Question 1

In a Lewis structure, usually each atom acquires an outer-shell octet of electrons; H has 2 outer shell electrons.

Accepted Answer

A) True 
 B)False

Question 2

Which of the following molecules is polar?

Accepted Answer

A)  NBr3 
B)  CH4 
C)  CS2 
D)  NH4+ 
E)  PCl5 
A)  NBr3 
B)  CH4 
C)  CS2 
D)  NH4+ 
E)  PCl5

Question 3

Based on the Lewis structures, which of the following molecules would you expect to exhibit resonance?

Accepted Answer

A)  LiH 
B)  CH4 
C)  HNO2 
D)  OF2 
E)  none of these 
A)  LiH 
B)  CH4 
C)  HNO2 
D)  OF2 
E)  none of these

Question 4

After drawing the Lewis dot structure for CH2O, determine the number of single bonds, double bonds, and lone pairs on the central atom.

Accepted Answer

A)  1, 2, 0 
B)  2, 1, 1 
C)  3, 0, 1 
D)  3, 1, 0 
E)  2, 1, 0 
A)  1, 2, 0 
B)  2, 1, 1 
C)  3, 0, 1 
D)  3, 1, 0 
E)  2, 1, 0

Question 5

Polar bonds are caused by the bonding pair of electrons being attracted more to one atom than the other.

Accepted Answer

A) True 
 B)False

Question 6

Which compound would be expected to have the shortest nitrogen-nitrogen bond?

Accepted Answer

A)  H2NNH2 
B)  HNNH 
C)  N2 
D)  O2NNO2 
E)  (CH3)2NNH2 
A)  H2NNH2 
B)  HNNH 
C)  N2 
D)  O2NNO2 
E)  (CH3)2NNH2

Question 7

How many bond pairs ("bp") and how many lone pairs ("lp") should be shown in the Lewis structure for carbon monoxide?

Accepted Answer

A)  1 bp/4 lp 
B)  2 bp/3 lp 
C)  3 bp/2 lp 
D)  4 bp/1 lp 
E)  5 bp/0 lp 
A)  1 bp/4 lp 
B)  2 bp/3 lp 
C)  3 bp/2 lp 
D)  4 bp/1 lp 
E)  5 bp/0 lp

Question 8

What is the formal charge on P in PCl5?

Accepted Answer

A)  +5 
B)  +2 
C)  +1 
D)  0 
E)  -1 
A)  +5 
B)  +2 
C)  +1 
D)  0 
E)  -1

Question 9

Which of the following would be properly classified as a set of covalent molecules?

Accepted Answer

A)  NaClO4, C4H10, NH3 
B)  NaCl, CH4, S8 
C)  CO2, HCN, O2 
D)  CO2, NH4Cl, C2H6 
E)  AgCl, ScF3, P4 
A)  NaClO4, C4H10, NH3 
B)  NaCl, CH4, S8 
C)  CO2, HCN, O2 
D)  CO2, NH4Cl, C2H6 
E)  AgCl, ScF3, P4

Question 10

Which of the following has a molecular structure that can be represented without use of an "expanded octet"?

Accepted Answer

A)  Fe(CN)63- 
B)  C2Cl6 
C)  SF6 
D)  PF5 
E)  PtCl5- 
A)  Fe(CN)63- 
B)  C2Cl6 
C)  SF6 
D)  PF5 
E)  PtCl5-

Question 11

The electron-pair geometry of H2O is ________.

Accepted Answer

A)  tetrahedral 
B)  linear 
C)  trigonal planar 
D)  bent 
E)  V-shaped 
A)  tetrahedral 
B)  linear 
C)  trigonal planar 
D)  bent 
E)  V-shaped

Question 12

Choose the INCORRECT statement.

Accepted Answer

A)  Molecules with unpaired electrons are paramagnetic. 
B)  The bond order describes whether a covalent bond is single, double or triple. 
C)  A larger bond order means a shorter bond length. 
D)  Polar covalent bonds involve equal sharing of electrons in a bond. 
E)  Bonds between like atoms share electrons equally. 
A)  Molecules with unpaired electrons are paramagnetic. 
B)  The bond order describes whether a covalent bond is single, double or triple. 
C)  A larger bond order means a shorter bond length. 
D)  Polar covalent bonds involve equal sharing of electrons in a bond. 
E)  Bonds between like atoms share electrons equally.

Question 13

What is the formal charge on B in BF4-?

Accepted Answer

A)  +1 
B)  -1 
C)  +2 
D)  0 
E)  -2 
A)  +1 
B)  -1 
C)  +2 
D)  0 
E)  -2

Question 14

Given the bond enthalpies C=C (611), C≡C (837), H-H (436),C-H (414) all in kJ/mol, estimate ΔH for the following reaction: C2H2(g) + H2(g) → C2H4(g)

Accepted Answer

A)  -60 kJ 
B)  -166 kJ 
C)  -994 kJ 
D)  +166 kJ 
E)  98 kJ 
A)  -60 kJ 
B)  -166 kJ 
C)  -994 kJ 
D)  +166 kJ 
E)  98 kJ

Question 15

Given the bond enthalpies H-O (464), Cl-Cl (243), Cl-O (205), and H-Cl (431) in kJ/mol, compute ΔH° in kJ/mol for H2O(g) + Cl2(g) → HOCl(g) + HCl(g).

Accepted Answer

A)  -393 
B)  -1100 
C)  +71 
D)  +393 
E)  +1100 
A)  -393 
B)  -1100 
C)  +71 
D)  +393 
E)  +1100

Question 16

Which of the following bonds is probably the most polar?

