Test Bank Chapter 6 Fundamentals Of Chemical Bonding 248

CHAPTER 6

FUNDAMENTALS OF CHEMICAL BONDING

CHAPTER STUDY OBJECTIVES

1. Use the concept of electronegativity to determine the polarity of a chemical bond.

SKILLS TO MASTER: Using electronegativity differences to assess bond polarity

KEY CONCEPTS: A covalent bond arises from the mutual attraction of the bonding electrons to the two nuclei. A greater difference in electronegativity leads to a more polar bond.

2. Draw optimized Lewis structures of covalent compounds, including resonance structures.

SKILLS TO MASTER: Following the four steps for drawing a provisional Lewis structure; optimizing the configuration of the inner atoms; calculating formal charges Identifying and drawing resonance structures

KEY CONCEPTS: Only the valence electrons appear in a Lewis structure. Most atoms other than hydrogen are most stable when associated with an octet of electrons. The most likely Lewis structure has the lowest formal charges.

3. Recognize the importance of the tetrahedral shape in molecules.

SKILLS TO MASTER: Predicting the shapes of molecules that have a steric number of 4

KEY CONCEPTS: An electron group can be two electrons in a single bond, four electrons in a double bond, six electrons in a triple bond, a pair of non-bonding electrons, or a single electron. The steric number of an inner atom is the sum of the number of ligands plus the number of lone pairs. Molecular shape describes how the ligands, not the electron groups, are arranged in space. Molecular shapes can be derived from the steric number and number of ligands bonded to a central atom.

4. Use the VSEPR model to predict the shapes of molecules with steric numbers 2, 3, 5, and 6.

SKILLS TO MASTER: Predicting the shapes of molecules that have a steric number of 2; predicting the shapes of molecules that have a steric number of 3; predicting the shapes of molecules that have a steric number of 5; predicting the shapes of molecules that have a steric number of 6

5. Understand the factors that influence bond angles, lengths, and energies.

KEY CONCEPTS: Electron–electron repulsion generated by non-bonding pairs is always greater than that generated by bonding pairs. Dipole moments are affected by electronegativity differences and molecular geometry. Bond lengths are affected by atomic radii, bond multiplicity, effective nuclear charges, and electronegativity differences.

Multiple Choice QUESTIONS

1. Which of the following is the most important component of formation of a H–Br bond?

a)

b)

c)

d)

e)

Difficulty: Easy

Learning Objective: Use the concept of electronegativity to determine the polarity of a chemical bond.

Section Reference: 6.1 Overview of Bonding

2. Which of the following ranks the atoms in order of decreasing electronegativity?

a) Cl, O, Te, Mo, Rb

b) O, Cl, Mo, Rb, Te

c) Cl, O, Mo, Rb, Te

d) Rb, Mo, Te, Cl, O

e) O, Cl, Te, Mo, Rb

Difficulty: Easy

Learning Objective: Use the concept of electronegativity to determine the polarity of a chemical bond.

Section Reference: 6.1 Overview of Bonding

Feedback: Most electronegative atoms are found at the top right hand of the periodic table; metals have lower EN, non-metals tend to have higher EN.

3. Which of the following ranks the atoms in order of increasing electronegativity?

a) F, Cl, O, C, Br

b) C, Br, Cl, O, F

c) F, O, Cl, Br, C

d) C, Br, O, Cl, F

e) C, O, Br, Cl, F

Difficulty: Medium

Learning Objective: Use the concept of electronegativity to determine the polarity of a chemical bond.

Section Reference: 6.1 Overview of Bonding

Feedback: Recognize that F is most EN, and that oxygen more EN than Cl

4. Which of the following ranks the following bonds from most polar to least polar?

Cl–O, Mg–O, O–O, C–O

a) Mg–O>Cl–O>C–O>O–O

b) Cl–O>Mg–O> C–O>O–O

c) Cl–O> C–O> Mg–O> O–O

d) Mg–O> C–O> Cl–O>O–O

e) Mg–O>Cl–O>O–O> C–O

Difficulty: Medium

Learning Objective: Use the concept of electronegativity to determine the polarity of a chemical bond.

