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Chemistry Atoms First 1st Edition Burdge Overby – Test bank

Chapter 6: Representing Molecules

1.	The Lewis dot symbol consists of the symbol for the element surrounded by dot(s). What does the symbol represent?
	A)	Electron configuration	D)	Atomic mass
	B)	Valence electrons	E)	Nucleus and core electrons
	C)	Atomic number
	Ans: E Difficulty: Easy

2.	The Lewis dot symbol consists of the symbol for the element surrounded by dot(s). What does the dot or dots represent?
	A)	Electron configuration	D)	Atomic mass
	B)	Valence electrons	E)	Core electrons
	C)	Atomic number
	Ans: B Difficulty: Easy

3.	Which of the following contains ionic bonding?
	A) CO B) SrF₂ C) Al D) OCl₂ E) HCl
	Ans: B Difficulty: Easy

4.	How many electrons are in a single bond?
	A) 0 B) 1 C) 2 D) 4 E) 6
	Ans: C Difficulty: Easy

5.	How many electrons are in a double bond?
	A) 0 B) 1 C) 2 D) 4 E) 6
	Ans: D Difficulty: Easy

6.	How many electrons are in a triple bond?
	A) 0 B) 1 C) 2 D) 4 E) 6
	Ans: E Difficulty: Easy

7.	Arrange the following bonds in order of increasing bond strength.
	A)	C–I < C–Br < C–Cl < C–F	D)	C–I < C–Br < C–F< C–Cl
	B)	C–F < C–Cl < C–Br < C–I	E)	none of these orders is correct
	C)	C–Br < C–I < C–Cl < C–F
	Ans: A Difficulty: Medium

8.	Select the strongest bond in the following group.
	A) C–S B) C–O C) C=C D) CºN E) C–F
	Ans: D Difficulty: Easy

9.	Select the strongest bond in the following group.
	A) C–C B) C–O C) C=C D) CºC E) C–F
	Ans: D Difficulty: Easy

10.	Which is the correct order for increasing bond strength? (1) CºC (2) C=C (3) C–C
	A)	(3) < (2) < (1)	D)	(1) < (3) < (2)
	B)	(3) < (1) < (2)	E)	(2) < (3) < (1)
	C)	(1) < (2) < (3)
	Ans: A Difficulty: Easy

11.	What types of elements undergo covalent bonding?
	A)	1 metal and noble gas	D)	2 Group IA elements
	B)	a nonmetal and a metal	E)	an actinide
	C)	2 nonmetals
	Ans: C Difficulty: Easy

12.	In which of these substances are the atoms held together by polar covalent bonding?
	A) SrCl₂ B) CsCl C) ClF D) TiF₂ E) S₈
	Ans: C Difficulty: Easy

13.	A polar covalent bond would form in which one of these pairs of atoms?
	A) Cl ¾ Cl B) Si ¾ Si C) Ca ¾ Cl D) Cr ¾ Br E) P ¾ Cl
	Ans: E Difficulty: Easy

14.	A nonpolar covalent bond (i.e., pure covalent) would form in which of these pairs of atoms?
	A) Na ¾ Cl B) H ¾ Cl C) Li ¾ Br D) Se ¾ Br E) Br ¾ Br
	Ans: E Difficulty: Easy

15.	Which of these covalent bonds is the most polar (i.e., highest percent ionic character)?
	A) Al ¾ I B) Si ¾ I C) Al ¾ Cl D) Si ¾ Cl E) Si ¾ P
	Ans: C Difficulty: Medium

16.	The covalent bond with the greatest polarity would form in which of these atom pairs?
	A) Br ¾ Br B) S ¾ O C) C ¾ P D) C ¾ O E) B ¾ O
	Ans: E Difficulty: Medium

17.	In which of these pairs of atoms would the bond be the least polar (i.e., lowest percent ionic character)?
	A) C ¾ Cl B) C ¾ C C) C ¾ H D) O ¾ C E) N ¾ C
	Ans: B Difficulty: Medium

18.	Which of these elements has the greatest electronegativity?
	A) Na B) As C) Ga D) Cs E) Sb
	Ans: B Difficulty: Medium

19.	Which of these atoms is the most electronegative?
	A) Li B) Cs C) P D) As E) Ge
	Ans: C Difficulty: Medium

20.	Which of these elements is the least electronegative?
	A) Sr B) V C) Ni D) P E) I
	Ans: A Difficulty: Medium

21.	Which of the following elements is the most electronegative?
	A) S B) Ru C) Si D) Te E) Cs
	Ans: A Difficulty: Medium

22.	Which of the following elements is the least electronegative?
	A) Si B) Se C) S D) Sc E) Sr
	Ans: E Difficulty: Medium

23.	Arrange aluminum, nitrogen, phosphorus and indium in order of increasing electronegativity.
	A)	Al < In < N < P	D)	In < P < Al < N
	B)	Al < In < P < N	E)	None of these orders is correct.
	C)	In < Al < P < N
	Ans: C Difficulty: Medium

24.	Arrange calcium, rubidium, sulfur, and arsenic in order of decreasing electronegativity.
	A)	S > As > Rb > Ca	D)	As > S > Ca > Rb
	B)	S > As > Ca > Rb	E)	None of these orders is correct.
	C)	As > S > Rb > Ca
	Ans: B Difficulty: Medium

25.	Based on electronegativity trends in the periodic table, predict which of the following compounds will have the greatest % ionic character in its bonds.
	A) H₂O B) LiI C) CaO D) RbF E) HCl
	Ans: D Difficulty: Medium

26.	What is the magnitude of the partial positive and partial negative charges in the HBr molecule? (1D = 3.36 ´ 10^–30 C m; 1e^– = 1.6022 ´ 10^–19 C; bond length HBr = 1.41 angstroms; Dipole Moment HBr = 0.82D)
	A)	–0.36 and +0.36	D)	–0.121 and +0.121
	B)	–0.14 and +0.14	E)	–2.73 and +2.73
	C)	–0.273 and +0.273
	Ans: D Difficulty: Medium

27.	What is the magnitude of the partial positive and partial negative charges in the HI molecule? (1D = 3.36 ´ 10^–30 C m; 1e^– = 1.6022 ´ 10^–19 C; bond length HI = 1.61 angstroms; Dipole Moment HI = 0.44 D)
	A)	–0.76 and +0.76	D)	–0.6 and +0.6
	B)	–0.057 and +0.057	E)	–0.911 and +0.911
	C)	–1.22 and +1.22
	Ans: B Difficulty: Medium

28.	The total number of bonding electrons in a molecule of formaldehyde (H₂CO) is
	A) 3 B) 4 C) 6 D) 8 E) 18
	Ans: D Difficulty: Medium

29.	The total number of lone pairs in NCl₃ is
	A) 6 B) 8 C) 9 D) 10 E) 13
	Ans: D Difficulty: Medium

30.	The Lewis structure for CS₂ is:
	A) B) C) D)
	Ans: C Difficulty: Medium

31.	The Lewis structure for a chlorate ion, ClO₃^–, should show ____ single bond(s), ____ double bond(s), and ____ lone pair(s).
	A) 2, 1, 10 B) 3, 0, 9 C) 2, 1, 8 D) 3, 0, 10 E) 2, 1, 9
	Ans: D Difficulty: Difficult

32.	Which of these Lewis structures is incorrect?
	A) a B) b C) c D) d E) e
	Ans: E Difficulty: Difficult

33.	Which of these choices is a correct Lewis structure for ozone, O₃?
	A) a B) b C) c D) d E) e
	Ans: D Difficulty: Medium

34.

Which one of the following Lewis structures is definitely incorrect?

A) a B) b C) c D) d E) e

Ans: B Difficulty: Difficult

35.

Hydrazine, N₂H₄, is a good reducing agent that has been used as a component in rocket fuels. Select its Lewis structure.

A) a B) b C) c D) d E) none of these choices is correct

Ans: C Difficulty: Difficult

36.

Select the correct Lewis structure for nitrogen trifluoride, NF₃.

A) a B) b C) c D) d E) e

Ans: A Difficulty: Medium

37.

Select the correct Lewis structure for NOCl, a reactive material used as an ionizing solvent.

A) a B) b C) c D) d E) none of these choices is correct

Ans: B Difficulty: Difficult

38.	The formal charge on the sulfur atom in the resonance structure of sulfur dioxide which has one single bond and one double bond is
	A) 0 B) +1 C) –1 D) +2 E) –2
	Ans: B Difficulty: Difficult

39.	What is the formal charge on phosphorus in a Lewis structure for the phosphate ion that satisfies the octet rule?
	A) –2 B) –1 C) 0 D) +1 E) +2
	Ans: D Difficulty: Difficult

40.	In the best Lewis structure for the fulminate ion, CNO^–, what is the formal charge on the central nitrogen atom?
	A) +2 B) +1 C) 0 D) –1 E) –2
	Ans: B Difficulty: Difficult

41.	In the Lewis structure of the iodate ion, IO₃^–, that satisfies the octet rule, the formal charge on the central iodine atom is
	A) +2 B) +1 C) 0 D) –1 E) –2
	Ans: A Difficulty: Difficult

42.

Select the Lewis structure for XeO₂F₂ which correctly minimizes formal charges.

A) a B) b C) c D) d E) e

Ans: B Difficulty: Difficult

43.

In the following Lewis structure for ClO₃F, chlorine has a formal charge of ____ and an oxidation number of ____.

A) 7, 7 B) 7, –1 C) 1, 1 D) 1, –1 E) 1, 7

Ans: E Difficulty: Difficult

44.

In which one of the following structures does the central atom have a formal charge of +2?

A) a B) b C) c D) d E) e

Ans: B Difficulty: Difficult

45.

