Unit-3 Chemical Bonding Practice Exam

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1 Name: Class: _ Date: _ Unit-3 Chemical Bonding Practice Exam Multiple Choice - NO CALCULATORS, show your work and justify your answers. 1. The concentration of a red colored solution of cobalt ions needs to be determined. What spectroscopic technique would be the best choice? a. Photoelectron spectroscopy because the electron arrangement is responsible for the color b. UV-Vis spectroscopy because the solution has a color c. Infrared spectroscopy because the solution is red d. Mass spectrometry because knowing the mass allows for calculation of concentration Element Atomic Radius First Ionization Energy Calcium 194 pm 590 kj/mol Potassium 2. Based on periodic trends and the data in the table above, which of the following are the most probable values of the atomic radius and the first ionization energy for potassium, respectively? a. 242 pm, 633 kj/mol c. 120 pm, 633 kj/mol b. 242 pm, 419 kj/mol d. 120 pm, 419 kj/mol 3. Which of the following structures does not have a planar geometry? a. XeF 4 c. NO - 3 b. BF 3 d. SO 3 The next three questions refer to the following gaseous molecules. (A) BeCl2 (B) SO2 (C) N2 (D) O2 4. Is a polar molecule. a. A c. C b. B d. D 5. Is best represented by two or more resonance forms a. A c. C b. B d. D 6. What properites listed below are true of ionic compounds? I. Electrons are shared between bonding atoms II. High melting points III. High volatility IV. Malleable V. Brittle - breaking when ions of like charge aline. VI. Higher concentration in water results in lower electrical current. a. All listed are properites of ionic c. Only I., III, IV compounds b. Only II, V d. Only II, III, VI 1

2 Name: 7. Under which of the following conditions of temperature and pressure will H 2 gas be expected to behave most like an ideal gas? a. 50 K and 0.10 atm c. 500 K and 0.10 atm b. 50 K and 5.0 atm d. 500 K and 50 atm 8. Which of the following molecules has the largest dipole moment? a. CH 4 c. PF 5 b. PH 3 d. H 2 O 9. Which of the following structures have a linear geometry? I. XeF 2 II. IF - 2 III. CO 2 a. I only c. III only b. II only d. II and III 10. How many sigma and pi bonds are there in C 2 H 4? a. 1 sigma and 1 pi c. 4 sigma and 2 pi b. 4 sigma and 1 pi d. 5 sigma and 1 pi 11. Covalent bonds between two atoms are more polar when a. there is a large difference in c. electrons are transferred, not shared electronegativity b. electrons are shared equally d. electronegativities are the same 12. What are the formal charges on the N, C, S a. 0, 0, -1 c. 0, -1, 0 b. -1, 0, 0 d. 5, 4, Which bond has the highest bond order? a. single c. triple b. double d. ionic 14. C 2 H 2(g) + Cl 2(g) -> C 2 H 2 Cl 2(g) When the reaction above occurs, does the hybridization of the carbon atoms change? a. Yes; it changes from sp to sp2. b. Yes; it changes from sp to sp3. c. Yes; it changes from sp2 to sp3. d. No, it does not change. 15. N 2 molecules absorb ultraviolet light but not visible light. I 2 molecules absorb both visible and ultraviolet light. Which of the following statements explains the observations? a. More energy is required to make N 2 molecules vibrate than is required to make I 2 molecules vibrate. b. More energy is required to remove an electron from an I 2 molecule than is required to remove an electron from a N 2 molecule. c. Visible light does not produce transitions between electronic energy levels in the N 2 molecule but does produce transitions in the I 2 molecule. d. The molecular mass of I 2 is greater than the molecular mass of N 2. 2