Section Reference: 6.1 Overview of Bonding

5. Which of the following bonds is polar covalent?

a) LiF

b) Cl–Cl

c) Br–I

d) C–Cl

e) LiCl

Difficulty: Easy

Learning Objective: Use the concept of electronegativity to determine the polarity of a chemical bond.

Section Reference: 6.1 Overview of Bonding

6. Which of the following bonds is ionic?

a) Li–F

b) Cu–Zn

c) Br–I

d) C–Cl

e) C–O

Difficulty: Easy

Learning Objective: Use the concept of electronegativity to determine the polarity of a chemical bond.

Section Reference: 6.1 Overview of Bonding

7. Which of the following bonds is the least polar, but is still slightly polar?

a) Li–F

b) Fe–O

c) Br–I

d) C–C

e) C–I

Difficulty: Medium

Learning Objective: Use the concept of electronegativity to determine the polarity of a chemical bond.

Section Reference: 6.1 Overview of Bonding

8. Arrange the following in order of increasing electronegativity, C, O, F, Br, Ca.

a) C < O < F < Br < Ca

b) Ca < C < O < F < Br

c) Ca < C < Br < O < F

d) Ca < C < O < Br < F

e) Ca < O < C < Br < F

Difficulty: Medium

Learning Objective: Use the concept of electronegativity to determine the polarity of a chemical bond.

Section Reference: 6.1 Overview of Bonding

9. How many valence electrons are in the molecule acetic acid, CH₃CO₂H?

a) 8

b) 12

c) 16

d) 20

e) 24

Difficulty: Easy

Learning Objective: Draw optimized Lewis structures of covalent compounds, including resonance structures.

Section Reference: 6.2 Lewis Structures

10. How many valence electrons are in the phosphate ion, PO₄^-3?

a) 12

b) 24

c) 28

d) 32

e) 36

Difficulty: Easy

Learning Objective: Draw optimized Lewis structures of covalent compounds, including resonance structures.

Section Reference: 6.2 Lewis Structures

11. What are the formal charges on the atoms in the following Lewis structure for HNO₃?

a) 1; 0; 0; 0; –1

b) 0; 0; 1; 0; –1

c) 1; 0; 1; 0; –2

d) 0; 0; 0; 0; 0

e) 0; 0; 0; 1; –1

Difficulty: Medium

Learning Objective: Draw optimized Lewis structures of covalent compounds, including resonance structures.

Section Reference: 6.2 Lewis Structures

12. Which of the following is NOT an important resonance structure for the nitrate ion?

a)

b)

c)

d)

Difficulty: Easy

Learning Objective: Draw optimized Lewis structures of covalent compounds, including resonance structures.

Section Reference: 6.2 Lewis Structures

13. What can you change when drawing resonance structures?

a) total number of bonds

b) total number atoms

c) total number of electrons

d) total number of protons

e) nature of the bonds

Difficulty: Easy

Learning Objective: Draw optimized Lewis structures of covalent compounds, including resonance structures.

Section Reference: 6.2 Lewis Structures

14. How many valence electrons are there in the MnO₄^-?

a) 24

b) 32

c) 30

d) 28

e) 31

Difficulty: Easy

Learning Objective: Draw optimized Lewis structures of covalent compounds, including resonance structures.

Section Reference: 6.2 Lewis Structures

Feedback: a) only included electrons on oxygen; b) correct answer; c) 1 fewer electron than that of atoms; d) s electrons on Mn not included in total; e) did not add additional electron due to negative charge

15. Identify the central atom in the Lewis structure of thionyl chloride, SOCl₂ and explain basis of decision.

a) O, because it is most electronegative

b) S, because it is least electronegative

c) S, because it is largest

d) Cl, because there are two

e) O, because it is smallest

Difficulty: Easy

Learning Objective: Draw optimized Lewis structures of covalent compounds, including resonance structures.