The formal charge on Cl in the structure shown for the perchlorate ion is

A) –2 B) –1 C) 0 D) +1 E) +2

Ans: D Difficulty: Difficult

46.	The number of resonance structures for the sulfur dioxide molecule that satisfy the octet rule is
	A) 1 B) 2 C) 3 D) 4 E) None of these
	Ans: B Difficulty: Difficult

47.	The number of resonance structures for the nitrate ion that satisfy the octet rule is
	A) 1 B) 2 C) 3 D) 4 E) None of these
	Ans: C Difficulty: Difficult

48.	In which one of the following is the best Lewis structure a resonance structure?
	A) SO₃ B) BF₃ C) I₃^– D) SCO (C = central atom) E) SO₃^2–
	Ans: A Difficulty: Difficult

49.	In which one of the following species is the central atom (the first atom in the formula) likely to violate the octet rule?
	A) BF₄^– B) XeO₃ C) SiCl₄ D) NH₃ E) CH₂Cl₂
	Ans: B Difficulty: Difficult

50.	Which of the following atoms can expand its valence shell when bonding?
	A) N B) C C) O D) P E) Al
	Ans: D Difficulty: Medium

51.	Which of these substances will display an incomplete octet in its Lewis structure?
	A) CO₂ B) Cl₂ C) ICl D) NO E) SO₂
	Ans: D Difficulty: Medium

52.	Which of these elements is most likely to exhibit an expanded octet in its compounds?
	A) O B) S C) Na D) C E) N
	Ans: B Difficulty: Medium

53.	Which response includes all the molecules below that do not follow the octet rule? (1) H₂S (2) BCl₃ (3) PH₃ (4) SF₄
	A) (2) and (4) B) (2) and (3) C) (1) and (2) D) (3) and (4) E) (1) and (4)
	Ans: A Difficulty: Difficult

54.	Which of these molecules has an atom with an expanded octet?
	A) HCl B) AsCl₅ C) ICl D) NCl₃ E) Cl₂
	Ans: B Difficulty: Medium

55.	Which molecule has a Lewis structure that does not obey the octet rule?
	A) N₂O B) CS₂ C) PH₃ D) CCl₄ E) NO₂
	Ans: E Difficulty: Medium

56.	Ionic compounds tend to form between metals and nonmetals when electrons are transferred from an element with high ionization energy (metal) to an element with a low electron affinity (nonmetal).
	Ans: False Difficulty: Medium

57.	Lewis theorized the octet rule to describe chemical bonding where atoms lose, gain, or share electrons in order to achieve a noble gas configuration.
	Ans: True Difficulty: Easy

58.	Only valence electrons are shown in the Lewis structure held together by covalent bonds.
	Ans: True Difficulty: Easy

59.	A double bond can not exist between a carbon atom and an oxygen atom.
	Ans: False Difficulty: Easy

60.	A triple bond can not exist between a carbon atom and a hydrogen atom.
	Ans: True Difficulty: Easy

61.	Unshared electrons are always shown in pairs around an atom.
	Ans: False Difficulty: Easy

62.	The octet rule works best for elements in the 3^rd period of the periodic table.
	Ans: False Difficulty: Medium

63.	Multiple bonds are longer than single bonds.
	Ans: False Difficulty: Easy

64.	Single bonds are stronger than multiple bonds.
	Ans: False Difficulty: Easy

65.	What theory describes atoms losing, gaining, or sharing electrons to achieve a noble gas configuration?
	Ans:	octet rule
	Difficulty: Easy

66.	What is the distance between the nuclei of two covalently bonded atoms in a molecule?
	Ans:	bond length
	Difficulty: Easy

67.	What term describes the ability of an atom in a compound to pull the electrons to itself?
	Ans:	electronegativity
	Difficulty: Easy

68.	How many lone pairs of electrons are on the central atom in the Lewis structure for NH₃?
	Ans:	1
	Difficulty: Easy

69.	Give the equation for percent ionic character.
	Ans:	(observed dipole moment/calculated dipole moment assuming discrete charges) ´ 100%
	Difficulty: Medium

70.	Give the equation for formal charge.
	Ans:	# valence electrons – (1/2)(bonded electrons) – lone electrons
	Difficulty: Medium

71.	The number of dots in the Lewis dot symbol for a main group element is the same as the ___________ ___________.
	Ans:	group number
	Difficulty: Easy

72.	___________ ___________ of atoms interact to form compounds.
	Ans:	Valence electrons
	Difficulty: Easy

73.	In the Lewis dot symbol, the element symbol represents the ________ _________ and the dots represent the __________ ___________.
	Ans:	core electrons; valence electrons
	Difficulty: Easy

74.	A triple bond arises when two atoms share ___________ pairs of electrons.
	Ans:	three
	Difficulty: Easy

75.	A single bond between two atoms represents ________ pair(s) of electrons
	Ans:	one
	Difficulty: Easy

76.	______________ is a representation of covalent bonding in which shared electron pairs are shown either as dashes or as pairs of dots between two atoms and unshared electrons are shown as dots around the individual atoms.
	Ans:	Lewis structure
	Difficulty: Easy

77.	Using appropriate, real examples to illustrate your answer, describe the correlation between bond energy and bond length for a series of single bonds.
	Ans:	The bonds between carbon, C, and the halogens, X (X = F, Cl, Br, I) can be used as an examples. The size of X increases as one moves down the group. This means that the C–X bond length will become correspondingly longer. As this occurs the bond becomes weaker. Thus, the C–I bond is the longest and weakest, C–F the shortest and strongest of the series.
	Difficulty: Medium

78.	Using appropriate, real examples to illustrate your answer, describe the correlation between bond energy and bond length for a series of varying bond order.
	Ans:	Carbon and oxygen form single, double and triple bonds. The CºO bond in carbon monoxide is roughly three times as strong as the C–O single bond, while the C=O bond is about twice as strong as the single bond. The bond energy is approximately proportional to the bond order.
	Difficulty: Medium

79.	Describe in brief how electronegativity values can be used to predict the percent ionic character of a bond between two atoms.
	Ans:	Take the electronegativity difference (DEN) of the bonded atoms. The larger the difference between their electronegativities, the more ionic will be the nature of the bond. If DEN = 0, the bond will be pure covalent.
	Difficulty: Medium

Chapter 7: Molecular Geometry and Bonding Theories

1.	What does VSEPR model mean?
	A)	Very Specific Electron and Proton Repair model
	B)	Variable Selective of Electron and PRotons
	C)	Valence Shell for Every Proton
	D)	Very Selective Electron PaiR theory
	E)	Valence Shell Electron-Pair Repulsion
	Ans: E Difficulty: Easy

2.	Which of the following is required for determination of the VSEPR model and the molecular shape?
	A)	Atomic mass	D)	Lewis structure
	B)	# of protons	E)	None of the answers is correct
	C)	Oxidation number
	Ans: D Difficulty: Easy

3.	According to the VSEPR theory, the shape of the SO₃ molecule is
	A)	pyramidal.	D)	distorted tetrahedron (seesaw).
	B)	tetrahedral.	E)	square planar.
	C)	trigonal planar.
	Ans: C Difficulty: Medium

4.	What is the molecular shape of the CH₄ molecule?
	A)	tetrahedral.	D)	square planar.
	B)	trigonal pyramidal	E)	distorted tetrahedron (seesaw).
	C)	trigonal planar.
	Ans: A Difficulty: Easy

5.	Use VSEPR theory to predict the shape of the PCl₃ molecule.
	A) linear B) bent C) trigonal planar D) trigonal pyramidal E) tetrahedral
	Ans: D Difficulty: Medium

6.	What is the molecular shape of the H₂O molecule?
	A)	tetrahedral.	D)	square planar.
	B)	trigonal pyramidal	E)	distorted tetrahedron (seesaw).
	C)	bent.
	Ans: C Difficulty: Easy

7.	What is the molecular shape of the IBr₃ molecule?
	A)	tetrahedral.	D)	trigonal planar.
	B)	T-shaped	E)	distorted tetrahedron (seesaw).
	C)	bent.
	Ans: B Difficulty: Medium

8.	According to the VSEPR theory, the molecular shape of the carbonate ion, CO₃^{2 –}, is
	A)	square planar.	D)	trigonal planar.
	B)	tetrahedral.	E)	octahedral.
	C)	pyramidal.
	Ans: D Difficulty: Medium

9.	According to the VSEPR theory, the molecular shape of SiCl₄ is
	A) linear. B) trigonal planar. C) bent. D) tetrahedral. E) trigonal pyramidal.
	Ans: D Difficulty: Easy

10.	According to the VSEPR theory, the molecular shape of ammonia is
	A) linear. B) trigonal planar. C) bent. D) tetrahedral. E) trigonal pyramidal.
	Ans: E Difficulty: Medium

11.	According to the VSEPR theory, which one of the following species should be linear?
	A) H₂S B) HCN C) BF₃ D) H₂CO E) SO₃
	Ans: B Difficulty: Medium

12.	According to VSEPR theory, which one of the following molecules should have a shape that is trigonal bipyramidal?
	A) SF₄ B) XeF₄ C) NF₃ D) SF₆ E) PF₅
	Ans: E Difficulty: Medium

13.	Which one of the following molecules has tetrahedral geometry?
	A) XeF₄ B) BF₃ C) AsF₅ D) CF₄ E) NH₃
	Ans: D Difficulty: Medium

14.	Predict the geometry around the central atom in PO₄^3–.
	A)	trigonal planar.	D)	trigonal bipyramidal.
	B)	trigonal pyramidal.	E)	octahedral.
	C)	tetrahedral.
	Ans: C Difficulty: Medium

15.	Predict the geometry around the central atom in SO₃^2–.
	A)	trigonal planar.	D)	trigonal bipyramidal.
	B)	trigonal pyramidal.	E)	octahedral.
	C)	tetrahedral.
	Ans: B Difficulty: Medium

16.	What is the total number of electron domains for a molecule having a trigonal pyramidal molecular geometry such as NH₃?
	A) 5 B) 2 C) 3 D) 4 E) 6
	Ans: D Difficulty: Medium

17.	What is the total number of electron domains for a molecule having a T-shaped pyramidal molecular geometry such as BrF₃?
	A) 5 B) 2 C) 3 D) 4 E) 6
	Ans: A Difficulty: Medium

18.	What is the total number of electron domains for a molecule having a square pyramidal molecular geometry such as ClF₅?
	A) 5 B) 2 C) 3 D) 4 E) 6
	Ans: E Difficulty: Medium

19.	What is the total number of electron domains for a molecule having a square planar molecular geometry such as XeBr₄?
	A) 5 B) 2 C) 3 D) 4 E) 6
	Ans: E Difficulty: Medium

20.	What is the number of lone electron pairs on the central atom of a molecule having a molecular geometry of seesaw-shaped such as SF₄?
	A) 1 B) 2 C) 3 D) 4 E) 6
	Ans: A Difficulty: Medium

21.	What is the number of lone electron pairs on the central atom of a molecule having a trigonal pyramidal molecular geometry such as NH₃?
	A) 1 B) 2 C) 3 D) 0 E) 4
	Ans: A Difficulty: Medium

22.	What is the number of lone electron pairs on the central atom of a molecule having a linear molecular geometry such as CO₂?
	A) 1 B) 2 C) 3 D) 0 E) 4
	Ans: D Difficulty: Medium

23.	What is the number of lone electron pairs on the central atom of a molecule having a linear molecular geometry such as ClF₂^–?
	A) 1 B) 2 C) 3 D) 0 E) 4
	Ans: C Difficulty: Medium

24.	According to VSEPR theory, a molecule with the general formula AX₃E_o will have a ______ molecular shape.
	A) linear. B) bent. C) trigonal planar. D) tetrahedral. E) trigonal pyramidal.
	Ans: C Difficulty: Medium

25.	According to VSEPR theory, a molecule with the general formula AX₅E_o will have a ______ molecular shape.
	A)	tetrahedral.	D)	trigonal bipyramidal.
	B)	trigonal planar.	E)	see-saw.
	C)	trigonal pyramidal.
	Ans: D Difficulty: Medium

26.	According to VSEPR theory, a molecule with the general formula AX₂E₂ will have a _____ molecular shape.
	A) linear. B) bent. C) trigonal planar. D) tetrahedral. E) see-saw.
	Ans: B Difficulty: Medium

27.	According to VSEPR theory, a molecule with the general formula AX₄E₂ will have a _____ molecular shape.
	A)	tetrahedral.	D)	octahedral.
	B)	square pyramidal.	E)	see-saw.
	C)	square planar.
	Ans: C Difficulty: Medium

28.	According to VSEPR theory, a molecule with the general formula AX₅E will have a ______ molecular shape.
	A)	tetrahedral.	D)	octahedral.
	B)	trigonal bipyramidal	E)	see-saw.
	C)	square pyramidal
	Ans: C Difficulty: Medium

29.