3 Name: 16. Which of the following bonds has the longest bondlength? a. N - O c. N - Br b. N - F d. N - Cl 17. Which of the following is LEAST likely to exist? a. PCl 5 c. NF 3 b. PBr 3 d. NI Which compound has the highest melting point? a. NaF c. MgO b. Al 2 O 3 d. CaF Which of the following molecules is polar? a. CO 2 c. BF 3 b. CH 4 d. CH 3 F 20. Which bond below is least ionic? a. Ca - Cl c. N - O b. Al - F d. C - H 21. Which of the following molecules is nonpolar but has polar covalent bonds? a. N 2 c. H 2 O b. H 2 O 2 d. CCl Lewis electron-dot diagrams for CO 2 and SO 2 are given above. The molecular geometry and polarity of the two substances are a. the same because the molecular formulas are similar c. different because the lone pair of electrons on the S atom make it the b. the same because C and S have similar electronegativity values negative end of a dipole d. different because S has a greater number of electron domains (regions of electron density) surrounding it than C has 23. The central atom in a molecule displays sp 3 hybridization. What shape do the charge clouds make? a. Linear c. Tetrahedral b. Trigonal Planar d. Square pyramidal 24. Which of the following properties generally decreases across the periodic table from sodium to chlorine? a. First ionization energy c. Electronegativity b. Atomic mass d. Atomic radius 3

Name: NaF MgO Boiling Point ( C) 1695 3600 Ionic Radius (pm) Na + Mg 2+ F Cl O 2 76 72 133

Based on the data in the tables above, which of the following statements provides the best

NaCl will have a lower boiling point than NaF because coulombic attractions are weaker in

NaCl will have a boiling point between that of NaF and MgO because the covalent character of

NaCl will have a higher boiling point than MgO because the ions are spaced farther apart in

NaCl will have a higher boiling point than MgO because the energy required to transfer

Identify the hybridization around each of the carbon atoms in H 2 C = C = CH 2 a.

4 Name: NaF MgO Boiling Point ( C) Ionic Radius (pm) Na + Mg 2+ F Cl O Based on the data in the tables above, which of the following statements provides the best prediction for the boiling point of NaCl? a. NaCl will have a lower boiling point than NaF because coulombic attractions are weaker in NaCl than in NaF. b. NaCl will have a boiling point between that of NaF and MgO because the covalent character of the bonds in NaCl is intermediate between that of MgO and NaF. c. NaCl will have a higher boiling point than MgO because the ions are spaced farther apart in NaCl. d. NaCl will have a higher boiling point than MgO because the energy required to transfer electrons from the anion to the cation is larger in NaCl than MgO. 26. Identify the hybridization around each of the carbon atoms in H 2 C = C = CH 2 a. sp, sp 2, sp c. sp 3, sp 3, sp 2 b. sp 2, sp 3, sp 2 d. sp 2, sp, sp What is the percentage yield of O 2 if 12.3 g of KClO 3 (molar mass 123 g) is decomposed to produce 3.2 g of O 2 (molar mass 32 g) according to the equation below? 2KClO 3(s) 2KCl (s) 3O 2(g) a. 100% c. 50% b. 67% d. 33% 28. Which of the following graphs correctly shows the relationship between potential energy and internuclear separation for two hydrogen atoms? a. c. b. d. 4

5 Name: Free Response - Show your answers on a separate paper. 29. There are three possible structures fo the cyanate ion, NCO-. a.) Draw the three Lewis Structures and find the formal charges for each atom. b.) Which structure is most likely and why? 30. Draw representations of the following two ionic solids as networks consisting of twelve ions in total. Show the relative differences in the sizes of the ions and the charge on each ion. Identify which ionic solid will have the higher melting temperature and justify your answer. CaO vs CaCl a.) Draw the Lewis electron-dot structures for CO 2-3, CO 2 and CO, including resonance structures where appropriate. b.) What are the effective bond orders for the C-O bonds in each of the three species? c.) Rank the species by C-O bond length? Justify your ranking in terms of bond order and electron density. d.) Which species has the highest bond energy? Justify in terms of bond order and electron density. e.)which species has the highest potential energy? Justify in terms of bond order and electron density. f.) Predict the molecular shapes of each and explain how you arrived at your predictions. g.) What are the hybridized orbitals for each? h.) State the number of sigma and pi bonds each molecule has. i.) Which molecules are polar or nonpolar? Justfiy with a discussion of dipole moments. 32. Which bond for the following set is most ionic? Justify your answer in terms of electronegativity. KCl or FeO 33. Consider the molecules SF 2 and CF 4. a.) Draw Lewis structures for each of the two structures. Include all valence electrons in the two drawings. b.)what is the shape of the SF 2 structure, and what is the approximate F-S-F bond angle? c.) What is the shape of the CF 4 structure and what is the approximate F-C-F bond angle? d.) Which structure is polar and and which is non-polar? Justify your answer. e.) Identify the type of hybrid orbitals for the F-S bond and the F-C bond. 34. a.) Identify the lithium and fluorine ions in the picture of LiF above. b.) How would the picture be different if it was KBr? c.) Which ionic compound, LiF or KBr would have a lower melting point? Justify your answer. 35. NO 2 NO 2 - NO 2 + Nitrogen is the central atom in each of the species given above. a.) Draw the Lewis electron-dot structure for each of the three species. b.) Draw and label the molecular geometry of each. c.) List the species in order of increasing bond angle. Justfy your answer. d.) Give the hybridization of the nitrogen atom in each structure. 5

