Deck 8: Chemical Bonds: What Makes a Gas a Greenhouse Gas

Question 1

A covalent bond results when ________

A) electrons are transferred from one atom to another atom.
B) atoms pool their electrons to form a "sea" of electrons.
C) atoms have outer electrons with the same principal quantum number.
D) electrons are shared between a pair of atoms.
E) an atom has 8 valence electrons.

Answer 1

electrons are shared between a pair of atoms.

Question 2

Based on electronegativities, which one of the following would have ionic bonds?

A) O₂
B) MgO
C) H₂O
D) CF₄
E) SiO₂

Answer 2

MgO

Question 3

Which of the following is the correct Lewis symbol for the oxide anion (O^2-)?

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

Answer 3

b

Question 4

Which statement A-D about chemical bonds is not correct?

A) Atoms combine to form molecules because the energy of the molecule is lower than the energy of the free atoms.
B) The electrostatic potential energy explains why atoms bond together.
C) The electrostatic potential energy is directly proportional to the charges on two particles.
D) The electrostatic potential energy is inversely proportional to the distance between two charged particles.
E) Statements A-D are all correct.

Question 5

How many valence electrons are there in HCl?

A) 8
B) 7
C) 6
D) 2
E) 4

Question 6

Which statement provides the best description of an ionic bond?

A) A high electron density between two positively charged atomic nuclei serves to attract the nuclei to each other.
B) The negative charge on one atom is attracted to the positive charge on a second atom.
C) Two or more electrons are attracted to each other, thereby holding the atoms together.
D) Two atomic nuclei are attracted to each other by the strong nuclear force.
E) Two atomic nuclei are attracted to each other by the Coulomb force.

Question 7

Which of the following is most likely a polar covalent bond?

A) Na __Cl
B) H __H
C) C __N
D) K __F
E) Ca __O

Question 8

Which of the following elements has 6 valence electrons?

A) C
B) S
C) N
D) Br
E) Be

Question 9

Which statement provides the best description of a covalent bond?

A) A high electron density between two positively charged atomic nuclei serves to attract the nuclei to each other.
B) The negative charge on one atom is attracted to the positive charge on a second atom.
C) Two or more electrons are attracted to each other, thereby holding the atoms together.
D) Two atomic nuclei are attracted to each other by the strong nuclear force.
E) Two atomic nuclei are attracted to each other by the Coulomb force.

Question 10

How many valence electrons does S^2- have?

A) 8
B) 6
C) 16
D) 4
E) 14

Question 11

Which type of bonding involves the sharing of valence electrons by two atoms?

A) covalent
B) ionic
C) polar ionic
D) intramolecular
E) metallic

Question 12

Indicate the ion that does not have 8 valence electrons.

A) O^-
B) Na⁺
C) Al³⁺
D) P^3-
E) Ar

Question 13

How many valence electrons are there in BrO^-?

A) 7
B) 6
C) 13
D) 14
E) 18

Question 14

Which of the following has 13 valence electrons?

A) SH^-
B) IO
C) NO
D) ICl
E) Cl₂

Question 15

How many valence electrons are contained in CO⁺?

A) 10
B) 11
C) 9
D) 8
E) 14

Question 16

Which one of the following Lewis symbols for these atoms is correct?

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

Question 17

Which statement A-D about chemical bonds is not correct?

A) The attraction of the negatively charged electrons to the positively charged nuclei causes the electrostatic potential energy to decrease as two atoms come together.
B) The repulsion of the negatively charged electrons with each other and the positively charged nuclei with each other causes the electrostatic potential energy to increase when the two atoms are very close together.
C) As two atoms come together, the electrostatic potential energy goes through a minimum. The distance between the atoms at which this minimum occurs is called the bond length.
D) The bond energy is the energy released when two atoms infinitely far apart come together at a distance that minimizes the electrostatic potential energy.
E) Statements A-D are all correct.

Question 18

How many valence electrons are there in a correctly drawn Lewis structure for formamide, HCONH₂?

A) 12
B) 14
C) 16
D) 18
E) 20

Question 19

How many valence electrons does aluminum have?

A) 1
B) 2
C) 3
D) 11
E) 13

Question 20

Which of the following ions does not have a complete valence-shell octet?

A) Al³⁺
B) I^-
C) Ca²⁺
D) Pb²⁺
E) S^2-

Question 21

Which of the following has the most valence electrons?

A) HF
B) NS
C) CN^-
D) ArF
E) ArF⁺

Question 22

Which of the following species contains a double bond?

A) NO^-
B) F₂
C) CH
D) OH^-
E) Br₂

Question 23

Which statement A-D regarding electronegativity is not correct?

