Chapter 9 1 Use Lewis theory to determine the chemical formula

Chemistry: A Molecular Approach, 2e (Tro)

Chapter 9 Chemical Bonding I: Lewis Theory

Multiple Choice Questions

1) Which of the following statements is TRUE?

A) A covalent bond is formed through the transfer of electrons from one atom to another.

B) A pair of electrons involved in a covalent bond are sometimes referred to as “lone pairs.”

C) It is not possible for two atoms to share more than two electrons.

D) Single bonds are shorter than double bonds.

E) A covalent bond has a lower potential energy than the two separate atoms.

2) Which of the following represent the Lewis structure for N?

A)

B)

C)

D)

E)

3) Which of the following represent the Lewis structure for Cl?

A)

B)

C)

D)

E)

4) Which of the following represent the Lewis structure for Mg?

A)

B)

C)

D)

E)

2

5) Which of the following represent the Lewis structure for Br⁻?

A)

B)

C)

D)

E)

6) Which of the following represent the Lewis structure for Ca2⁺?

A)

B)

C)

D)

E)

7) Which of the following represent the Lewis structure for S2⁻?

A)

B)

C)

D)

E)

8) Give the complete electronic configuration for Br–.

A) 1s22s22p63s23p64s24p6

B) 1s22s22p63s23p64s24d104p6

C) 1s22s22p63s23p64s23d104p6

D) 1s22s22p63s23p64s23d104p5

E) 1s22s2p63s2p64s23d104p6

9) Give the complete electronic configuration for Ca2+.

A) 1s22s22p63s24p6

B) 1s22s22p63s23p6

C) 1s22s22p63s23p5

D) 1s22s23p64s25p6

E) 1s22s2p63s2p6

10) Give the complete electronic configuration for S2-.

3

A) 1s22s22p63s24p6

B) 1s22s22p63s23p6

C) 1s22s22p63s23p5

D) 1s22s23p64s25p6

E) 1s22s2p63s2p6

11) Which of the following statements is TRUE?

A) An ionic bond is much stronger than most covalent bonds.

B) An ionic bond is formed through the sharing of electrons.

C) Ionic compounds at room temperature typically conduct electricity.

D) Once dissolved in water, ionic compounds rarely conduct electricity.

E) None of the above are true.

12) Use Lewis theory to determine the chemical formula for the compound formed between Al and O.

A) Al3O2

B) Al2O3

C) AlO2

D) Al2O

E) AlO

13) Which of the following reactions is associated with the lattice energy of Li2O (ΔH°latt)?

A) Li2O(s) → 2 Li⁺(g) + O2⁻(g)

B) 2 Li⁺(aq) + O2⁻(aq) → Li2O(s)

C) 2 Li⁺(g) + O2⁻(g) → Li2O(s)

D) Li2O(s) → 2 Li⁺(aq) + O2⁻(aq)

E) 2 Li(s) + O2(g) → Li2O(s)

14) Which of the following reactions is associated with the lattice energy of CaS (ΔH°latt)?

A) Ca(s) + S(s) → CaS(s)

B) CaS(s) → Ca(s) + S(s)

C) Ca2⁺(aq) + S2⁻(aq) → CaS(s)

D) Ca2⁺(g) + S2⁻(g) → CaS(s)

E) CaS(s) → Ca2⁺(aq) + S2⁻(aq)

15) Which of the following reactions is associated with the lattice energy of RbI (ΔH°latt)?

4

A) Rb(s) + I2(g) → RbI(s)

B) RbI(s) → Rb⁺(g) + I⁻(g)

C) RbI(s) → Rb(s) + I2(g)

D) RbI(s) → Rb⁺(aq) + I⁻(aq)

E) Rb⁺(g) + I⁻(g) → RbI(s)

16) Place the following in order of decreasing magnitude of lattice energy.

K2O Rb2S Li2O

A) Li2O > K2O > Rb2S

B) Li2O > Rb2S > K2O

C) Rb2S > K2O > Li2O

D) Rb2S > Li2O > K2O

E) K2O > Li2O > Rb2S

17) Place the following in order of decreasing magnitude of lattice energy.

NaF RbBr KCl

A) RbBr > NaF > KCl

B) NaF > KCl > RbBr

C) KCl > NaF > RbBr

D) NaF > RbBr > KCl

E) RbBr > KCl > NaF

18) Place the following in order of increasing magnitude of lattice energy.