Section Reference: 6.2 Lewis Structures

16. What is the formal charge on Mn in the MnO₄^- ion?

a) 0

b) 1

c) 3

d) 5

e) 7

Difficulty: Medium

Learning Objective: Draw optimized Lewis structures of covalent compounds, including resonance structures.

Section Reference: 6.2 Lewis Structures

17. Which of the following does not have a steric number of 4?

a) water

b) methane

c) ammonia

d) carbon dioxide

e) hydronium ion

Difficulty: Easy

Learning Objective: Recognize the importance of the tetrahedral shape in molecules.

Section Reference: 6.3 Molecular Shapes: Tetrahedral Systems

18. Hydridotributyltin, SnH(CH₂CH₂CH₂CH₃)₃, is used in chemical syntheses. How many atoms in this molecule have tetrahedral geometry?

a) 5

b) 7

c) 9

d) 13

e) 15

Difficulty: Hard

Learning Objective: Recognize the importance of the tetrahedral shape in molecules.

Section Reference: 6.3 Molecular Shapes: Tetrahedral Systems

19. Dimethyl hydrazine, (CH₃)₂N–NH₂, is a liquid at room temperature. How many atoms in this molecule have tetrahedral geometry?

a) 1

b) 2

c) 3

d) 4

e) 5

Difficulty: Hard

Learning Objective: Recognize the importance of the tetrahedral shape in molecules.

Section Reference: 6.3 Molecular Shapes: Tetrahedral Systems

20. Dimethyl hydrazine, (CH₃)₂N–NH₂, is a liquid at room temperature. How many atoms in this molecule have trigonal pyramidal geometry?

a) 1

b) 2

c) 3

d) 4

e) 5

Difficulty: Hard

Learning Objective: Recognize the importance of the tetrahedral shape in molecules.

Section Reference: 6.3 Molecular Shapes: Tetrahedral Systems

21. How many ligands are around the nitrogen atom in the molecule methylamine, CH₃NH₂?

a) 1

b) 2

c) 3

d) 4

e) 5

Difficulty: Easy

Learning Objective: Recognize the importance of the tetrahedral shape in molecules.

Section Reference: 6.3 Molecular Shapes: Tetrahedral Systems

22. What is the steric number for the central atom in the molecule iodine triflouride, IF₃?

a) 1

b) 2

c) 3

d) 4

e) 5

Difficulty: Medium

Learning Objective: Use the VSEPR model to predict the shapes of molecules with steric numbers 2, 3, 5, and 6.

Section Reference: 6.4 Other Molecular Shapes

23. What are the steric number and shape of thionyl chloride, SOCl₂?

a) 3, trigonal planar

b) 3, trigonal pyramidal

c) 4, trigonal pyramidal

d) 4, square pyramidal

e) 4, tetrahedral

Difficulty: Medium

Learning Objective: Use the VSEPR model to predict the shapes of molecules with steric numbers 2, 3, 5, and 6.

Section Reference: 6.4 Other Molecular Shapes

24. What is the molecular shape of the oxyanions of chlorine: ClO^-, ClO₂^-, ClO₃^- and ClO₄^-?

a) bent, bent, trigonal planar, tetrahedral

b) linear, linear, trigonal planar, tetrahedral

c) linear, bent, trigonal planar, tetrahedral

d) linear, bent, trigonal pyramidal, tetrahedral

e) linear, linear, trigonal pyramidal, tetrahedral

Difficulty: Medium

Learning Objective: Use the VSEPR model to predict the shapes of molecules with steric numbers 2, 3, 5, and 6.

Section Reference: 6.4 Other Molecular Shapes

Feedback: must draw Lewis structures for all four molecules and determine the steric number for each

25. What are the approximate bond angles in 1,2 dichloroethene?

a) 109.5

b) 90

c) 120

d) 115

e) 100

Difficulty: Easy

Learning Objective: Understand the factors that influence bond angles, lengths, and energies.