What is the molecular shape of N₂O as predicted by the VSEPR theory?

A) trigonal pyramidal B) trigonal planar C) angular D) bent E) linear

Ans: E Difficulty: Medium

30.	What is the molecular shape of the thiocyanate anion, SCN^–, as predicted by the VSEPR theory? (Carbon is the central atom.)
	A) linear B) bent C) angular D) trigonal E) none of these choices is correct
	Ans: A Difficulty: Medium

31.	What is the molecular shape of BeH₂ as predicted by the VSEPR theory?
	A) linear B) bent C) angular D) trigonal E) none of these choices is correct
	Ans: A Difficulty: Medium

32.

What is the molecular shape of NOCl as predicted by the VSEPR theory?

A) linear B) trigonal planar C) bent D) tetrahedral E) trigonal pyramidal

Ans: C Difficulty: Medium

33.	What is the molecular shape of NO₂^– as predicted by the VSEPR theory?
	A) linear B) trigonal planar C) bent D) tetrahedral E) resonant
	Ans: C Difficulty: Medium

34.	What is the molecular shape of ClO₃F as predicted by the VSEPR theory?
	A)	trigonal pyramidal	D)	tetrahedral
	B)	square planar	E)	octahedral
	C)	square pyramidal
	Ans: D Difficulty: Medium

35.	What is the molecular shape of HOF as predicted by the VSEPR theory?
	A) trigonal pyramidal B) trigonal C) tetrahedral D) linear E) bent
	Ans: E Difficulty: Medium

36.	What is the molecular shape of XeO₂F₂ as predicted by the VSEPR theory?
	A)	square planar	D)	see-saw
	B)	tetrahedral	E)	octahedral
	C)	square pyramidal
	Ans: D Difficulty: Medium

37.	What is the molecular shape of ClF₂^– as predicted by the VSEPR theory?
	A) linear B) bent C) see-saw D) T-shaped E) L-shaped
	Ans: A Difficulty: Medium

38.	What is the molecular shape of SiF₆^2– as predicted by the VSEPR theory?
	A)	trigonal bipyramidal	D)	see-saw
	B)	hexagonal	E)	octahedral
	C)	tetrahedral
	Ans: E Difficulty: Medium

39.	Use VSEPR theory to predict the electron group arrangement around iodine, the central atom in the ion IF₂^–.
	A)	octahedral	D)	trigonal planar
	B)	trigonal bipyramidal	E)	bent
	C)	tetrahedral
	Ans: B Difficulty: Medium

40.	Use VSEPR theory to decide which one of the following molecules and ions will definitely have at least one 90° bond angle in it. (In each case except water, the central atom is the first one in the formula.)
	A) AlCl₄^– B) NH₃ C) PCl₅ D) CO₂ E) H₂O
	Ans: C Difficulty: Medium

41.	What is the approximate bond angle for CCl₄?
	A) 90° B) 109.5° C) 120° D) 145° E) 180°
	Ans: B Difficulty: Easy

42.	The F – S – F bond angles in SF₆ are
	A) 90° and 180° B) 109.5° C) 120° D) 180° E) 90° and 120°
	Ans: A Difficulty: Medium

43.	What is the approximate bond angle for NH₃?
	A) 90° B) 109.5° C) 120° D) 107° E) 105°
	Ans: D Difficulty: Medium

44.	What is the approximate bond angle for CO₂?
	A) 90° B) 109.5° C) 120° D) 107° E) 180°
	Ans: E Difficulty: Medium

45.	What is the approximate bond angle for H₂O?
	A) 90° B) 109.5° C) 120° D) 107° E) 105°
	Ans: E Difficulty: Medium

46.	Predict the ideal bond angles in AsCl₃ using the molecular shape given by the VSEPR theory.
	A) 90° B) 109° C) 120° D) 180° E) between 110 and 120°
	Ans: B Difficulty: Medium

47.	Predict the actual bond angles in BrF₃ using the VSEPR theory.
	A)	more than 120°	D)	between 90° and 109°
	B)	exactly 120°	E)	less than 90°
	C)	between 109° and 120°
	Ans: E Difficulty: Medium

48.	What is the approximate bond angle for CH₄?
	A) 90° B) 109.5° C) 120° D) 107° E) 105°
	Ans: B Difficulty: Easy

49.	How do you describe the molecular geometry of a molecule that does not have a central atom?
	A)	Describe the molecular geometry around the most electronegative atom.
	B)	Describe the molecular geometry around all non-hydrogen atoms.
	C)	Describe the molecular geometry around the most electropositive atom.
	D)	Describe the molecular geometry around the atom with the largest atomic radius.
	E)	Describe the molecular geometry around the atom with the largest bond angle.
	Ans: B Difficulty: Medium

50.	Which one of the following molecules is nonpolar?
	A) NH₃ B) OF₂ C) CH₃Cl D) H₂O E) BeCl₂
	Ans: E Difficulty: Difficult

51.	Complete this sentence: The PCl₅ molecule has
	A)	nonpolar bonds, and is a nonpolar molecule.
	B)	nonpolar bonds, but is a polar molecule.
	C)	polar bonds, and is a polar molecule.
	D)	polar bonds, but is a nonpolar molecule.
	Ans: D Difficulty: Difficult

52.	Which one of the following molecules is nonpolar?
	A) CO₂ B) BF₃ C) KCl D) IBr₃ E) CHCl₃
	Ans: A Difficulty: Difficult

53.	Which one of the following molecules has a zero dipole moment?
	A) CO B) CH₂Cl₂ C) SO₃ D) SO₂ E) NH₃
	Ans: C Difficulty: Difficult

54.	What is the dipole moment for CO₂?
	A)	–1	D)	need more information
	B)	0	E)	None of the answers is correct
	C)	+1
	Ans: B Difficulty: Medium

55.	Which one of the following molecules is polar?
	A) PBr₅ B) CCl₄ C) BrF₅ D) XeF₂ E) XeF₄
	Ans: C Difficulty: Difficult

56.	Predict the molecular geometry and polarity of the SO₂ molecule.
	A)	linear, polar	D)	bent, nonpolar
	B)	linear, nonpolar	E)	None of the above.
	C)	bent, polar
	Ans: C Difficulty: Difficult

57.	Predict the geometry and polarity of the CS₂ molecule.
	A)	linear, polar	D)	bent, nonpolar
	B)	linear, nonpolar	E)	bent, polar
	C)	tetrahedral, nonpolar
	Ans: B Difficulty: Difficult

58.	Which one of the following molecules is polar?
	A) CH₄ B) CHBr₃ C) F₂ D) CBr₄ E) CO₂
	Ans: B Difficulty: Difficult

59.	Which of the following molecules has a net dipole moment?
	A) BeCl₂ B) SF₂ C) KrF₂ D) CO₂ E) CCl₄
	Ans: B Difficulty: Difficult

60.	Which of the following has no net dipole moment?
	A) N₂O B) NF₃ C) H₂Se D) TeO₃ E) CH₃Cl
	Ans: D Difficulty: Difficult

61.	Which of the following atoms, in the ground state, has unpaired electrons?
	A) Ca B) Ne C) Mg D) He E) C
	Ans: E Difficulty: Easy

62.	Which of the following atoms, in the ground state, does not have unpaired electrons?
	A) P B) Na C) Ne D) C E) S
	Ans: C Difficulty: Easy

63.	How many bonds should an oxygen atom form?
	A) 1 B) 2 C) 3 D) 6 E) 4
	Ans: B Difficulty: Easy

64.	How many bonds should a carbon atom form?
	A) 1 B) 2 C) 3 D) 6 E) 4
	Ans: E Difficulty: Easy

65.	How many bonds should a fluorine atom form?
	A) 1 B) 2 C) 3 D) 6 E) 4
	Ans: A Difficulty: Easy

66.	Indicate the type of hybrid orbitals used by the central atom in PCl₃.
	A) sp B) sp² C) sp³ D) sp³d E) sp³d²
	Ans: C Difficulty: Difficult

67.	Indicate the type of hybrid orbitals used by the central atom in CCl₄.
	A) sp B) sp² C) sp³ D) sp³d E) sp³d²
	Ans: D Difficulty: Medium

68.	Indicate the type of hybrid orbitals used by the central atom in SF₆.
	A) sp B) sp² C) sp³ D) sp³d E) sp³d²
	Ans: E Difficulty: Medium

69.	What is the hybridization of the As atom in the AsF₅ molecule?
	A) sp B) sp² C) sp³ D) sp³d E) sp³d²
	Ans: D Difficulty: Medium

70.	What is the hybridization on the central atom in NO₃^–?
	A) sp B) sp² C) sp³ D) sp³d E) sp³d²
	Ans: B Difficulty: Difficult

71.	In which one of the following molecules is the central atom sp² hybridized?
	A) SO₂ B) N₂O C) BeCl₂ D) NF₃ E) PF₅
	Ans: A Difficulty: Difficult

72.	What is the hybridization of As in the AsF₄^– ion?
	A) sp B) sp² C) sp³ D) sp³d E) sp³d²
	Ans: D Difficulty: Difficult

73.	What is the hybridization of the central atom in ClO₃^–?
	A) sp B) sp² C) sp³ D) sp³d E) sp³d²
	Ans: C Difficulty: Difficult

74.	The hybridization of the central nitrogen atom in the molecule N₂O is
	A) sp B) sp² C) sp³ D) sp³d E) sp³d²
	Ans: A Difficulty: Difficult

75.	A molecule with the formula AX₂ uses _________ to form its bonds.
	A)	sp hybrid orbitals	D)	sp³d hybrid orbitals
	B)	sp² hybrid orbitals	E)	sp³d² hybrid orbitals
	C)	sp³ hybrid orbitals
	Ans: A Difficulty: Difficult

76.	A molecule with the formula AX₄ uses _________ to form its bonds.
	A)	sp hybrid orbitals	D)	sp³d hybrid orbitals
	B)	sp² hybrid orbitals	E)	sp³d² hybrid orbitals
	C)	sp³ hybrid orbitals
	Ans: C Difficulty: Difficult