6 Unit-3 Chemical Bonding Practice Exam Answer Section MULTIPLE CHOICE 1. ANS: B LO 1.15 Cory 2. ANS: B 3. ANS: C NOT: Chem Bond II MCQ P 6 4. ANS: B PTS: 2 5. ANS: B PTS: 2 6. ANS: B 7. ANS: C LO ANS: D diff in EN between O - H is = 1.4 ; diff in EN between P - H is 0 a, c, symmetrical, c NOT: Chem Bond II MC! P 4 9. ANS: C 10. ANS: D NOT: Chem Bond II MCQ P ANS: A 12. ANS: A NOT: Chem Bond MCQ II P ANS: C 14. ANS: B AP Exam Question from Cory s test BI2 LO ANS: C 16. ANS: C NOT: Chem Bond MCQ II P ANS: D PTS: ANS: B NOT: Chem Bond II MCQ P ANS: D NOT: Chem Bond MCQ II P5 20. ANS: D NOT: Chem Bond II MCQ P ANS: D PTS: ANS: C LO 2.21 Cory s BI 2 test 23. ANS: C NOT: Chem Bond MCQII #3 1

7 24. ANS: D LO 1.9 Cory 25. ANS: A 26. ANS: D NOT: Chem Bond II MCQ P ANS: B PTS: ANS: D PTS: 2 SHORT ANSWER 29. ANS: x OBJ: 2.21 NOT: Chem bond II #5 30. ANS: CaO +2, -2 OBJ: 2.19, 2.23, 2.24 NOT: Chem Bond I #7d. 31. ANS: The first part of this question is from AP Exam 1982D 32. ANS: x OBJ: 1.0, 2.18 NOT: Chem bond I #12b 33. ANS: x 34. ANS: Li - smaller, F larger 35. ANS: AP Exam 1992 D 2

8 Name: Class: _ Date: _ Unit-3 Chemical Bonding Practice Exam Multiple Choice - NO CALCULATORS, show your work and justify your answers. 1. The concentration of a red colored solution of cobalt ions needs to be determined. What spectroscopic technique would be the best choice? a. Photoelectron spectroscopy because the electron arrangement is responsible for the color b. UV-Vis spectroscopy because the solution has a color c. Infrared spectroscopy because the solution is red d. Mass spectrometry because knowing the mass allows for calculation of concentration Element Atomic Radius First Ionization Energy Calcium 194 pm 590 kj/mol Potassium 2. Based on periodic trends and the data in the table above, which of the following are the most probable values of the atomic radius and the first ionization energy for potassium, respectively? a. 242 pm, 633 kj/mol c. 120 pm, 633 kj/mol b. 242 pm, 419 kj/mol d. 120 pm, 419 kj/mol 3. Which of the following structures does not have a planar geometry? a. XeF 4 c. NO - 3 b. BF 3 d. SO 3 The next three questions refer to the following gaseous molecules. (A) BeCl2 (B) SO2 (C) N2 (D) O2 4. Is a polar molecule. a. A c. C b. B d. D 5. Is best represented by two or more resonance forms a. A c. C b. B d. D 6. What properites listed below are true of ionic compounds? I. Electrons are shared between bonding atoms II. High melting points III. High volatility IV. Malleable V. Brittle - breaking when ions of like charge aline. VI. Higher concentration in water results in lower electrical current. a. All listed are properites of ionic c. Only I., III, IV compounds b. Only II, V d. Only II, III, VI 1