Section Reference: 6.5 Properties of Covalent Bonds

26. Which of the following compounds (CO₂, O₃, SO₂, CS₂) are polar?

a) CO₂, SO₂, CS₂

b) CO₂, O₃, SO₂, CS₂

c) CO₂, SO₂

d) O₃, CS₂

e) O₃, SO₂

Difficulty: Medium

Learning Objective: Understand the factors that influence bond angles, lengths, and energies.

Section Reference: 6.5 Properties of Covalent Bonds

27. Which of the following compounds (CH₄, CH₃Cl, CH₂Cl₂, CHCl₃ and CCl₄) are polar?

a) CCl₄, CHCl₃, CH₃Cl

b) CHCl₃, CH₃Cl

c) CHCl₃, CH₂Cl_2, CH₃Cl

d) CHCl₃, CH₂Cl_2, CH₃Cl, CCl₄

e) CHCl₃

Difficulty: Medium

Learning Objective: Understand the factors that influence bond angles, lengths, and energies.

Section Reference: 6.5 Properties of Covalent Bonds

Feedback: You must consider the shape of the molecule as well as the bond moments.

28. Which of the following molecules has a dipole moment?

a) SiCl₄

b) AlI₃

c) TeCl₄

d) PCl₅

e) CO₂

Difficulty: Medium

Learning Objective: Understand the factors that influence bond angles, lengths, and energies.

Section Reference: 6.5 Properties of Covalent Bonds

29. In which of the following molecules will the bond angle be distorted from the ideal geometric values?

1. SF₅⁺

2. ICl₃

3. BrF₅

4. Si(CH₃)₄

5. PF₅

a) 1, 2, and 3

b) 3 and 5

c) 2, 3, and 4

d) 4 and 5

e) 2 and 3

Difficulty: Hard

Learning Objective: Understand the factors that influence bond angles, lengths, and energies.

Section Reference: 6.5 Properties of Covalent Bonds

30. Which of the following will have a dipole moment?

a) SF₆

b) CH₄

c) XeF₄

d) PH₃

e) C₂H₆

Difficulty: Medium

Learning Objective: Understand the factors that influence bond angles, lengths, and energies.

Section Reference: 6.5 Properties of Covalent Bonds

31. Which is the strongest bond?

a) P – P

b) P – F

c) P – Cl

d) P – Br

e) P – I

Difficulty: Medium

Learning Objective: Understand the factors that influence bond angles, lengths, and energies.

Section Reference: 6.5 Properties of Covalent Bonds

Feedback: Recognize that difference in EN contributes to bond strength and that small molecules that have good orbital overlap will also result in strong bonds.

32. Which is the strongest weakest?

a) P – P

b) P – F

c) P – Cl

d) P – Br

e) P – I

Difficulty: Medium

Learning Objective: Understand the factors that influence bond angles, lengths, and energies.

Section Reference: 6.5 Properties of Covalent Bonds

Feedback: I and P have small difference in electronegative and I is a large atom, resulting in a relatively weak bond.

33. Which of the following will not have a dipole moment?

a) H₂O

b) H₂CO

c) CH₃OH

d) SF₆

e) SF₄

Difficulty: Easy

Learning Objective: Understand the factors that influence bond angles, lengths, and energies.

Section Reference: 6.5 Properties of Covalent Bonds

34. Which of the following is the strongest bond?

a)

b)

c)

d)

e)

Difficulty: Easy

Learning Objective: Understand the factors that influence bond angles, lengths, and energies.

Section Reference: 6.5 Properties of Covalent Bonds

ESSAY QUESTIONS

35. Draw a picture showing the interaction of the valence orbitals of lithium atoms in the formation of Li2.

Difficulty: Easy

Learning Objective: Use the concept of electronegativity to determine the polarity of a chemical bond.

Section Reference: 6.1 Overview of Bonding

36. Draw a picture showing the interaction of the valence orbitals of Cl and Br in the formation of BrCl.

Difficulty: Easy

Learning Objective: Use the concept of electronegativity to determine the polarity of a chemical bond.

Section Reference: 6.1 Overview of Bonding

37. Draw a diagram of energy vs. distance for the interaction of the H and Br atoms. Include sketches of the relative amounts of overlap of the orbitals. The bond energy of HBr is 363 kJ/mole and the H–Br bond length is 140.8 pm.