CaO MgO SrS

A) MgO < CaO < SrS

B) SrS < MgO < CaO

C) SrS < CaO < MgO

D) CaO < MgO < SrS

E) CaO < SrS < MgO

19) Use the data given below to construct a Born-Haber cycle to determine the lattice energy of CaO.

DH°(kJ)

Ca(s) → Ca(g) 193

Ca(g) → Ca⁺(g) + e⁻ 590

Ca⁺(g) → Ca2⁺(g) + e⁻ 1010

2 O(g) → O2(g) -498

O(g) + e⁻ → O⁻(g) -141

O⁻(g) + e⁻ → O2⁻(g) 878

Ca(s) + O2(g) → CaO(s) -635

A) -3414 kJ

B) +1397 kJ

C) -2667 kJ

D) +3028 kJ

E) -2144 kJ

20) Use the data given below to construct a Born-Haber cycle to determine the electron affinity of Br.

DH°(kJ)

K(s) → K(g) 89

K(g) → K⁺(g) + e⁻ 419

Br2(l) → 2 Br(g) 193

K(s) + Br2(g) → KBr(s) -394

KBr(s) → K⁺(g) + Br⁻(g) 674

A) -885 kJ

B) -325 kJ

C) +367 kJ

D) -464 kJ

E) +246 kJ

21) Use the data given below to construct a Born-Haber cycle to determine the heat of formation of KCl.

DH°(kJ)

K(s) → K(g) 89

K(g) → K⁺(g) + e⁻ 418

Cl2(g) → 2 Cl(g) 244

Cl(g) + e⁻ → Cl⁻(g) -349

KCl(s) → K⁺(g) + Cl⁻(g) 717

A) -1119 kJ

B) -997 kJ

C) -437 kJ

D) +631 kJ

E) +158 kJ

22) Use the data given below to construct a Born-Haber cycle to determine the bond energy of O2.

DH°(kJ)

Na(s) → Na(g) 107

Na(g) → Na⁺(g) + e⁻ 496

O(g) + e⁻ → O⁻(g) -141

O⁻(g) + e⁻ → O2⁻(g) 878

2 Na(s) + O2(g) → Na2O(s) -416

2 Na⁺(g) + O2⁻(g) → Na2O(s) -2608

A) 426 kJ

B) 249 kJ

C) 852 kJ

D) 498 kJ

E) 356 kJ

23) Use the data given below to construct a Born-Haber cycle to determine the second ionization energy

of Ca.

DH°(kJ)

Ca(s) → Ca(g) 193

Ca(g) → Ca⁺(g) + e⁻ 590.

2 O(g) → O2(g) -498

O(g) + e⁻ → O⁻(g) -141

O⁻(g) + e⁻ → O2⁻(g) 878

Ca(s) + O2(g) → CaO(s) -635

Ca2⁺(g) + O2⁻(g) → CaO(s) -3414

A) 1010 kJ

B) 1757 kJ

C) 1508 kJ

D) -3027 kJ

E) -1514 kJ

24) A single covalent bond contains ________ of electrons.

A) 0 pairs

B) 1 pair

C) 2 pairs

D) 3 pairs

E) 4 pairs

25) A double covalent bond contains ________ of electrons.

A) 0 pairs

B) 1 pair

C) 2 pairs

D) 3 pairs

E) 4 pairs

26) A triple covalent bond contains ________ of electrons.

A) 0 pairs

B) 1 pair

C) 2 pairs

D) 3 pairs

E) 4 pairs

27) Identify the shortest bond.

A) single covalent bond

B) double covalent bond

C) triple covalent bond

D) all of the above bonds are the same length

28) Identify the weakest bond.

A) single covalent bond

B) double covalent bond

C) triple covalent bond

D) all of the above bonds are the same strength

29) Identify the strongest bond.

A) single covalent bond

B) double covalent bond

C) triple covalent bond

D) all of the above bonds are the same strength

30) Identify the number of bonding pairs and lone pairs of electrons in water.

A) 1 bonding pair and 1 lone pair

B) 1 bonding pair and 2 lone pairs

C) 2 bonding pairs and 2 lone pairs

D) 2 bonding pairs and 1 lone pair

E) 3 bonding pairs and 2 lone pairs

31) Identify the compound with the largest dipole moment in the gas phase.