77.	A molecule with the formula AX₄E₂ uses _________ to form its bonds.
	A)	sp hybrid orbitals	D)	sp³d hybrid orbitals
	B)	sp² hybrid orbitals	E)	sp³d² hybrid orbitals
	C)	sp³ hybrid orbitals
	Ans: E Difficulty: Difficult

78.	Carbon uses ______ hybrid orbitals in ClCN.
	A) sp B) sp² C) sp³ D) sp³d E) sp³d²
	Ans: A Difficulty: Difficult

79.	Valence bond theory predicts that carbon will use _____ hybrid orbitals in the carbonate anion, CO₃^2–.
	A) sp B) sp² C) sp³ D) sp³d E) sp³d²
	Ans: B Difficulty: Difficult

80.	Valence bond theory predicts that sulfur will use _____ hybrid orbitals in sulfur dioxide, SO₂.
	A) sp B) sp² C) sp³ D) sp³d E) sp³d²
	Ans: B Difficulty: Difficult

81.	When PCl₅ solidifies it forms PCl₄⁺ cations and PCl₆^–anions. According to valence bond theory, what hybrid orbitals are used by phosphorus in the PCl₄⁺ cations?
	A) sp B) sp² C) sp³ D) sp³d E) sp³d²
	Ans: C Difficulty: Difficult

82.	Valence bond theory predicts that iodine will use _____ hybrid orbitals in ICl₂^–.
	A) sp² B) sp³ C) sp³d D) sp³d² E) none of these choices is correct
	Ans: C Difficulty: Difficult

83.	Which one of the following statements about orbital hybridization is incorrect?
	A)	The carbon atom in CH₄ is sp³ hybridized.
	B)	The carbon atom in CO₂ is sp hybridized.
	C)	The nitrogen atom in NH₃ is sp² hybridized.
	D)	sp² hybrid orbitals are coplanar, and at 120° to each other.
	E)	sp hybrid orbitals lie at 180° to each other.
	Ans: C Difficulty: Difficult

84.	For which one of the following molecules is the indicated type of hybridization not appropriate for the central atom?
	A)	BeCl₂sp²	D)	C₂H₂sp
	B)	SiH₄sp³	E)	H₂O sp³
	C)	BF₃sp²
	Ans: A Difficulty: Difficult

85.	Determine the shape (geometry) of PCl₃ and then decide on the appropriate hybridization of phosphorus in this molecule. (Phosphorus is the central atom.)
	A) sp³ B) sp² C) sp D) sp³d E) sp³d²
	Ans: A Difficulty: Difficult

86.	The number of pi bonds in the molecule below is
	A) 1 B) 2 C) 3 D) 5 E) 9
	Ans: C Difficulty: Medium

87.	The number of pi bonds in the molecule below is
	A) 2 B) 4 C) 6 D) 10 E) 15
	Ans: B Difficulty: Medium

88.	According to valence bond theory, the triple bond in ethyne (acetylene, C₂H₂) consists of
	A)	three s bonds and no p bonds.	D)	no s bonds and three p bonds.
	B)	two s bonds and one p bond.	E)	none of these choices is correct
	C)	one s bond and two p bonds.
	Ans: C Difficulty: Medium

89.	The number of pi bonds in the oxalate ion (C₂O₄^2–) is
	A) 1 B) 2 C) 3 D) 4 E) 5
	Ans: B Difficulty: Difficult

90.	Consider the species Cl₂⁺, Cl₂, and Cl₂^–. Which of these species will be paramagnetic?
	A)	Only Cl₂	D)	Cl₂⁺ and Cl₂^–
	B)	Cl₂⁺ and Cl₂	E)	All three are paramagnetic
	C)	Cl₂ and Cl₂^–
	Ans: D Difficulty: Medium

91.	Consider the species N₂^–, N₂, and N₂⁺. Which of these species will be paramagnetic?
	A)	N₂ and N₂^–	D)	Only N₂^–
	B)	N₂⁺ and N₂	E)	None are paramagnetic
	C)	N₂⁺ and N₂^–
	Ans: C Difficulty: Medium

92.	Which of the following is not true of molecular orbitals?
	A)	The number of molecular orbitals formed is always equal to the number of atomic orbitals combined.
	B)	A molecular orbital can accommodate up to two electrons.
	C)	When electrons are added to orbitals of the same energy, the most stable arrangement is predicted by Hund’s rule.
	D)	Low-energy molecular orbitals fill before high-energy molecular orbitals fill.
	E)	For any substance, the number of electrons in molecular orbitals is equal to the sum of all the valence electrons on the bonding atoms.
	Ans: E Difficulty: Medium

93.	The electrons in the delocalized molecular orbitals of benzene (C₆H₆)
	A)	are confined between two adjacent bonding atoms.
	B)	are free to move around the six-membered ring.
	C)	form the electron pairs in the C–H bonds of the compound.
	D)	are unevenly distributed through the molecule.
	E)	are responsible for the fact that the bonds between three pairs of carbon atoms in the ring are longer and stronger than the bonds between the other three pairs of carbon atoms.
	Ans: B Difficulty: Medium

94.	According to molecular orbital (MO) theory, the twelve outermost electrons in the O₂ molecule are distributed as follows:
	A)	12 in bonding MOs, 0 in antibonding MOs.
	B)	10 in bonding MOs, 2 in antibonding MOs.
	C)	9 in bonding MOs, 3 in antibonding MOs.
	D)	8 in bonding MOs, 4 in antibonding MOs.
	E)	7 in bonding MOs, 5 in antibonding MOs.
	Ans: D Difficulty: Medium

95.	According to molecular orbital theory, what is the bond order in the O₂⁺ ion?
	A) 5.5 B) 5 C) 4 D) 2.5 E) 1.5
	Ans: D Difficulty: Medium

96.	The nitrosonium ion, NO⁺, forms a number of interesting complexes with nickel, cobalt, and iron. According to molecular orbital theory, which of the following statements about NO⁺ is correct?
	A)	NO⁺ has a bond order of 2 and is paramagnetic.
	B)	NO⁺ has a bond order of 2 and is diamagnetic.
	C)	NO⁺ has a bond order of 3 and is paramagnetic.
	D)	NO⁺ has a bond order of 3 and is diamagnetic.
	E)	None of these statements is correct.
	Ans: D Difficulty: Difficult

97.	The BrF₅ molecule has polar bonds and has a net dipole moment.
	Ans: True Difficulty: Medium

98.	Pi bonds are covalent bonds in which the electron density is concentrated above and below the plane of the nuclei of the bonding atoms.
	Ans: True Difficulty: Easy

99.	The number of lone pairs of electrons on the central atoms is the main factor that is used to determine the molecular shape or molecular geometry.
	Ans: True Difficulty: Easy

100.	According to VSEPR theory, a molecule with the general formula AX₃E₂ (where E represents a lone pair on A) will be trigonal planar.
	Ans: False Difficulty: Medium

101.	A molecule which contains polar bonds will always have a dipole moment.
	Ans: False Difficulty: Medium

102.	To make a sp³ hybrid orbital, one s orbital is mixed with 3 p orbitals.
	Ans: True Difficulty: Easy

103.	The bond angle for a sp hybrid orbital is smaller than the bond angle for a sp² hybrid orbital.
	Ans: False Difficulty: Medium

104.	The angles between sp² hybrid orbitals are 109.5°.
	Ans: False Difficulty: Medium

105.	Atoms of period 3 and beyond can undergo sp³d ² hybridization, but atoms of period 2 cannot.
	Ans: True Difficulty: Medium

106.	In the valence bond treatment, overlap of an s orbital on one atom with an sp³ orbital on another atom can give rise to a s bond.
	Ans: True Difficulty: Medium

107.	In the valence bond treatment, a p bond is formed when two 2p orbitals overlap side to side
	Ans: True Difficulty: Easy

108.	According to molecular orbital theory, all diatomic molecules with an even number of electrons will be diamagnetic.
	Ans: False Difficulty: Medium

109.	To correctly determine the molecular shape of a molecule requires that you first draw the Lewis structure for the molecule.
	Ans: True Difficulty: Easy

110.	Use VSEPR theory to predict the molecular geometry of H₃O⁺ (hydronium ion).
	Ans:	trigonal pyramidal
	Difficulty: Medium

111.	Use VSEPR theory to predict the molecular geometry of CO₃^2–
	Ans:	trigonal planar
	Difficulty: Medium

112.	The N – N – H bond angles in hydrazine N₂H₄ are 112°. What is the hybridization of the nitrogen orbitals predicted by valence bond theory?
	Ans:	sp³.
	Difficulty: Medium

113.	How many p-bonds in CH₃COCH₃?
	Ans:	one.
	Difficulty: Medium

114.	According to the VSEPR theory, will the molecule PF₅ be polar or nonpolar?
	Ans:	nonpolar
	Difficulty: Medium

115.	How many electron domains are on the central atom for a sp² hybridized atom?
	Ans:	3
	Difficulty: Medium

116.	How many electron domains are on the central atom for a sp³d hybridized atom?
	Ans:	5
	Difficulty: Medium

117.	What name is given to the shape of a molecule with no lone pairs of electrons on the central atom and 6 electron domains on the central atom?
	Ans:	Octahedral
	Difficulty: Easy

118.	The total number of electron domains is used to determine the ___________.
	Ans:	Electron-Domain Geometry
	Difficulty: Easy

119.	The number of lone pairs on the central atoms is used to determine the ____________.
	Ans:	Molecular Geometry
	Difficulty: Easy

120.

Complete the following table.

Hybrid type	Geometry of electron pairs
a __________	linear
b sp³	__________
c __________	trigonal bipyramidal
d __________	octahedral
e sp²	__________

Ans:

Hybrid type	Geometry of electron pairs
a sp	linear
b sp³	tetrahedral
c sp³d	trigonal bipyramidal
d sp³d²	octahedral
e sp²	trigonal planar

Difficulty: Medium

121.	___________ _________ results from parallel overlap of two p orbitals.
	Ans:	p-bonds
	Difficulty: Easy

122.	Water has ___________ number of lone pairs of electrons on the central oxygen.
	Ans:	two
	Difficulty: Easy

123.	___________ is the electron-domain geometry and _________ is the molecular shape for ammonia.
	Ans:	tetrahedral and pyramidal
	Difficulty: Medium

124.	The bond angle for the carbonate ion is ___________.
	Ans:	120⁰
	Difficulty: Medium

125.	Draw a Lewis structure for PF₅ that shows the correct atom arrangement predicted by the VSEPR theory.
	Ans:
	Difficulty: Medium

126.

The Lewis structure of formaldehyde, CH₂O, is shown. Use VSEPR theory to predict the molecular geometry and the H–C–H bond angle. Outline your reasoning.

