b. 6 sigma and 8 pi c. 9 sigma and 7 pi d. 9 sigma and 9 pi e. 5 sigma and 8 pi 56. ow many of the atoms are sp 2 hybridized? a. 2 b. 4 c. 6 d. 8 e ow many of the atoms of sp hybridized? a. 2 b. 4 c. 6 d. 8 e. 10