A) Cl2

B) ClF

C) HF

D) LiF

32) Identify the compound with the smallest dipole moment in the gas phase.

A) Cl2

B) ClF

C) HF

D) LiF

33) Identify the compound with the highest percent ionic character.

A) HF

B) IBr

C) HCl

D) LiF

34) Identify the compound with the smallest percent ionic character.

A) HF

B) IBr

C) HCl

D) LiF

35) Choose the bond below that is most polar.

A) H-I

B) H-Br

C) H-F

D) H-Cl

E) C-H

36) Choose the bond below that is least polar.

A) P-F

B) C-Br

C) C-F

D) C-I

E) C-Cl

37) Using periodic trends, place the following bonds in order of increasing ionic character.

Si-P Si–Cl Si-S

A) Si-P < Si-Cl < Si-S

B) Si-P < Si-S < Si-Cl

C) Si-S < Si-Cl < Si-P

D) Si-Cl < Si-P < Si-S

E) Si-Cl < Si-S < Si-P

38) Choose the best Lewis structure for BeF2.

A)

B)

C)

D)

E)

39) Choose the best Lewis structure for OCl2.

A)

B)

C)

D)

E)

40) Choose the best Lewis structure for CH2Cl2.

A)

B)

C)

D)

E)

41) Give the number of valence electrons for CH2Cl2.

A) 16

B) 18

C) 20

D) 22

E) 12

42) Give the number of valence electrons for XeI2.

A) 22

B) 20

C) 18

D) 24

E) 16

43) Choose the best Lewis structure for XeI2.

A)

B)

C)

D)

E)

44) Give the number of valence electrons for ICl5.

A) 36

B) 40

C) 42

D) 44

E) 46

45) Choose the best Lewis structure for ICl5.

A)

B)

C)

D)

E)

46) Choose the best Lewis structure for SF4.

A)

B)

C)

D)

E)

47) Choose the best Lewis structure for BF3.

A)

B)

C)

D)

E)

48) Choose the best Lewis structure for NO3⁻.

A)

B)

C)

D)

E)

49) Give the number of valence electrons for SO42-.

A) 32

B) 30

C) 34

D) 28

E) 36

50) Choose the best Lewis structure for SO42⁻.

A)

B)

C)

D)

E)

51) Choose the best Lewis structure for PO43⁻.

A)

B)

C)

D)

E)

52) Choose the best Lewis structure for SeO42⁻.

A)

B)

C)

D)

E)

53) Choose the best Lewis structure for NH4⁺.

A)

B)

C)

D)

E)

54) Draw the Lewis structure for NO2⁻ including any valid resonance structures. Which of the

following statements is TRUE?

A) The nitrite ion contains one N—O single bond and one N=O double bond.

B) The nitrite ion contains two N—O bonds that are equivalent to 1 bonds.

C) The nitrite ion contains two N=O double bonds.

D) The nitrite ion contains two N—O single bonds.

E) None of the above are true.

55) Draw the Lewis structure for CO32- including any valid resonance structures. Which of the

following statements is TRUE?

A) The CO32- ion contains one C—O single bond and two C=O double bonds.

B) The CO32- ion contains two C—O single bonds and one C=O double bond.

C) The CO32- ion contains three C—O double bonds.

D) The CO32- ion contains two C—O single bonds and one C≡O triple bond.

E) None of the above are true.

56) Which of the following resonance structures for OCN⁻ will contribute most to the correct structure

of OCN⁻?

A) O(2 lone pairs)=C=N (2 lone pairs)

B) O(1 lone pair) ≡C—N(3 lone pairs)

C) O(1 lone pair)=C(2 lp) N(1 lone pair)

D) O(3 lone pairs)—C≡N(with 1 lone pair)

E) They all contribute equally to the correct structure of OCN⁻.

57) Using Lewis structures and formal charge, which of the following ions is most stable?

OCN⁻ ONC⁻ NOC⁻

A) OCN⁻

B) ONC⁻

C) NOC⁻

D) None of these ions are stable according to Lewis theory.

E) All of these compounds are equally stable according to Lewis theory.

58) Draw the Lewis structure for SO42⁻. How many equivalent resonance structures can be drawn?

A) 6

B) 2

C) 4

D) 3

E) 8