Ans:

There are three electron groups around the central atom, carbon. These are a double bond and two single bonds. The molecule is thus of the AX₃ type, and its geometry will be trigonal planar. The bond angles will be 120°.

Difficulty: Medium

127.	Draw the Lewis structure of XeF₄. Use this structure, in conjunction with VSEPR theory, to predict the shape of this molecule. Outline your reasoning.
	Ans:	The Lewis structure is shown alongside. The VSEPR formula is AX₄E₂, and the electron group arrangement is therefore octahedral. The lone pairs will lie at opposite vertices, resulting in a square planar molecular geometry.
	Difficulty: Difficult

128.	In one sentence state the basic principle of valence bond theory.
	Ans:	A covalent bond forms when the orbitals of two atoms overlap and a pair of electrons occupies the region between the nuclei.
	Difficulty: Easy

129.	In not more than two sentences, explain when and why chemists make use of the concept of hybridization.
	Ans:	Chemists postulate hybridization when the observed geometry of a molecule cannot be rationalized in terms of overlap of the s, p and/or d orbitals of the atoms concerned.
	Difficulty: Medium

130.	In one sentence state how molecular orbitals are usually obtained.
	Ans:	By the linear combination (addition or subtraction) of atomic orbitals.
	Difficulty: Medium

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Sample Chapter
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Sample Chapter

1.	The Lewis dot symbol consists of the symbol for the element surrounded by dot(s). What does the symbol represent?
	A)	Electron configuration	D)	Atomic mass
	B)	Valence electrons	E)	Nucleus and core electrons
	C)	Atomic number
	Ans: E Difficulty: Easy

2.	The Lewis dot symbol consists of the symbol for the element surrounded by dot(s). What does the dot or dots represent?
	A)	Electron configuration	D)	Atomic mass
	B)	Valence electrons	E)	Core electrons
	C)	Atomic number
	Ans: B Difficulty: Easy

3.	Which of the following contains ionic bonding?
	A) CO B) SrF₂ C) Al D) OCl₂ E) HCl
	Ans: B Difficulty: Easy

4.	How many electrons are in a single bond?
	A) 0 B) 1 C) 2 D) 4 E) 6
	Ans: C Difficulty: Easy

5.	How many electrons are in a double bond?
	A) 0 B) 1 C) 2 D) 4 E) 6
	Ans: D Difficulty: Easy

6.	How many electrons are in a triple bond?
	A) 0 B) 1 C) 2 D) 4 E) 6
	Ans: E Difficulty: Easy

7.	Arrange the following bonds in order of increasing bond strength.
	A)	C–I < C–Br < C–Cl < C–F	D)	C–I < C–Br < C–F< C–Cl
	B)	C–F < C–Cl < C–Br < C–I	E)	none of these orders is correct
	C)	C–Br < C–I < C–Cl < C–F
	Ans: A Difficulty: Medium

8.	Select the strongest bond in the following group.
	A) C–S B) C–O C) C=C D) CºN E) C–F
	Ans: D Difficulty: Easy

9.	Select the strongest bond in the following group.
	A) C–C B) C–O C) C=C D) CºC E) C–F
	Ans: D Difficulty: Easy

10.	Which is the correct order for increasing bond strength? (1) CºC (2) C=C (3) C–C
	A)	(3) < (2) < (1)	D)	(1) < (3) < (2)
	B)	(3) < (1) < (2)	E)	(2) < (3) < (1)
	C)	(1) < (2) < (3)
	Ans: A Difficulty: Easy

11.	What types of elements undergo covalent bonding?
	A)	1 metal and noble gas	D)	2 Group IA elements
	B)	a nonmetal and a metal	E)	an actinide
	C)	2 nonmetals
	Ans: C Difficulty: Easy

12.	In which of these substances are the atoms held together by polar covalent bonding?
	A) SrCl₂ B) CsCl C) ClF D) TiF₂ E) S₈
	Ans: C Difficulty: Easy

13.	A polar covalent bond would form in which one of these pairs of atoms?
	A) Cl ¾ Cl B) Si ¾ Si C) Ca ¾ Cl D) Cr ¾ Br E) P ¾ Cl
	Ans: E Difficulty: Easy

14.	A nonpolar covalent bond (i.e., pure covalent) would form in which of these pairs of atoms?
	A) Na ¾ Cl B) H ¾ Cl C) Li ¾ Br D) Se ¾ Br E) Br ¾ Br
	Ans: E Difficulty: Easy

15.	Which of these covalent bonds is the most polar (i.e., highest percent ionic character)?
	A) Al ¾ I B) Si ¾ I C) Al ¾ Cl D) Si ¾ Cl E) Si ¾ P
	Ans: C Difficulty: Medium

16.	The covalent bond with the greatest polarity would form in which of these atom pairs?
	A) Br ¾ Br B) S ¾ O C) C ¾ P D) C ¾ O E) B ¾ O
	Ans: E Difficulty: Medium

17.	In which of these pairs of atoms would the bond be the least polar (i.e., lowest percent ionic character)?
	A) C ¾ Cl B) C ¾ C C) C ¾ H D) O ¾ C E) N ¾ C
	Ans: B Difficulty: Medium

18.	Which of these elements has the greatest electronegativity?
	A) Na B) As C) Ga D) Cs E) Sb
	Ans: B Difficulty: Medium

19.	Which of these atoms is the most electronegative?
	A) Li B) Cs C) P D) As E) Ge
	Ans: C Difficulty: Medium

20.	Which of these elements is the least electronegative?
	A) Sr B) V C) Ni D) P E) I
	Ans: A Difficulty: Medium

21.	Which of the following elements is the most electronegative?
	A) S B) Ru C) Si D) Te E) Cs
	Ans: A Difficulty: Medium

22.	Which of the following elements is the least electronegative?
	A) Si B) Se C) S D) Sc E) Sr
	Ans: E Difficulty: Medium

23.	Arrange aluminum, nitrogen, phosphorus and indium in order of increasing electronegativity.
	A)	Al < In < N < P	D)	In < P < Al < N
	B)	Al < In < P < N	E)	None of these orders is correct.
	C)	In < Al < P < N
	Ans: C Difficulty: Medium

24.	Arrange calcium, rubidium, sulfur, and arsenic in order of decreasing electronegativity.
	A)	S > As > Rb > Ca	D)	As > S > Ca > Rb
	B)	S > As > Ca > Rb	E)	None of these orders is correct.
	C)	As > S > Rb > Ca
	Ans: B Difficulty: Medium

25.	Based on electronegativity trends in the periodic table, predict which of the following compounds will have the greatest % ionic character in its bonds.
	A) H₂O B) LiI C) CaO D) RbF E) HCl
	Ans: D Difficulty: Medium

26.	What is the magnitude of the partial positive and partial negative charges in the HBr molecule? (1D = 3.36 ´ 10^–30 C m; 1e^– = 1.6022 ´ 10^–19 C; bond length HBr = 1.41 angstroms; Dipole Moment HBr = 0.82D)
	A)	–0.36 and +0.36	D)	–0.121 and +0.121
	B)	–0.14 and +0.14	E)	–2.73 and +2.73
	C)	–0.273 and +0.273
	Ans: D Difficulty: Medium

27.	What is the magnitude of the partial positive and partial negative charges in the HI molecule? (1D = 3.36 ´ 10^–30 C m; 1e^– = 1.6022 ´ 10^–19 C; bond length HI = 1.61 angstroms; Dipole Moment HI = 0.44 D)
	A)	–0.76 and +0.76	D)	–0.6 and +0.6
	B)	–0.057 and +0.057	E)	–0.911 and +0.911
	C)	–1.22 and +1.22
	Ans: B Difficulty: Medium

28.	The total number of bonding electrons in a molecule of formaldehyde (H₂CO) is
	A) 3 B) 4 C) 6 D) 8 E) 18
	Ans: D Difficulty: Medium

29.	The total number of lone pairs in NCl₃ is
	A) 6 B) 8 C) 9 D) 10 E) 13
	Ans: D Difficulty: Medium

30.	The Lewis structure for CS₂ is:
	A) B) C) D)
	Ans: C Difficulty: Medium

31.	The Lewis structure for a chlorate ion, ClO₃^–, should show ____ single bond(s), ____ double bond(s), and ____ lone pair(s).
	A) 2, 1, 10 B) 3, 0, 9 C) 2, 1, 8 D) 3, 0, 10 E) 2, 1, 9
	Ans: D Difficulty: Difficult

32.	Which of these Lewis structures is incorrect?
	A) a B) b C) c D) d E) e
	Ans: E Difficulty: Difficult

33.	Which of these choices is a correct Lewis structure for ozone, O₃?
	A) a B) b C) c D) d E) e
	Ans: D Difficulty: Medium

38.	The formal charge on the sulfur atom in the resonance structure of sulfur dioxide which has one single bond and one double bond is
	A) 0 B) +1 C) –1 D) +2 E) –2
	Ans: B Difficulty: Difficult

39.	What is the formal charge on phosphorus in a Lewis structure for the phosphate ion that satisfies the octet rule?
	A) –2 B) –1 C) 0 D) +1 E) +2
	Ans: D Difficulty: Difficult

40.	In the best Lewis structure for the fulminate ion, CNO^–, what is the formal charge on the central nitrogen atom?
	A) +2 B) +1 C) 0 D) –1 E) –2
	Ans: B Difficulty: Difficult

41.	In the Lewis structure of the iodate ion, IO₃^–, that satisfies the octet rule, the formal charge on the central iodine atom is
	A) +2 B) +1 C) 0 D) –1 E) –2
	Ans: A Difficulty: Difficult

46.	The number of resonance structures for the sulfur dioxide molecule that satisfy the octet rule is
	A) 1 B) 2 C) 3 D) 4 E) None of these
	Ans: B Difficulty: Difficult

47.	The number of resonance structures for the nitrate ion that satisfy the octet rule is
	A) 1 B) 2 C) 3 D) 4 E) None of these
	Ans: C Difficulty: Difficult

48.	In which one of the following is the best Lewis structure a resonance structure?
	A) SO₃ B) BF₃ C) I₃^– D) SCO (C = central atom) E) SO₃^2–
	Ans: A Difficulty: Difficult

49.	In which one of the following species is the central atom (the first atom in the formula) likely to violate the octet rule?
	A) BF₄^– B) XeO₃ C) SiCl₄ D) NH₃ E) CH₂Cl₂
	Ans: B Difficulty: Difficult

50.	Which of the following atoms can expand its valence shell when bonding?
	A) N B) C C) O D) P E) Al
	Ans: D Difficulty: Medium

51.	Which of these substances will display an incomplete octet in its Lewis structure?
	A) CO₂ B) Cl₂ C) ICl D) NO E) SO₂
	Ans: D Difficulty: Medium

52.	Which of these elements is most likely to exhibit an expanded octet in its compounds?
	A) O B) S C) Na D) C E) N
	Ans: B Difficulty: Medium