9 Name: 7. Under which of the following conditions of temperature and pressure will H 2 gas be expected to behave most like an ideal gas? a. 50 K and 0.10 atm c. 500 K and 0.10 atm b. 50 K and 5.0 atm d. 500 K and 50 atm 8. Which of the following molecules has the largest dipole moment? a. CH 4 c. PF 5 b. PH 3 d. H 2 O 9. Which of the following structures have a linear geometry? I. XeF 2 II. IF - 2 III. CO 2 a. I only c. III only b. II only d. II and III 10. How many sigma and pi bonds are there in C 2 H 4? a. 1 sigma and 1 pi c. 4 sigma and 2 pi b. 4 sigma and 1 pi d. 5 sigma and 1 pi 11. Covalent bonds between two atoms are more polar when a. there is a large difference in c. electrons are transferred, not shared electronegativity b. electrons are shared equally d. electronegativities are the same 12. What are the formal charges on the N, C, S a. 0, 0, -1 c. 0, -1, 0 b. -1, 0, 0 d. 5, 4, Which bond has the highest bond order? a. single c. triple b. double d. ionic 14. C 2 H 2(g) + Cl 2(g) -> C 2 H 2 Cl 2(g) When the reaction above occurs, does the hybridization of the carbon atoms change? a. Yes; it changes from sp to sp2. b. Yes; it changes from sp to sp3. c. Yes; it changes from sp2 to sp3. d. No, it does not change. 15. N 2 molecules absorb ultraviolet light but not visible light. I 2 molecules absorb both visible and ultraviolet light. Which of the following statements explains the observations? a. More energy is required to make N 2 molecules vibrate than is required to make I 2 molecules vibrate. b. More energy is required to remove an electron from an I 2 molecule than is required to remove an electron from a N 2 molecule. c. Visible light does not produce transitions between electronic energy levels in the N 2 molecule but does produce transitions in the I 2 molecule. d. The molecular mass of I 2 is greater than the molecular mass of N 2. 2

10 Name: 16. Which of the following bonds has the longest bondlength? a. N - O c. N - Br b. N - F d. N - Cl 17. Which of the following is LEAST likely to exist? a. PCl 5 c. NF 3 b. PBr 3 d. NI Which compound has the highest melting point? a. NaF c. MgO b. Al 2 O 3 d. CaF Which of the following molecules is polar? a. CO 2 c. BF 3 b. CH 4 d. CH 3 F 20. Which bond below is least ionic? a. Ca - Cl c. N - O b. Al - F d. C - H 21. Which of the following molecules is nonpolar but has polar covalent bonds? a. N 2 c. H 2 O b. H 2 O 2 d. CCl Lewis electron-dot diagrams for CO 2 and SO 2 are given above. The molecular geometry and polarity of the two substances are a. the same because the molecular formulas are similar c. different because the lone pair of electrons on the S atom make it the b. the same because C and S have similar electronegativity values negative end of a dipole d. different because S has a greater number of electron domains (regions of electron density) surrounding it than C has 23. The central atom in a molecule displays sp 3 hybridization. What shape do the charge clouds make? a. Linear c. Tetrahedral b. Trigonal Planar d. Square pyramidal 24. Which of the following properties generally decreases across the periodic table from sodium to chlorine? a. First ionization energy c. Electronegativity b. Atomic mass d. Atomic radius 3

11 Name: NaF MgO Boiling Point ( C) Ionic Radius (pm) Na + Mg 2+ F Cl O Based on the data in the tables above, which of the following statements provides the best prediction for the boiling point of NaCl? a. NaCl will have a lower boiling point than NaF because coulombic attractions are weaker in NaCl than in NaF. b. NaCl will have a boiling point between that of NaF and MgO because the covalent character of the bonds in NaCl is intermediate between that of MgO and NaF. c. NaCl will have a higher boiling point than MgO because the ions are spaced farther apart in NaCl. d. NaCl will have a higher boiling point than MgO because the energy required to transfer electrons from the anion to the cation is larger in NaCl than MgO. 26. Identify the hybridization around each of the carbon atoms in H 2 C = C = CH 2 a. sp, sp 2, sp c. sp 3, sp 3, sp 2 b. sp 2, sp 3, sp 2 d. sp 2, sp, sp What is the percentage yield of O 2 if 12.3 g of KClO 3 (molar mass 123 g) is decomposed to produce 3.2 g of O 2 (molar mass 32 g) according to the equation below? 2KClO 3(s) 2KCl (s) 3O 2(g) a. 100% c. 50% b. 67% d. 33% 28. Which of the following graphs correctly shows the relationship between potential energy and internuclear separation for two hydrogen atoms? a. c. b. d. 4

