Chemistry

Raymond Chang, Jason Overby

Chapter 10 Chemical Bonding II: Molecular Geometry and Hybridization of Atomic Orbitals - all with Video Answers

Educators

Chapter Questions

03:41

Problem 1

How is the geometry of a molecule defined and why is the study of molecular geometry important?

Arpit Gupta

Numerade Educator

03:45

Sketch the shape of a linear triatomic molecule, a trigonal planar molecule containing four atoms, a tetrahedral molecule, a trigonal bipyramidal molecule, and an octahedral molecule. Give the bond angles in each case.

Bhumika Jayee

Numerade Educator

01:11

Problem 3

How many atoms are directly bonded to the central atom in a tetrahedral molecule, a trigonal bipyramidal molecule, and an octahedral molecule?

Arpit Gupta

Numerade Educator

01:55

Problem 4

Discuss the basic features of the VSEPR model. Explain why the magnitude of repulsion decreases in the following order: lone pair-lone pair $>$ lone pair-bonding pair $>$ bonding pair-bonding pair.

Arpit Gupta

Numerade Educator

03:14

Problem 5

In the trigonal bipyramidal arrangement, why does a lone pair occupy an equatorial position rather than an axial position?

Arpit Gupta

Numerade Educator

03:26

Problem 6

The geometry of $\mathrm{CH}_{4}$ could be square planar, with the four $\mathrm{H}$ atoms at the corners of a square and the $\mathrm{C}$ atom at the center of the square. Sketch this geometry and compare its stability with that of a tetrahedral $\mathrm{CH}_{4}$ molecule.

Bhumika Jayee

Numerade Educator

03:07

Problem 7

Predict the geometries of the following species using the VSEPR method:
(a) $\mathrm{PCl}_{3}$
(b) $\mathrm{CHCl}_{3}$
(c) $\mathrm{SiH}_{4},$
(d) $\mathrm{TeCl}_{4}$.

Arpit Gupta

Numerade Educator

01:40

Problem 8

Predict the geometries of the following species:
(a) $\mathrm{AlCl}_{3},$ (b) $\mathrm{ZnCl}_{2}$, (c) $\mathrm{ZnCl}_{4}^{2-}$.

Susan Hallstrom

Numerade Educator

05:56

Problem 9

Predict the geometry of the following molecules and ion using the VSEPR model:
(a) $\mathrm{CBr}_{4},$
(b) $\mathrm{BCl}_{3}$
(c) $\mathrm{NF}_{3}$,
(d) $\mathrm{H}_{2} \mathrm{Se},$
(e) $\mathrm{NO}_{2}^{-}$.

Arpit Gupta

Numerade Educator

07:15

Problem 10

Predict the geometry of the following molecules and ion using the VSEPR model:
(a) $\mathrm{CH}_{3} \mathrm{I},$
(b) $\mathrm{ClF}_{3}$,
(c) $\mathrm{H}_{2} \mathrm{~S}$
(d) $\mathrm{SO}_{3},$
(e) $\mathrm{SO}_{4}^{2-}$

Bhumika Jayee

Numerade Educator

01:26

Problem 11

Predict the geometry of the following molecules using the VSEPR method:
(a) $\mathrm{HgBr}_{2}$,
(b) $\mathrm{N}_{2} \mathrm{O}(\mathrm{ar}-$
rangement of atoms is $\mathrm{NNO}$ ), (c) $\mathrm{SCN}^{-}$ (arrangement of atoms is $\mathrm{SCN}$ ).

Anand Jangid

Numerade Educator

11:00

Problem 12

Predict the geometries of the following ions:
(a) $\mathrm{NH}_{4}^{+}$
(b) $\mathrm{NH}_{2}^{-},$ (c) $\mathrm{CO}_{3}^{2-},$ (d) $\mathrm{ICl}_{2}^{-}$,
(e) $\mathrm{ICl}_{4}^{-}$
(f) $\mathrm{AlH}_{4}^{-},(\mathrm{g}) \mathrm{SnCl}_{5}^{-}$
(h) $\mathrm{H}_{3} \mathrm{O}^{+}$
(i) $\mathrm{BeF}_{4}^{2-}$.

Bhumika Jayee

Numerade Educator

01:30

Problem 13

Describe the geometry around each of the three central atoms in the $\mathrm{CH}_{3} \mathrm{COOH}$ molecule.