53.	Which response includes all the molecules below that do not follow the octet rule? (1) H₂S (2) BCl₃ (3) PH₃ (4) SF₄
	A) (2) and (4) B) (2) and (3) C) (1) and (2) D) (3) and (4) E) (1) and (4)
	Ans: A Difficulty: Difficult

54.	Which of these molecules has an atom with an expanded octet?
	A) HCl B) AsCl₅ C) ICl D) NCl₃ E) Cl₂
	Ans: B Difficulty: Medium

55.	Which molecule has a Lewis structure that does not obey the octet rule?
	A) N₂O B) CS₂ C) PH₃ D) CCl₄ E) NO₂
	Ans: E Difficulty: Medium

56.	Ionic compounds tend to form between metals and nonmetals when electrons are transferred from an element with high ionization energy (metal) to an element with a low electron affinity (nonmetal).
	Ans: False Difficulty: Medium

57.	Lewis theorized the octet rule to describe chemical bonding where atoms lose, gain, or share electrons in order to achieve a noble gas configuration.
	Ans: True Difficulty: Easy

58.	Only valence electrons are shown in the Lewis structure held together by covalent bonds.
	Ans: True Difficulty: Easy

59.	A double bond can not exist between a carbon atom and an oxygen atom.
	Ans: False Difficulty: Easy

60.	A triple bond can not exist between a carbon atom and a hydrogen atom.
	Ans: True Difficulty: Easy

61.	Unshared electrons are always shown in pairs around an atom.
	Ans: False Difficulty: Easy

62.	The octet rule works best for elements in the 3^rd period of the periodic table.
	Ans: False Difficulty: Medium

63.	Multiple bonds are longer than single bonds.
	Ans: False Difficulty: Easy

64.	Single bonds are stronger than multiple bonds.
	Ans: False Difficulty: Easy

65.	What theory describes atoms losing, gaining, or sharing electrons to achieve a noble gas configuration?
	Ans:	octet rule
	Difficulty: Easy

66.	What is the distance between the nuclei of two covalently bonded atoms in a molecule?
	Ans:	bond length
	Difficulty: Easy

67.	What term describes the ability of an atom in a compound to pull the electrons to itself?
	Ans:	electronegativity
	Difficulty: Easy

68.	How many lone pairs of electrons are on the central atom in the Lewis structure for NH₃?
	Ans:	1
	Difficulty: Easy

69.	Give the equation for percent ionic character.
	Ans:	(observed dipole moment/calculated dipole moment assuming discrete charges) ´ 100%
	Difficulty: Medium

70.	Give the equation for formal charge.
	Ans:	# valence electrons – (1/2)(bonded electrons) – lone electrons
	Difficulty: Medium

71.	The number of dots in the Lewis dot symbol for a main group element is the same as the ___________ ___________.
	Ans:	group number
	Difficulty: Easy

72.	___________ ___________ of atoms interact to form compounds.
	Ans:	Valence electrons
	Difficulty: Easy

73.	In the Lewis dot symbol, the element symbol represents the ________ _________ and the dots represent the __________ ___________.
	Ans:	core electrons; valence electrons
	Difficulty: Easy

74.	A triple bond arises when two atoms share ___________ pairs of electrons.
	Ans:	three
	Difficulty: Easy

75.	A single bond between two atoms represents ________ pair(s) of electrons
	Ans:	one
	Difficulty: Easy

76.	______________ is a representation of covalent bonding in which shared electron pairs are shown either as dashes or as pairs of dots between two atoms and unshared electrons are shown as dots around the individual atoms.
	Ans:	Lewis structure
	Difficulty: Easy

77.	Using appropriate, real examples to illustrate your answer, describe the correlation between bond energy and bond length for a series of single bonds.
	Ans:	The bonds between carbon, C, and the halogens, X (X = F, Cl, Br, I) can be used as an examples. The size of X increases as one moves down the group. This means that the C–X bond length will become correspondingly longer. As this occurs the bond becomes weaker. Thus, the C–I bond is the longest and weakest, C–F the shortest and strongest of the series.
	Difficulty: Medium

78.	Using appropriate, real examples to illustrate your answer, describe the correlation between bond energy and bond length for a series of varying bond order.
	Ans:	Carbon and oxygen form single, double and triple bonds. The CºO bond in carbon monoxide is roughly three times as strong as the C–O single bond, while the C=O bond is about twice as strong as the single bond. The bond energy is approximately proportional to the bond order.
	Difficulty: Medium

79.	Describe in brief how electronegativity values can be used to predict the percent ionic character of a bond between two atoms.
	Ans:	Take the electronegativity difference (DEN) of the bonded atoms. The larger the difference between their electronegativities, the more ionic will be the nature of the bond. If DEN = 0, the bond will be pure covalent.
	Difficulty: Medium

1.	What does VSEPR model mean?
	A)	Very Specific Electron and Proton Repair model
	B)	Variable Selective of Electron and PRotons
	C)	Valence Shell for Every Proton
	D)	Very Selective Electron PaiR theory
	E)	Valence Shell Electron-Pair Repulsion
	Ans: E Difficulty: Easy

2.	Which of the following is required for determination of the VSEPR model and the molecular shape?
	A)	Atomic mass	D)	Lewis structure
	B)	# of protons	E)	None of the answers is correct
	C)	Oxidation number
	Ans: D Difficulty: Easy

3.	According to the VSEPR theory, the shape of the SO₃ molecule is
	A)	pyramidal.	D)	distorted tetrahedron (seesaw).
	B)	tetrahedral.	E)	square planar.
	C)	trigonal planar.
	Ans: C Difficulty: Medium

4.	What is the molecular shape of the CH₄ molecule?
	A)	tetrahedral.	D)	square planar.
	B)	trigonal pyramidal	E)	distorted tetrahedron (seesaw).
	C)	trigonal planar.
	Ans: A Difficulty: Easy

5.	Use VSEPR theory to predict the shape of the PCl₃ molecule.
	A) linear B) bent C) trigonal planar D) trigonal pyramidal E) tetrahedral
	Ans: D Difficulty: Medium

6.	What is the molecular shape of the H₂O molecule?
	A)	tetrahedral.	D)	square planar.
	B)	trigonal pyramidal	E)	distorted tetrahedron (seesaw).
	C)	bent.
	Ans: C Difficulty: Easy

7.	What is the molecular shape of the IBr₃ molecule?
	A)	tetrahedral.	D)	trigonal planar.
	B)	T-shaped	E)	distorted tetrahedron (seesaw).
	C)	bent.
	Ans: B Difficulty: Medium

8.	According to the VSEPR theory, the molecular shape of the carbonate ion, CO₃^{2 –}, is
	A)	square planar.	D)	trigonal planar.
	B)	tetrahedral.	E)	octahedral.
	C)	pyramidal.
	Ans: D Difficulty: Medium

9.	According to the VSEPR theory, the molecular shape of SiCl₄ is
	A) linear. B) trigonal planar. C) bent. D) tetrahedral. E) trigonal pyramidal.
	Ans: D Difficulty: Easy

10.	According to the VSEPR theory, the molecular shape of ammonia is
	A) linear. B) trigonal planar. C) bent. D) tetrahedral. E) trigonal pyramidal.
	Ans: E Difficulty: Medium

11.	According to the VSEPR theory, which one of the following species should be linear?
	A) H₂S B) HCN C) BF₃ D) H₂CO E) SO₃
	Ans: B Difficulty: Medium

12.	According to VSEPR theory, which one of the following molecules should have a shape that is trigonal bipyramidal?
	A) SF₄ B) XeF₄ C) NF₃ D) SF₆ E) PF₅
	Ans: E Difficulty: Medium

13.	Which one of the following molecules has tetrahedral geometry?
	A) XeF₄ B) BF₃ C) AsF₅ D) CF₄ E) NH₃
	Ans: D Difficulty: Medium

14.	Predict the geometry around the central atom in PO₄^3–.
	A)	trigonal planar.	D)	trigonal bipyramidal.
	B)	trigonal pyramidal.	E)	octahedral.
	C)	tetrahedral.
	Ans: C Difficulty: Medium

15.	Predict the geometry around the central atom in SO₃^2–.
	A)	trigonal planar.	D)	trigonal bipyramidal.
	B)	trigonal pyramidal.	E)	octahedral.
	C)	tetrahedral.
	Ans: B Difficulty: Medium

16.	What is the total number of electron domains for a molecule having a trigonal pyramidal molecular geometry such as NH₃?
	A) 5 B) 2 C) 3 D) 4 E) 6
	Ans: D Difficulty: Medium

17.	What is the total number of electron domains for a molecule having a T-shaped pyramidal molecular geometry such as BrF₃?
	A) 5 B) 2 C) 3 D) 4 E) 6
	Ans: A Difficulty: Medium

18.	What is the total number of electron domains for a molecule having a square pyramidal molecular geometry such as ClF₅?
	A) 5 B) 2 C) 3 D) 4 E) 6
	Ans: E Difficulty: Medium

19.	What is the total number of electron domains for a molecule having a square planar molecular geometry such as XeBr₄?
	A) 5 B) 2 C) 3 D) 4 E) 6
	Ans: E Difficulty: Medium

20.	What is the number of lone electron pairs on the central atom of a molecule having a molecular geometry of seesaw-shaped such as SF₄?
	A) 1 B) 2 C) 3 D) 4 E) 6
	Ans: A Difficulty: Medium

21.	What is the number of lone electron pairs on the central atom of a molecule having a trigonal pyramidal molecular geometry such as NH₃?
	A) 1 B) 2 C) 3 D) 0 E) 4
	Ans: A Difficulty: Medium

22.	What is the number of lone electron pairs on the central atom of a molecule having a linear molecular geometry such as CO₂?
	A) 1 B) 2 C) 3 D) 0 E) 4
	Ans: D Difficulty: Medium

23.	What is the number of lone electron pairs on the central atom of a molecule having a linear molecular geometry such as ClF₂^–?
	A) 1 B) 2 C) 3 D) 0 E) 4
	Ans: C Difficulty: Medium

24.	According to VSEPR theory, a molecule with the general formula AX₃E_o will have a ______ molecular shape.
	A) linear. B) bent. C) trigonal planar. D) tetrahedral. E) trigonal pyramidal.
	Ans: C Difficulty: Medium

25.	According to VSEPR theory, a molecule with the general formula AX₅E_o will have a ______ molecular shape.
	A)	tetrahedral.	D)	trigonal bipyramidal.
	B)	trigonal planar.	E)	see-saw.
	C)	trigonal pyramidal.
	Ans: D Difficulty: Medium

26.	According to VSEPR theory, a molecule with the general formula AX₂E₂ will have a _____ molecular shape.
	A) linear. B) bent. C) trigonal planar. D) tetrahedral. E) see-saw.
	Ans: B Difficulty: Medium