A) Electronegativity is a measure of an atom's ability to attract electrons in a molecule.
B) If the electronegativity difference is sufficiently large, then an ionic bond is formed.
C) All bonds are polar except those between the same atoms (e.g., CO vs. O₂).
D) Pauling assigned electronegativity values to atoms based on their ionization energies and electron affinities.
E) Statements A-D are all correct.

Question 24

Acetonitrile (CH₃CN) is an important industrial chemical. Among other things, it is used to make plastic moldings, which have multiple uses, from car parts to Lego bricks. Which one of the following statements about acetonitrile is not correct?

A) Acetonitrile has 16 valence electrons.
B) Acetonitrile has one triple bond.
C) Acetonitrile has one pair of nonbonding electrons.
D) All atoms satisfy the octet rule in acetonitrile.
E) One carbon atom and the nitrogen atom have nonzero formal charges.

Question 25

Indicate which molecule contains the largest number of nonbonding electrons.

A) H₂
B) CO
C) N₂
D) NO
E) O₂

Question 26

Vinegar is a solution of acetic acid (C₂H₄O₂) and water. Which of the following is the Lewis structure for acetic acid?

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

Question 27

How many shared electrons are there in the Lewis structure of CN^-?

A) 3
B) 6
C) 4
D) 2
E) 10

Question 28

Carbon dioxide is a greenhouse gas. Which of the following is the correct Lewis structure for carbon dioxide?

A)
B)
C)
D)

Question 29

Which statements correctly describe a polar covalent bond?
I.Electrons are shared but not equally by the two atoms.
II. One atom has a small negative charge, and the other atom has a small positive charge.
III. The bond dipole is zero.
IV. One or more electrons are transferred from one atom to a second atom.

A) I and II only
B) II and III only
C) III and IV only
D) I and III only
E) I and IV only

Question 30

Indicate which of the following molecules has four shared electrons.

A) O₂
B) CO
C) HI
D) N₂
E) Cl₂

Question 31

Which of the following molecular ions has 3 valence electrons?

A) H₂⁺
B) He₂⁺
C) C₂⁺
D) B₂⁺
E) O₂^-

Question 32

How many covalent bonds are there in SH^-?

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

Question 33

Indicate which of the following molecules has only a single bond.

A) O₂
B) CO
C) CN^-
D) N₂
E) Cl₂

Question 34

How many lone-pair electrons are on the central oxygen atom in the Lewis structure for dinitrogen pentoxide (N₂O₅)?

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

Question 35

How many covalent bonds are there in CN^-?

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

Question 36

How many shared electron pairs are there in the Lewis structure of CN^-?

A) 3
B) 6
C) 4
D) 2
E) 10

Question 37

How many lone-pair electrons are on each of the nitrogen atoms in the Lewis structure for dinitrogen tetroxide (N₂O₄)?

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

Question 38

Identify the molecule below that contains a double bond.

A) HCN
B) O₃
C) C₂H₂
D) S₂
E) N₂

Question 39

The measure of an atom's ability to attract electrons in a chemical bond is called ________

A) hybridization.
B) ionization energy.
C) electron affinity.
D) electronegativity.
E) ionic radius.

Question 40

What types of bonds form between the chlorine and oxygen atoms of the chlorite ion (ClO₂^-) to minimize the formal charge?

A) single
B) between single and double
C) double
D) triple
E) ionic

Question 41

Which of these statements correctly describes the electronic charge distribution in a molecule?
I. The charge density around each atom is the same as it is in the free atom.
II. The electronic charge is distributed equally around each atom in the molecule.
III. Electrons are attracted preferentially to atoms with high electronegativity.
IV. Electronic charge density is enhanced in the space between atoms to form a bond.
V. Electrons are always shared between atoms and never transferred from one atom to another.

A) I only
B) II and III only
C) III and IV only
D) II only
E) V only

Question 42

Identify the molecule or ion that contains a polar covalent bond.

A) O₂
B) N₂
C) CN^-
D) H₂
E) I₂

Question 43

Which of the following bonds is most polar?

A) B--H
B) NF--H
C) P--H
D) Al--H
E) C--H

Question 44

Which sequence does not have the elements arranged correctly in order of increasing electronegativity?

A) I < Br < Cl
B) B < N < O
C) H < C < N
D) H < Li < S
E) Al < S < Cl

Question 45

Which of the following properties is typically used to identify whether a bond is polar, nonpolar, or ionic?

A) electronegativity
B) ionization energy
C) atomic radius
D) electron affinity
E) atomic mass

Question 46

Indicate the element with the smallest electronegativity.

A) Cl
B) F
C) Be
D) K
E) C

Question 47

Which group of elements is listed in order of increasing electronegativity?