Difficulty: Hard

Learning Objective: Use the concept of electronegativity to determine the polarity of a chemical bond.

Section Reference: 6.1 Overview of Bonding

38. Sketch the overlap of the valance orbitals in HF.

Difficulty: Easy

Learning Objective: Use the concept of electronegativity to determine the polarity of a chemical bond.

Section Reference: 6.1 Overview of Bonding

39. Identify the bonding, non-bonding, and core orbitals in HBr.

Difficulty: Medium

Learning Objective: Use the concept of electronegativity to determine the polarity of a chemical bond.

Section Reference: 6.1 Overview of Bonding

40. Calculate the electronegativity difference between the atoms in the bonds found below and predict which atom would be positively charged:

Χ_O = 3.5, Χ_N = 3.0, Χ_Cl = 3.0, Χ_C = 2.5, Χ_Al = 1.5, Χ_Cs = 0.7

(i) N–O

(ii) Al–C

(iii) Cl–Cs

Difficulty: Easy

Learning Objective: Use the concept of electronegativity to determine the polarity of a chemical bond.

Section Reference: 6.1 Overview of Bonding

41. Draw the Lewis structure of ionic compound sodium sulphite, Na₂SO₃.

Difficulty: Medium

Learning Objective: Draw optimized Lewis structures of covalent compounds, including resonance structures.

Section Reference: 6.2 Lewis Structures

42. Draw the Lewis structure of dichlorodifluoromethane, CF₂Cl₂.

Difficulty: Easy

Learning Objective: Draw optimized Lewis structures of covalent compounds, including resonance structures.

Section Reference: 6.2 Lewis Structures

43. Draw the Lewis structure and determine the formal charge on the central atom for BF₅.

Difficulty: Easy

Learning Objective: Draw optimized Lewis structures of covalent compounds, including resonance structures.

Section Reference: 6.2 Lewis Structures

44. Draw the three most important resonance structures for the carbonate ion, CO₃^2-.

Difficulty: Medium

Learning Objective: Draw optimized Lewis structures of covalent compounds, including resonance structures.

Section Reference: 6.2 Lewis Structures

45. Draw 2 important resonance structures of the thiocyanate ion, NCS^-1.

Difficulty: Medium

Learning Objective: Draw optimized Lewis structures of covalent compounds, including resonance structures.

Section Reference: 6.2 Lewis Structures

46. Draw 3 resonance structures for N₂O, otherwise known as laughing gas.

Difficulty: Medium

Learning Objective: Draw optimized Lewis structures of covalent compounds, including resonance structures.

Section Reference: 6.2 Lewis Structures

47. Draw Lewis structure of KF₂.

Difficulty: Medium

Learning Objective: Draw optimized Lewis structures of covalent compounds, including resonance structures.

Section Reference: 6.2 Lewis Structures

48. Draw the Lewis structure for thionyl chloride, SOCl₂.

Difficulty: Medium

Learning Objective: Draw optimized Lewis structures of covalent compounds, including resonance structures.

Section Reference: 6.2 Lewis Structures

49. Draw the Lewis structure of methylamine, H₃C–NH₂.

Difficulty: Easy

Learning Objective: Draw optimized Lewis structures of covalent compounds, including resonance structures.

Section Reference: 6.2 Lewis Structures

50. Draw the two structural isomers of C₂H₃Cl₃.

Difficulty: Medium

Learning Objective: Recognize the importance of the tetrahedral shape in molecules.

Section Reference: 6.3 Molecular Shapes: Tetrahedral Systems

51. Draw a ball and stick model that shows the structure of methylamine, H₃CNH₂.

Difficulty: Easy

Learning Objective: Recognize the importance of the tetrahedral shape in molecules.

Section Reference: 6.3 Molecular Shapes: Tetrahedral Systems

52. Hydroxylamine has the formula NH₂(OH). Write the Lewis structure and state the molecular structure of the inner atoms.