27.	According to VSEPR theory, a molecule with the general formula AX₄E₂ will have a _____ molecular shape.
	A)	tetrahedral.	D)	octahedral.
	B)	square pyramidal.	E)	see-saw.
	C)	square planar.
	Ans: C Difficulty: Medium

28.	According to VSEPR theory, a molecule with the general formula AX₅E will have a ______ molecular shape.
	A)	tetrahedral.	D)	octahedral.
	B)	trigonal bipyramidal	E)	see-saw.
	C)	square pyramidal
	Ans: C Difficulty: Medium

30.	What is the molecular shape of the thiocyanate anion, SCN^–, as predicted by the VSEPR theory? (Carbon is the central atom.)
	A) linear B) bent C) angular D) trigonal E) none of these choices is correct
	Ans: A Difficulty: Medium

31.	What is the molecular shape of BeH₂ as predicted by the VSEPR theory?
	A) linear B) bent C) angular D) trigonal E) none of these choices is correct
	Ans: A Difficulty: Medium

33.	What is the molecular shape of NO₂^– as predicted by the VSEPR theory?
	A) linear B) trigonal planar C) bent D) tetrahedral E) resonant
	Ans: C Difficulty: Medium

34.	What is the molecular shape of ClO₃F as predicted by the VSEPR theory?
	A)	trigonal pyramidal	D)	tetrahedral
	B)	square planar	E)	octahedral
	C)	square pyramidal
	Ans: D Difficulty: Medium

35.	What is the molecular shape of HOF as predicted by the VSEPR theory?
	A) trigonal pyramidal B) trigonal C) tetrahedral D) linear E) bent
	Ans: E Difficulty: Medium

36.	What is the molecular shape of XeO₂F₂ as predicted by the VSEPR theory?
	A)	square planar	D)	see-saw
	B)	tetrahedral	E)	octahedral
	C)	square pyramidal
	Ans: D Difficulty: Medium

37.	What is the molecular shape of ClF₂^– as predicted by the VSEPR theory?
	A) linear B) bent C) see-saw D) T-shaped E) L-shaped
	Ans: A Difficulty: Medium

38.	What is the molecular shape of SiF₆^2– as predicted by the VSEPR theory?
	A)	trigonal bipyramidal	D)	see-saw
	B)	hexagonal	E)	octahedral
	C)	tetrahedral
	Ans: E Difficulty: Medium

39.	Use VSEPR theory to predict the electron group arrangement around iodine, the central atom in the ion IF₂^–.
	A)	octahedral	D)	trigonal planar
	B)	trigonal bipyramidal	E)	bent
	C)	tetrahedral
	Ans: B Difficulty: Medium

40.	Use VSEPR theory to decide which one of the following molecules and ions will definitely have at least one 90° bond angle in it. (In each case except water, the central atom is the first one in the formula.)
	A) AlCl₄^– B) NH₃ C) PCl₅ D) CO₂ E) H₂O
	Ans: C Difficulty: Medium

41.	What is the approximate bond angle for CCl₄?
	A) 90° B) 109.5° C) 120° D) 145° E) 180°
	Ans: B Difficulty: Easy

42.	The F – S – F bond angles in SF₆ are
	A) 90° and 180° B) 109.5° C) 120° D) 180° E) 90° and 120°
	Ans: A Difficulty: Medium

43.	What is the approximate bond angle for NH₃?
	A) 90° B) 109.5° C) 120° D) 107° E) 105°
	Ans: D Difficulty: Medium

44.	What is the approximate bond angle for CO₂?
	A) 90° B) 109.5° C) 120° D) 107° E) 180°
	Ans: E Difficulty: Medium

45.	What is the approximate bond angle for H₂O?
	A) 90° B) 109.5° C) 120° D) 107° E) 105°
	Ans: E Difficulty: Medium

46.	Predict the ideal bond angles in AsCl₃ using the molecular shape given by the VSEPR theory.
	A) 90° B) 109° C) 120° D) 180° E) between 110 and 120°
	Ans: B Difficulty: Medium

47.	Predict the actual bond angles in BrF₃ using the VSEPR theory.
	A)	more than 120°	D)	between 90° and 109°
	B)	exactly 120°	E)	less than 90°
	C)	between 109° and 120°
	Ans: E Difficulty: Medium

48.	What is the approximate bond angle for CH₄?
	A) 90° B) 109.5° C) 120° D) 107° E) 105°
	Ans: B Difficulty: Easy

49.	How do you describe the molecular geometry of a molecule that does not have a central atom?
	A)	Describe the molecular geometry around the most electronegative atom.
	B)	Describe the molecular geometry around all non-hydrogen atoms.
	C)	Describe the molecular geometry around the most electropositive atom.
	D)	Describe the molecular geometry around the atom with the largest atomic radius.
	E)	Describe the molecular geometry around the atom with the largest bond angle.
	Ans: B Difficulty: Medium

50.	Which one of the following molecules is nonpolar?
	A) NH₃ B) OF₂ C) CH₃Cl D) H₂O E) BeCl₂
	Ans: E Difficulty: Difficult

51.	Complete this sentence: The PCl₅ molecule has
	A)	nonpolar bonds, and is a nonpolar molecule.
	B)	nonpolar bonds, but is a polar molecule.
	C)	polar bonds, and is a polar molecule.
	D)	polar bonds, but is a nonpolar molecule.
	Ans: D Difficulty: Difficult

52.	Which one of the following molecules is nonpolar?
	A) CO₂ B) BF₃ C) KCl D) IBr₃ E) CHCl₃
	Ans: A Difficulty: Difficult

53.	Which one of the following molecules has a zero dipole moment?
	A) CO B) CH₂Cl₂ C) SO₃ D) SO₂ E) NH₃
	Ans: C Difficulty: Difficult

54.	What is the dipole moment for CO₂?
	A)	–1	D)	need more information
	B)	0	E)	None of the answers is correct
	C)	+1
	Ans: B Difficulty: Medium

55.	Which one of the following molecules is polar?
	A) PBr₅ B) CCl₄ C) BrF₅ D) XeF₂ E) XeF₄
	Ans: C Difficulty: Difficult

56.	Predict the molecular geometry and polarity of the SO₂ molecule.
	A)	linear, polar	D)	bent, nonpolar
	B)	linear, nonpolar	E)	None of the above.
	C)	bent, polar
	Ans: C Difficulty: Difficult

57.	Predict the geometry and polarity of the CS₂ molecule.
	A)	linear, polar	D)	bent, nonpolar
	B)	linear, nonpolar	E)	bent, polar
	C)	tetrahedral, nonpolar
	Ans: B Difficulty: Difficult

58.	Which one of the following molecules is polar?
	A) CH₄ B) CHBr₃ C) F₂ D) CBr₄ E) CO₂
	Ans: B Difficulty: Difficult

59.	Which of the following molecules has a net dipole moment?
	A) BeCl₂ B) SF₂ C) KrF₂ D) CO₂ E) CCl₄
	Ans: B Difficulty: Difficult

60.	Which of the following has no net dipole moment?
	A) N₂O B) NF₃ C) H₂Se D) TeO₃ E) CH₃Cl
	Ans: D Difficulty: Difficult

61.	Which of the following atoms, in the ground state, has unpaired electrons?
	A) Ca B) Ne C) Mg D) He E) C
	Ans: E Difficulty: Easy

62.	Which of the following atoms, in the ground state, does not have unpaired electrons?
	A) P B) Na C) Ne D) C E) S
	Ans: C Difficulty: Easy

63.	How many bonds should an oxygen atom form?
	A) 1 B) 2 C) 3 D) 6 E) 4
	Ans: B Difficulty: Easy

64.	How many bonds should a carbon atom form?
	A) 1 B) 2 C) 3 D) 6 E) 4
	Ans: E Difficulty: Easy

65.	How many bonds should a fluorine atom form?
	A) 1 B) 2 C) 3 D) 6 E) 4
	Ans: A Difficulty: Easy

66.	Indicate the type of hybrid orbitals used by the central atom in PCl₃.
	A) sp B) sp² C) sp³ D) sp³d E) sp³d²
	Ans: C Difficulty: Difficult

67.	Indicate the type of hybrid orbitals used by the central atom in CCl₄.
	A) sp B) sp² C) sp³ D) sp³d E) sp³d²
	Ans: D Difficulty: Medium

68.	Indicate the type of hybrid orbitals used by the central atom in SF₆.
	A) sp B) sp² C) sp³ D) sp³d E) sp³d²
	Ans: E Difficulty: Medium

69.	What is the hybridization of the As atom in the AsF₅ molecule?
	A) sp B) sp² C) sp³ D) sp³d E) sp³d²
	Ans: D Difficulty: Medium

70.	What is the hybridization on the central atom in NO₃^–?
	A) sp B) sp² C) sp³ D) sp³d E) sp³d²
	Ans: B Difficulty: Difficult

71.	In which one of the following molecules is the central atom sp² hybridized?
	A) SO₂ B) N₂O C) BeCl₂ D) NF₃ E) PF₅
	Ans: A Difficulty: Difficult

72.	What is the hybridization of As in the AsF₄^– ion?
	A) sp B) sp² C) sp³ D) sp³d E) sp³d²
	Ans: D Difficulty: Difficult

73.	What is the hybridization of the central atom in ClO₃^–?
	A) sp B) sp² C) sp³ D) sp³d E) sp³d²
	Ans: C Difficulty: Difficult

74.	The hybridization of the central nitrogen atom in the molecule N₂O is
	A) sp B) sp² C) sp³ D) sp³d E) sp³d²
	Ans: A Difficulty: Difficult

75.	A molecule with the formula AX₂ uses _________ to form its bonds.
	A)	sp hybrid orbitals	D)	sp³d hybrid orbitals
	B)	sp² hybrid orbitals	E)	sp³d² hybrid orbitals
	C)	sp³ hybrid orbitals
	Ans: A Difficulty: Difficult

76.	A molecule with the formula AX₄ uses _________ to form its bonds.
	A)	sp hybrid orbitals	D)	sp³d hybrid orbitals
	B)	sp² hybrid orbitals	E)	sp³d² hybrid orbitals
	C)	sp³ hybrid orbitals
	Ans: C Difficulty: Difficult

77.	A molecule with the formula AX₄E₂ uses _________ to form its bonds.
	A)	sp hybrid orbitals	D)	sp³d hybrid orbitals
	B)	sp² hybrid orbitals	E)	sp³d² hybrid orbitals
	C)	sp³ hybrid orbitals
	Ans: E Difficulty: Difficult

78.	Carbon uses ______ hybrid orbitals in ClCN.
	A) sp B) sp² C) sp³ D) sp³d E) sp³d²
	Ans: A Difficulty: Difficult

79.	Valence bond theory predicts that carbon will use _____ hybrid orbitals in the carbonate anion, CO₃^2–.
	A) sp B) sp² C) sp³ D) sp³d E) sp³d²
	Ans: B Difficulty: Difficult