Accepted Answer

A)  N-H in NH3 
B)  O-H in H2O 
C)  P-H in PH3 
D)  Se-H in SeH2 
E)  C-H in CH4 
A)  N-H in NH3 
B)  O-H in H2O 
C)  P-H in PH3 
D)  Se-H in SeH2 
E)  C-H in CH4

Question 17

Given the following bond lengths in pm: N-N, 145; N=N, 123; Br-Br, 228 What is the best estimate of the N-Br bond length in NBr3 in pm?

Accepted Answer

A)  373 pm 
B)  125 pm 
C)  351 pm 
D)  187 pm 
E)  561 pm 
A)  373 pm 
B)  125 pm 
C)  351 pm 
D)  187 pm 
E)  561 pm

Question 18

After drawing the Lewis dot structure for IF7, determine the number of single bonds, double bonds, and lone pairs on the central atom.

Accepted Answer

A)  3, 2, 1 
B)  7, 0, 1 
C)  7, 0, 0 
D)  1, 0, 0 
E)  4, 0, 0 
A)  3, 2, 1 
B)  7, 0, 1 
C)  7, 0, 0 
D)  1, 0, 0 
E)  4, 0, 0

Question 19

Arrange the following in order of increasing electronegativity: Cs, F, As, Cl.

Accepted Answer

A)  As < Cl < Cs < F 
B)  Cl < As < F < Cs 
C)  As < F < Cs < Cl 
D)  Cl < Cs < F < As 
E)  Cs < As < Cl < F 
A)  As < Cl < Cs < F 
B)  Cl < As < F < Cs 
C)  As < F < Cs < Cl 
D)  Cl < Cs < F < As 
E)  Cs < As < Cl < F

Question 20

Write a Lewis structure for calcium hydride.

Accepted Answer

A)    
B)    
C)    
D)  H-Ca-H 
E)  Ca-H 
A)    
B)    
C)    
D)  H-Ca-H 
E)  Ca-H

Exam 10: Chemical Bonding I: Basic Concepts

In a Lewis structure, usually each atom acquires an outer-shell octet of electrons; H has 2 outer shell electrons.

Which of the following molecules is polar?

Based on the Lewis structures, which of the following molecules would you expect to exhibit resonance?

After drawing the Lewis dot structure for CH2O, determine the number of single bonds, double bonds, and lone pairs on the central atom.

Polar bonds are caused by the bonding pair of electrons being attracted more to one atom than the other.

Which compound would be expected to have the shortest nitrogen-nitrogen bond?

How many bond pairs ("bp") and how many lone pairs ("lp") should be shown in the Lewis structure for carbon monoxide?

What is the formal charge on P in PCl5?

Which of the following would be properly classified as a set of covalent molecules?

Which of the following has a molecular structure that can be represented without use of an "expanded octet"?

The electron-pair geometry of H2O is ________.

Choose the INCORRECT statement.

What is the formal charge on B in BF4-?

Given the bond enthalpies C=C (611), C≡C (837), H-H (436),C-H (414) all in kJ/mol, estimate ΔH for the following reaction: C2H2(g) + H2(g) → C2H4(g)

Given the bond enthalpies H-O (464), Cl-Cl (243), Cl-O (205), and H-Cl (431) in kJ/mol, compute ΔH° in kJ/mol for H2O(g) + Cl2(g) → HOCl(g) + HCl(g).

Which of the following bonds is probably the most polar?

Given the following bond lengths in pm: N-N, 145; N=N, 123; Br-Br, 228 What is the best estimate of the N-Br bond length in NBr3 in pm?

After drawing the Lewis dot structure for IF7, determine the number of single bonds, double bonds, and lone pairs on the central atom.

Arrange the following in order of increasing electronegativity: Cs, F, As, Cl.

Write a Lewis structure for calcium hydride.

Matter - Its Properties and Measurement

Atoms and the Atomic Theory

Chemical Compounds

Chemical Reactions

Introduction to Reactions in Aqueous Solutions

Gases

Thermochemistry

Electrons in Atoms

The Periodic Table and Some Atomic Properties

Chemical Bonding II: Additional Aspects

Intermolecular Forces: Liquids and Solids

Solutions and Their Physical Properties

Chemical Kinetics

Principles of Chemical Equilibrium

Acids and Bases

Additional Aspects of Acid-Base Equilibria

Solubility and Complex-Ion Equilibria

Spontaneous Change: Entropy and Free Energy

Electrochemistry

Main Group Elements I: Groups 1, 2, 13, and 14

Main Group Elements II: Groups 18, 17, 16, 15, and Hydrogen

The Transition Elements

Complex Ions and Coordination Compounds

Nuclear Chemistry 1-41

Structures of Organic Compounds

Reactions of Organic Compounds

Chemistry of the Living State

Filters

After drawing the Lewis dot structure for CH₂O, determine the number of single bonds, double bonds, and lone pairs on the central atom.

The electron-pair geometry of H₂O is ________.

Given the bond enthalpies C=C (611), C≡C (837), H-H (436),C-H (414) all in kJ/mol, estimate ΔH for the following reaction: C₂H₂(g) + H₂(g) → C₂H₄(g)

Given the bond enthalpies H-O (464), Cl-Cl (243), Cl-O (205), and H-Cl (431) in kJ/mol, compute ΔH° in kJ/mol for H₂O(g) + Cl₂(g) → HOCl(g) + HCl(g).

Given the following bond lengths in pm: N-N, 145; N=N, 123; Br-Br, 228 What is the best estimate of the N-Br bond length in NBr₃ in pm?