Arpit Gupta

Numerade Educator

03:20

Problem 14

Which of the following species are tetrahedral? $\mathrm{SiCl}_{4}, \mathrm{SeF}_{4}, \mathrm{XeF}_{4}, \mathrm{Cl}_{4}, \mathrm{CdCl}_{4}^{2-}$

Nicole Krahulik

Numerade Educator

01:23

Problem 15

Define dipole moment. What are the units and symbol for dipole moment?

Ryan Scripp

Numerade Educator

04:39

Problem 16

What is the relationship between the dipole moment and the bond moment? How is it possible for a molecule to have bond moments and yet be nonpolar?

Bhumika Jayee

Numerade Educator

01:38

Problem 17

Explain why an atom cannot have a permanent dipole moment.

Arpit Gupta

Numerade Educator

02:38

Problem 18

The bonds in beryllium hydride $\left(\mathrm{BeH}_{2}\right)$ molecules are polar, and yet the dipole moment of the molecule is zero. Explain.

Bhumika Jayee

Numerade Educator

02:26

Problem 19

Referring to Table 10.3 , arrange the following molecules in order of increasing dipole moment: $\mathrm{H}_{2} \mathrm{O}$ $\mathrm{H}_{2} \mathrm{~S}, \mathrm{H}_{2} \mathrm{Te}, \mathrm{H}_{2} \mathrm{Se}$

Ryan Scripp

Numerade Educator

02:54

Problem 20

The dipole moments of the hydrogen halides decrease from HF to HI (see Table 10.3). Explain this trend.

Bhumika Jayee

Numerade Educator

03:23

Problem 21

List the following molecules in order of increasing dipole moment: $\mathrm{H}_{2} \mathrm{O}, \mathrm{CBr}_{4}, \mathrm{H}_{2} \mathrm{~S}, \mathrm{HF}, \mathrm{NH}_{3}, \mathrm{CO}_{2}$

Ryan Scripp

Numerade Educator

03:12

Problem 22

Does the molecule OCS have a higher or lower dipole moment than $\mathrm{CS}_{2} ?$

Bhumika Jayee

Numerade Educator

01:06

Problem 23

Which of the molecules (a) or (b) has a higher dipole moment?
(a)
(b)

Nicole Krahulik

Numerade Educator

01:04

Problem 24

Arrange the following compounds in order of increasing dipole moment:
(a)
(b)
(c)
(d)

Nicole Krahulik

Numerade Educator

04:07

Problem 25

What is valence bond theory? How does it differ from the Lewis concept of chemical bonding?

Arpit Gupta

Numerade Educator

04:01

Problem 26

Use valence bond theory to explain the bonding in $\mathrm{Cl}_{2}$ and $\mathrm{HCl}$. Show how the atomic orbitals overlap when a bond is formed.

Arpit Gupta

Numerade Educator

01:40

Problem 27

Draw a potential energy curve for the bond formation in $\mathrm{F}_{2}$

Ryan Scripp

Numerade Educator

02:58

Problem 28

What is the hybridization of atomic orbitals? Why is it impossible for an isolated atom to exist in the hybridized state?

Arpit Gupta

Numerade Educator

01:51

Problem 29

How does a hybrid orbital differ from a pure atomic orbital? Can two $2 p$ orbitals of an atom hybridize to give two hybridized orbitals?

Emily Himsel

Numerade Educator

00:47

Problem 30

What is the angle between the following two hybrid orbitals on the same atom? (a) $s p$ and $s p$ hybrid orbitals, (b) $s p^{2}$ and $s p^{2}$ hybrid orbitals, (c) $s p^{3}$ and $s p^{3}$ hybrid orbitals.

Arpit Gupta

Numerade Educator

01:18

Problem 31

Describe the bonding scheme of the AsH $_{3}$ molecule in terms of hybridization.