A) F < Cl < Ge < Sn
B) Rb < Ca < Sc < Cs
C) Zr < V < Nb < Ta
D) Sn < P < Cl < F
E) Cl < Br < I < F

Question 48

To absorb infrared radiation, a molecule must have ________

A) a vibrational motion that causes a change in dipole moment.
B) a double or triple bond.
C) no center of symmetry, so one side is different from the other.
D) atoms other than carbon and hydrogen.
E) at least one carbon and one hydrogen atom.

Question 49

Electronegativity increases from left to right across a period because of ________

A) increased shielding of valence electrons by the core electrons.
B) an increase in the number of protons in the nucleus.
C) a decrease in the effective nuclear charge (Z_eff).
D) an increase in the shielding of core electrons by the valence electrons.
E) a decrease in the ionization potential.

Question 50

Indicate which one of the following does not contain a polar covalent bond.

A) I₂
B) CO
C) HF
D) NO
E) CN^-

Question 51

In which bond does the H atom have the highest electron density?

A) H--Cl
B) H--Li
C) H--N
D) H--O
E) H--C

Question 52

Which of these statements about greenhouse gases and the greenhouse effect is not correct?
I. Greenhouse gases prevent infrared radiation from escaping through the atmosphere.
II. To absorb infrared radiation, a molecule must have a vibration that produces a change in the dipole moment of the molecule.
III. Argon is the third most abundant species in the atmosphere (after nitrogen and oxygen), and therefore is a significant greenhouse gas.
IV. The average amount of carbon dioxide in the atmosphere increases when fossil fuels are burned, but not when ethanol (CH₃CH₂OH) produced from plants is burned.

A) I only
B) II only
C) III only
D) IV only
E) III and IV only

Question 53

In going down a column in the periodic table, the electronegativity ________

A) decreases because the valence electrons are further from the nucleus.
B) increases because the nuclear charge increases.
C) decreases because the atomic number increases.
D) increases because the ionization potential increases.
E) increases because the electron repulsion increases.

Question 54

Which of the following are listed in order of decreasing electronegativity?

A) F > S > Na > H
B) F > N > P > O
C) N > P > Si > S
D) F > Cl > Br > C
E) Te > Se > S > O

Question 55

Which of the following bonds is least polar?

A) H--O
B) H--N
C) H--B
D) H--C
E) H--F

Question 56

Indicate the element with the largest electronegativity.

A) K
B) Cs
C) Mg
D) B
E) Li

Question 57

Which of these statements correctly describes why methane and carbon dioxide are considered to be significant greenhouse gases?
I. Both have permanent dipole moments that change with vibration of the molecule.
II. Neither has a permanent dipole moment, but a dipole moment is produced when the molecule vibrates.
III. The concentration of carbon dioxide in the atmosphere increases when fossil fuels are mined and burned.

A) I only
B) II only
C) III only
D) I and III only
E) II and III only

Question 58

Which of the following bonds is definitely ionic? $$\begin{array} { l l } \text { Element } & \text { Electronegativity } \\\mathrm { C } & 2.5 \\\mathrm { O } & 3.5 \\\mathrm { H } & 2.1 \\\mathrm { Li } & 1.0\end{array}$$

A) Li--C
B) Li--H
C) Li--O
D) Li--Li
E) C--O

Question 59

In which bond does the Cl atom have the highest electron density?

A) H--Cl
B) O--Cl
C) S--Cl
D) N--Cl
E) Br--Cl

Question 60

Trends in electronegativity are primarily a result of ________

A) the number of core electrons in an element.
B) an element's atomic number.
C) the effective nuclear charge (Z_eff) that an outer electron experiences.
D) the number of valence electrons of an element.
E) the atomic mass.

Question 61

What is the total number of electrons assigned to the oxygen atom in the Lewis structure of formaldehyde (CH₂O)?

A) 8
B) 6
C) 4
D) 2
E) 10

Question 62

How many bonding electrons are assigned to the nitrogen in the Lewis structure of ammonia (NH₃)?

A) 3
B) 6
C) 5
D) 8
E) 4

Question 63

In general, resonance ________ electrons and ________ molecules.

A) delocalizes; stabilizes
B) destabilizes; destabilizes
C) localizes; stabilizes
D) delocalizes; destabilizes
E) localizes; destabilizes

Question 64

Nitrite (NO₂^-) is an important nutrient in the eutrophic zone of the ocean. Which of the following is the correct set of resonance structures for this ion?

A) I
B) II
C) III
D) IV

Question 65

Which statement A-D regarding formal charge is not correct?

A) Formal charge on an atom in a bond is determined by the electronegativity of that atom.
B) The formal charge of an atom in a molecule is the actual charge on that atom.
C) The most stable (lowest energy) Lewis structure is the one with the most formal charges equal to zero or closest to zero.
D) Any negative formal charges should be on the more or most electronegative element.
E) Statements A-D are all correct.