80.	Valence bond theory predicts that sulfur will use _____ hybrid orbitals in sulfur dioxide, SO₂.
	A) sp B) sp² C) sp³ D) sp³d E) sp³d²
	Ans: B Difficulty: Difficult

81.	When PCl₅ solidifies it forms PCl₄⁺ cations and PCl₆^–anions. According to valence bond theory, what hybrid orbitals are used by phosphorus in the PCl₄⁺ cations?
	A) sp B) sp² C) sp³ D) sp³d E) sp³d²
	Ans: C Difficulty: Difficult

82.	Valence bond theory predicts that iodine will use _____ hybrid orbitals in ICl₂^–.
	A) sp² B) sp³ C) sp³d D) sp³d² E) none of these choices is correct
	Ans: C Difficulty: Difficult

83.	Which one of the following statements about orbital hybridization is incorrect?
	A)	The carbon atom in CH₄ is sp³ hybridized.
	B)	The carbon atom in CO₂ is sp hybridized.
	C)	The nitrogen atom in NH₃ is sp² hybridized.
	D)	sp² hybrid orbitals are coplanar, and at 120° to each other.
	E)	sp hybrid orbitals lie at 180° to each other.
	Ans: C Difficulty: Difficult

84.	For which one of the following molecules is the indicated type of hybridization not appropriate for the central atom?
	A)	BeCl₂sp²	D)	C₂H₂sp
	B)	SiH₄sp³	E)	H₂O sp³
	C)	BF₃sp²
	Ans: A Difficulty: Difficult

85.	Determine the shape (geometry) of PCl₃ and then decide on the appropriate hybridization of phosphorus in this molecule. (Phosphorus is the central atom.)
	A) sp³ B) sp² C) sp D) sp³d E) sp³d²
	Ans: A Difficulty: Difficult

86.	The number of pi bonds in the molecule below is
	A) 1 B) 2 C) 3 D) 5 E) 9
	Ans: C Difficulty: Medium

87.	The number of pi bonds in the molecule below is
	A) 2 B) 4 C) 6 D) 10 E) 15
	Ans: B Difficulty: Medium

88.	According to valence bond theory, the triple bond in ethyne (acetylene, C₂H₂) consists of
	A)	three s bonds and no p bonds.	D)	no s bonds and three p bonds.
	B)	two s bonds and one p bond.	E)	none of these choices is correct
	C)	one s bond and two p bonds.
	Ans: C Difficulty: Medium

89.	The number of pi bonds in the oxalate ion (C₂O₄^2–) is
	A) 1 B) 2 C) 3 D) 4 E) 5
	Ans: B Difficulty: Difficult

90.	Consider the species Cl₂⁺, Cl₂, and Cl₂^–. Which of these species will be paramagnetic?
	A)	Only Cl₂	D)	Cl₂⁺ and Cl₂^–
	B)	Cl₂⁺ and Cl₂	E)	All three are paramagnetic
	C)	Cl₂ and Cl₂^–
	Ans: D Difficulty: Medium

91.	Consider the species N₂^–, N₂, and N₂⁺. Which of these species will be paramagnetic?
	A)	N₂ and N₂^–	D)	Only N₂^–
	B)	N₂⁺ and N₂	E)	None are paramagnetic
	C)	N₂⁺ and N₂^–
	Ans: C Difficulty: Medium

92.	Which of the following is not true of molecular orbitals?
	A)	The number of molecular orbitals formed is always equal to the number of atomic orbitals combined.
	B)	A molecular orbital can accommodate up to two electrons.
	C)	When electrons are added to orbitals of the same energy, the most stable arrangement is predicted by Hund’s rule.
	D)	Low-energy molecular orbitals fill before high-energy molecular orbitals fill.
	E)	For any substance, the number of electrons in molecular orbitals is equal to the sum of all the valence electrons on the bonding atoms.
	Ans: E Difficulty: Medium

93.	The electrons in the delocalized molecular orbitals of benzene (C₆H₆)
	A)	are confined between two adjacent bonding atoms.
	B)	are free to move around the six-membered ring.
	C)	form the electron pairs in the C–H bonds of the compound.
	D)	are unevenly distributed through the molecule.
	E)	are responsible for the fact that the bonds between three pairs of carbon atoms in the ring are longer and stronger than the bonds between the other three pairs of carbon atoms.
	Ans: B Difficulty: Medium

94.	According to molecular orbital (MO) theory, the twelve outermost electrons in the O₂ molecule are distributed as follows:
	A)	12 in bonding MOs, 0 in antibonding MOs.
	B)	10 in bonding MOs, 2 in antibonding MOs.
	C)	9 in bonding MOs, 3 in antibonding MOs.
	D)	8 in bonding MOs, 4 in antibonding MOs.
	E)	7 in bonding MOs, 5 in antibonding MOs.
	Ans: D Difficulty: Medium

95.	According to molecular orbital theory, what is the bond order in the O₂⁺ ion?
	A) 5.5 B) 5 C) 4 D) 2.5 E) 1.5
	Ans: D Difficulty: Medium

96.	The nitrosonium ion, NO⁺, forms a number of interesting complexes with nickel, cobalt, and iron. According to molecular orbital theory, which of the following statements about NO⁺ is correct?
	A)	NO⁺ has a bond order of 2 and is paramagnetic.
	B)	NO⁺ has a bond order of 2 and is diamagnetic.
	C)	NO⁺ has a bond order of 3 and is paramagnetic.
	D)	NO⁺ has a bond order of 3 and is diamagnetic.
	E)	None of these statements is correct.
	Ans: D Difficulty: Difficult

97.	The BrF₅ molecule has polar bonds and has a net dipole moment.
	Ans: True Difficulty: Medium

98.	Pi bonds are covalent bonds in which the electron density is concentrated above and below the plane of the nuclei of the bonding atoms.
	Ans: True Difficulty: Easy

99.	The number of lone pairs of electrons on the central atoms is the main factor that is used to determine the molecular shape or molecular geometry.
	Ans: True Difficulty: Easy

100.	According to VSEPR theory, a molecule with the general formula AX₃E₂ (where E represents a lone pair on A) will be trigonal planar.
	Ans: False Difficulty: Medium

101.	A molecule which contains polar bonds will always have a dipole moment.
	Ans: False Difficulty: Medium

102.	To make a sp³ hybrid orbital, one s orbital is mixed with 3 p orbitals.
	Ans: True Difficulty: Easy

103.	The bond angle for a sp hybrid orbital is smaller than the bond angle for a sp² hybrid orbital.
	Ans: False Difficulty: Medium

104.	The angles between sp² hybrid orbitals are 109.5°.
	Ans: False Difficulty: Medium

105.	Atoms of period 3 and beyond can undergo sp³d ² hybridization, but atoms of period 2 cannot.
	Ans: True Difficulty: Medium

106.	In the valence bond treatment, overlap of an s orbital on one atom with an sp³ orbital on another atom can give rise to a s bond.
	Ans: True Difficulty: Medium

107.	In the valence bond treatment, a p bond is formed when two 2p orbitals overlap side to side
	Ans: True Difficulty: Easy

108.	According to molecular orbital theory, all diatomic molecules with an even number of electrons will be diamagnetic.
	Ans: False Difficulty: Medium

109.	To correctly determine the molecular shape of a molecule requires that you first draw the Lewis structure for the molecule.
	Ans: True Difficulty: Easy

110.	Use VSEPR theory to predict the molecular geometry of H₃O⁺ (hydronium ion).
	Ans:	trigonal pyramidal
	Difficulty: Medium

111.	Use VSEPR theory to predict the molecular geometry of CO₃^2–
	Ans:	trigonal planar
	Difficulty: Medium

112.	The N – N – H bond angles in hydrazine N₂H₄ are 112°. What is the hybridization of the nitrogen orbitals predicted by valence bond theory?
	Ans:	sp³.
	Difficulty: Medium

113.	How many p-bonds in CH₃COCH₃?
	Ans:	one.
	Difficulty: Medium

114.	According to the VSEPR theory, will the molecule PF₅ be polar or nonpolar?
	Ans:	nonpolar
	Difficulty: Medium

115.	How many electron domains are on the central atom for a sp² hybridized atom?
	Ans:	3
	Difficulty: Medium

116.	How many electron domains are on the central atom for a sp³d hybridized atom?
	Ans:	5
	Difficulty: Medium

117.	What name is given to the shape of a molecule with no lone pairs of electrons on the central atom and 6 electron domains on the central atom?
	Ans:	Octahedral
	Difficulty: Easy

118.	The total number of electron domains is used to determine the ___________.
	Ans:	Electron-Domain Geometry
	Difficulty: Easy

119.	The number of lone pairs on the central atoms is used to determine the ____________.
	Ans:	Molecular Geometry
	Difficulty: Easy

Hybrid type	Geometry of electron pairs
a __________	linear
b sp³	__________
c __________	trigonal bipyramidal
d __________	octahedral
e sp²	__________

Hybrid type	Geometry of electron pairs
a sp	linear
b sp³	tetrahedral
c sp³d	trigonal bipyramidal
d sp³d²	octahedral
e sp²	trigonal planar

121.	___________ _________ results from parallel overlap of two p orbitals.
	Ans:	p-bonds
	Difficulty: Easy

122.	Water has ___________ number of lone pairs of electrons on the central oxygen.
	Ans:	two
	Difficulty: Easy

123.	___________ is the electron-domain geometry and _________ is the molecular shape for ammonia.
	Ans:	tetrahedral and pyramidal
	Difficulty: Medium

124.	The bond angle for the carbonate ion is ___________.
	Ans:	120⁰
	Difficulty: Medium

125.	Draw a Lewis structure for PF₅ that shows the correct atom arrangement predicted by the VSEPR theory.
	Ans:
	Difficulty: Medium

127.	Draw the Lewis structure of XeF₄. Use this structure, in conjunction with VSEPR theory, to predict the shape of this molecule. Outline your reasoning.
	Ans:	The Lewis structure is shown alongside. The VSEPR formula is AX₄E₂, and the electron group arrangement is therefore octahedral. The lone pairs will lie at opposite vertices, resulting in a square planar molecular geometry.
	Difficulty: Difficult

128.	In one sentence state the basic principle of valence bond theory.
	Ans:	A covalent bond forms when the orbitals of two atoms overlap and a pair of electrons occupies the region between the nuclei.
	Difficulty: Easy

129.	In not more than two sentences, explain when and why chemists make use of the concept of hybridization.
	Ans:	Chemists postulate hybridization when the observed geometry of a molecule cannot be rationalized in terms of overlap of the s, p and/or d orbitals of the atoms concerned.
	Difficulty: Medium

130.	In one sentence state how molecular orbitals are usually obtained.
	Ans:	By the linear combination (addition or subtraction) of atomic orbitals.
	Difficulty: Medium

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Test bank for Chemistry Atoms First 1st Edition Burdge Overby

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