12 Name: Free Response - Show your answers on a separate paper. 29. There are three possible structures fo the cyanate ion, NCO-. a.) Draw the three Lewis Structures and find the formal charges for each atom. b.) Which structure is most likely and why? 30. Draw representations of the following two ionic solids as networks consisting of twelve ions in total. Show the relative differences in the sizes of the ions and the charge on each ion. Identify which ionic solid will have the higher melting temperature and justify your answer. CaO vs CaCl a.) Draw the Lewis electron-dot structures for CO 2-3, CO 2 and CO, including resonance structures where appropriate. b.) What are the effective bond orders for the C-O bonds in each of the three species? c.) Rank the species by C-O bond length? Justify your ranking in terms of bond order and electron density. d.) Which species has the highest bond energy? Justify in terms of bond order and electron density. e.)which species has the highest potential energy? Justify in terms of bond order and electron density. f.) Predict the molecular shapes of each and explain how you arrived at your predictions. g.) What are the hybridized orbitals for each? h.) State the number of sigma and pi bonds each molecule has. i.) Which molecules are polar or nonpolar? Justfiy with a discussion of dipole moments. 32. Which bond for the following set is most ionic? Justify your answer in terms of electronegativity. KCl or FeO 33. Consider the molecules SF 2 and CF 4. a.) Draw Lewis structures for each of the two structures. Include all valence electrons in the two drawings. b.)what is the shape of the SF 2 structure, and what is the approximate F-S-F bond angle? c.) What is the shape of the CF 4 structure and what is the approximate F-C-F bond angle? d.) Which structure is polar and and which is non-polar? Justify your answer. e.) Identify the type of hybrid orbitals for the F-S bond and the F-C bond. 34. a.) Identify the lithium and fluorine ions in the picture of LiF above. b.) How would the picture be different if it was KBr? c.) Which ionic compound, LiF or KBr would have a lower melting point? Justify your answer. 35. NO 2 NO 2 - NO 2 + Nitrogen is the central atom in each of the species given above. a.) Draw the Lewis electron-dot structure for each of the three species. b.) Draw and label the molecular geometry of each. c.) List the species in order of increasing bond angle. Justfy your answer. d.) Give the hybridization of the nitrogen atom in each structure. 5

13 Unit-3 Chemical Bonding Practice Exam Answer Section MULTIPLE CHOICE 1. ANS: B LO 1.15 Cory 2. ANS: B 3. ANS: C NOT: Chem Bond II MCQ P 6 4. ANS: B PTS: 2 5. ANS: B PTS: 2 6. ANS: B 7. ANS: C LO ANS: D diff in EN between O - H is = 1.4 ; diff in EN between P - H is 0 a, c, symmetrical, c NOT: Chem Bond II MC! P 4 9. ANS: C 10. ANS: D NOT: Chem Bond II MCQ P ANS: A 12. ANS: A NOT: Chem Bond MCQ II P ANS: C 14. ANS: B AP Exam Question from Cory s test BI2 LO ANS: C 16. ANS: C NOT: Chem Bond MCQ II P ANS: D PTS: ANS: B NOT: Chem Bond II MCQ P ANS: D NOT: Chem Bond MCQ II P5 20. ANS: D NOT: Chem Bond II MCQ P ANS: D PTS: ANS: C LO 2.21 Cory s BI 2 test 23. ANS: C NOT: Chem Bond MCQII #3 1

14 24. ANS: D LO 1.9 Cory 25. ANS: A 26. ANS: D NOT: Chem Bond II MCQ P ANS: B PTS: ANS: D PTS: 2 SHORT ANSWER 29. ANS: x OBJ: 2.21 NOT: Chem bond II #5 30. ANS: CaO +2, -2 OBJ: 2.19, 2.23, 2.24 NOT: Chem Bond I #7d. 31. ANS: The first part of this question is from AP Exam 1982D 32. ANS: x OBJ: 1.0, 2.18 NOT: Chem bond I #12b 33. ANS: x 34. ANS: Li - smaller, F larger 35. ANS: AP Exam 1992 D 2

AP Chemistry- Practice Bonding Questions for Exam

AP Chemistry- Practice Bonding Questions for Exam Multiple Choice Identify the choice that best completes the statement or answers the question. 1. Which of the following is a correct Lewis structure for