Question 66

When sulfur-containing fuels are burned, sulfur trioxide (SO₃) is formed in the atmosphere and contributes to acid rain (sulfur trioxide plus water produces sulfuric acid). How many resonance structures are there for SO₃ when each atom satisfies the octet rule?

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

Question 67

How many total equivalent Lewis structures are needed to describe the cyclic compound benzene, C₆H₆?

A) 1
B) 2
C) 3
D) 4
E) 5

Question 68

Urea is the main nitrogen-containing substance secreted in the urine of mammals. It is used as a fertilizer and in many industrial processes. Urea, with the chemical formula CO(NH₂)₂, has two amino groups (NH₂) bonded to a carbonyl group (C=O). Urea has three resonance Lewis structures that complete the octet for all the atoms. Which statements about these structures are correct?
I.All are equivalent.
II.All are nonequivalent.
III.Two are equivalent, and one is nonequivalent.
IV.The formal charges on all the atoms are zero in at least one structure.
V.The nitrogen-carbon and carbon-oxygen bonds all have double-bond character.

A) III and V
B) I and IV
C) II and IV
D) I and V
E) III, IV, and V

Question 69

How many total electrons are assigned to the nitrogen atom in the Lewis structure of ammonia (NH₃)?

A) 3
B) 6
C) 5
D) 8
E) 4

Question 70

O-S-S-O has three resonance Lewis structures that complete the octet for all the atoms. Which statements about these structures are correct?
I.All are equivalent.
II.All are nonequivalent.
III.Two are equivalent, and one is nonequivalent.
IV.The formal charges on all the atoms are zero in at least one structure.
V.All the bonds have double-bond character.

A) III and V
B) I and IV
C) II and IV
D) I and V
E) III, IV, and V

Question 71

The formal charge of an atom in a Lewis structure is defined as ________

A) the difference between the number of bonding electrons and nonbonding electrons assigned to an atom.
B) the difference between the number of valence electrons in a free atom and the total number of valence electrons in the molecule.
C) the difference between the number of valence electrons in a free atom and the number of electrons assigned to it in a Lewis structure.
D) the difference between the number of valence electrons in a free atom and the number of bonding electrons assigned to it.
E) the difference between the number of valence electrons in a free atom and the number of nonbonding electrons assigned to it.

Question 72

Not all the vibrations of carbon dioxide can absorb infrared radiation because ________

A) the molecule is not polar.
B) the molecule possesses a permanent dipole moment.
C) only some of the vibrations produce a transient dipole moment.
D) there are no hydrogen atoms in carbon dioxide.
E) the molecule is linear.

Question 73

Which of the following gases in the atmosphere does not contribute to the greenhouse effect?

A) CO₂
B) CO
C) H₂O
D) CH₄
E) Ar

Question 74

How many total equivalent Lewis structures are needed to describe the carbonate anion, CO₃^2-?

A) 1
B) 2
C) 3
D) 4
E) 5

Question 75

In addition to CO₂, which of the gases in the atmosphere listed below can contribute to the greenhouse effect?

A) CH₄
B) N₂
C) O₂
D) Ar
E) None of these gases can contribute to the greenhouse effect.

Question 76

Resonance structures indicate that ________

A) there is more than one allotropic form of a compound.
B) more than one ionic form of a compound exists.
C) the electronic structure is an average or superposition of the diagrams.
D) more than one isotopic form of an element exists in the molecule.
E) the molecule jumps back and forth between two or more different electronic structures.

Question 77

Which of the following molecules cannot absorb infrared radiation?

A) HCl
B) CH₄
C) N₂
D) C₆H₆
E) CO

Question 78

Which molecule has a stretching vibration that is not infrared active?

A) CO₂
B) OCS
C) H₂O
D) NH₃
E) HCl

Question 79

Ammonium nitrate (NH₄NO₃) is often used as a fertilizer. How many reasonable Lewis structures can be drawn for the ammonium ion $$\left( \mathrm { NH } _ { 4 } ^ { + } \right)$$ ?

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

Question 80

Which of these statements correctly describes the use of formal charge in choosing between possible Lewis structures to describe a molecule?
I. Formal charge on all the atoms should be zero, or at least the smallest possible value.
II. The sum of the formal charges on all the atoms should equal the charge on the molecule or ion.
III. The formal charge on an atom is not affected by the electronegativity of the atom.
IV. In an anion containing nitrogen and oxygen, the Lewis structures with a negative charge on the nitrogen will contribute the most to the description of the bonding.

A) I and II only
B) II and III only
C) III and IV only
D) I and III only
E) II and IV only