Difficulty: Medium

Learning Objective: Recognize the importance of the tetrahedral shape in molecules.

Section Reference: 6.3 Molecular Shapes: Tetrahedral Systems

53. Hydrogen sulphide has the formula H₂S. Write the Lewis structure and state the structure of the inner atoms.

Difficulty: Easy

Learning Objective: Recognize the importance of the tetrahedral shape in molecules.

Section Reference: 6.3 Molecular Shapes: Tetrahedral Systems

54. Draw the Lewis structure and state the structure of the inner atoms for ClF₃.

Difficulty: Easy

Learning Objective: Use the VSEPR model to predict the shapes of molecules with steric numbers 2, 3, 5, and 6.

Section Reference: 6.4 Other Molecular Shapes

55. Draw the Lewis structure and state the molecular structure of the inner atoms for BrF₅.

Difficulty: Medium

Learning Objective: Use the VSEPR model to predict the shapes of molecules with steric numbers 2, 3, 5, and 6.

Section Reference: 6.4 Other Molecular Shapes

56. Write the Lewis structure and state the molecular structure of the inner atoms for SeCl₄.

Difficulty: Easy

Learning Objective: Use the VSEPR model to predict the shapes of molecules with steric numbers 2, 3, 5, and 6.

Section Reference: 6.4 Other Molecular Shapes

57. Write the Lewis structure and state the molecular structure of the inner atoms for N₂O₄.

Difficulty: Medium

Learning Objective: Use the VSEPR model to predict the shapes of molecules with steric numbers 2, 3, 5, and 6.

Section Reference: 6.4 Other Molecular Shapes

58. Write the Lewis structure and state the molecular structure of the inner atoms for AlCl₃.

Difficulty: Medium

Learning Objective: Use the VSEPR model to predict the shapes of molecules with steric numbers 2, 3, 5, and 6.

Section Reference: 6.4 Other Molecular Shapes

59. Write the Lewis structure and state the molecular structure of the inner atoms for XeO₂F₄.

Difficulty: Easy

Learning Objective: Use the VSEPR model to predict the shapes of molecules with steric numbers 2, 3, 5, and 6.

Section Reference: 6.4 Other Molecular Shapes

60. Write the Lewis structure and state the molecular structure of the inner atoms for O₃.

Difficulty: Easy

Learning Objective: Use the VSEPR model to predict the shapes of molecules with steric numbers 2, 3, 5, and 6.

Section Reference: 6.4 Other Molecular Shapes

61. Draw the two structural isomers of C2H3Cl3 and determine which isomer has the greater dipole moment.

Difficulty: Medium

Learning Objective: Understand the factors that influence bond angles, lengths, and energies.

Section Reference: 6.5 Properties of Covalent Bonds

62. Is the oxygen – oxygen bond longer in molecular oxygen, O₂ or ozone, O₃? Explain.

Difficulty: Medium

Learning Objective: Understand the factors that influence bond angles, lengths, and energies.

Section Reference: 6.5 Properties of Covalent Bonds

63. Draw the Lewis structure and estimate the bond angles for bromine pentafluoride, BrF₅.

Difficulty: Medium

Learning Objective: Understand the factors that influence bond angles, lengths, and energies.

Section Reference: 6.5 Properties of Covalent Bonds

64. Draw the Lewis structure and estimate the bond angles for phosphorous trichloride, PCl₃.

Difficulty: Medium

Learning Objective: Understand the factors that influence bond angles, lengths, and energies.

Section Reference: 6.5 Properties of Covalent Bonds

65. Draw the Lewis structure and estimate the bond angles in methanol, CH₃OH.

Difficulty: Easy

Learning Objective: Understand the factors that influence bond angles, lengths, and energies.

Section Reference: 6.5 Properties of Covalent Bonds

66. Which of the molecules, NH₃ or PH₃, should have the stronger bond and explain why.

Difficulty: Medium

Learning Objective: Understand the factors that influence bond angles, lengths, and energies.

Section Reference: 6.5 Properties of Covalent Bonds

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