Arpit Gupta

Numerade Educator

01:35

Problem 32

What is the hybridization state of $\mathrm{Si}$ in $\mathrm{SiH}_{4}$ and in $\mathrm{H}_{3} \mathrm{Si}-\mathrm{SiH}_{3} ?$

Bhumika Jayee

Numerade Educator

00:58

Problem 33

Describe the change in hybridization (if any) of the Al atom in the following reaction:
$$
\mathrm{AlCl}_{3}+\mathrm{Cl}^{-} \longrightarrow \mathrm{AlCl}_{4}^{-}
$$

Arpit Gupta

Numerade Educator

02:49

Problem 34

Consider the reaction
$$
\mathrm{BF}_{3}+\mathrm{NH}_{3} \longrightarrow \mathrm{F}_{3} \mathrm{~B}-\mathrm{NH}_{3}
$$
Describe the changes in hybridization (if any) of the $\mathrm{B}$ and $\mathrm{N}$ atoms as a result of this reaction.

Arpit Gupta

Numerade Educator

01:41

Problem 35

What hybrid orbitals are used by nitrogen atoms in the following species?
(a) $\mathrm{NH}_{3}$,
(b) $\mathrm{H}_{2} \mathrm{~N}-\mathrm{NH}_{2}$
(c) $\mathrm{NO}_{3}^{-}$

Arpit Gupta

Numerade Educator

01:07

Problem 36

Describe the hybridization of phosphorus in $\mathrm{PF}_{5}$.

Arpit Gupta

Numerade Educator

01:40

Problem 37

Give the formula of a cation comprised of iodine and fluorine in which the iodine atom is $s p^{3}$ $d$ -hybridized.

Lijeesh Krishnan

Numerade Educator

01:18

Problem 38

Give the formula of an anion comprised of iodine and fluorine in which the iodine atom is $s p^{3}$ $d^{2}$ -hybridized.

Anand Jangid

Numerade Educator

04:13

Problem 39

How would you distinguish between a sigma bond and a pi bond?

Arpit Gupta

Numerade Educator

02:51

Problem 40

What are the hybrid orbitals of the carbon atoms in the following molecules?
(a) $\mathrm{H}_{3} \mathrm{C}-\mathrm{CH}_{3}$
(b) $\mathrm{H}_{3} \mathrm{C}-\mathrm{CH}=\mathrm{CH}_{2}$
(c) $\mathrm{CH}_{3}-\mathrm{C} \equiv \mathrm{C}-\mathrm{CH}_{2} \mathrm{OH}$
(d) $\mathrm{CH}_{3} \mathrm{CH}=\mathrm{O}$
(e) $\mathrm{CH}_{3} \mathrm{COOH}$

Arpit Gupta

Numerade Educator

01:59

Problem 41

Specify which hybrid orbitals are used by carbon atoms in the following species:
(a) $\mathrm{CO}$,
(b) $\mathrm{CO}_{2}$,
(c) $\mathrm{CN}^{-}$.

Arpit Gupta

Numerade Educator

01:20

Problem 42

What is the hybridization state of the central $\mathrm{N}$ atom in the azide ion, $\mathrm{N}_{3}^{-} ?$ (Arrangement of atoms: NNN.)

Bhumika Jayee

Numerade Educator

03:18

Problem 43

The allene molecule $\mathrm{H}_{2} \mathrm{C}=\mathrm{C}=\mathrm{CH}_{2}$ is linear (the three $\mathrm{C}$ atoms lie on a straight line $) .$ What are the hybridization states of the carbon atoms? Draw diagrams to show the formation of sigma bonds and pi bonds in allene.

Arpit Gupta

Numerade Educator

01:25

Problem 44

How many pi bonds and sigma bonds are there in the tetracyanoethylene molecule?

Bhumika Jayee

Numerade Educator

01:04

Problem 45

How many sigma bonds and pi bonds are there in each of the molecules (a), (b), and (c)?
(a)
(b)
(c)

Crystal Wang

Numerade Educator

05:49

Problem 46

What is molecular orbital theory? How does it differ from valence bond theory?

Arpit Gupta

Numerade Educator

03:59

Problem 47

Sketch the shapes of the following molecular orbitals:
$\sigma_{1 s}, \sigma_{1 s}^{\star}, \pi_{2 p},$ and $\pi_{2 p}^{\star} .$ How do their energies compare?

Bhumika Jayee

Numerade Educator

02:40

Problem 48

Explain the significance of bond order. Can bond order be used for quantitative comparisons of the strengths of chemical bonds?

Bhumika Jayee

Numerade Educator

01:12

Problem 49

Explain in molecular orbital terms the changes in $\mathrm{H}-\mathrm{H}$ internuclear distance that occur as the $\mathrm{mo}-$ lecular $\mathrm{H}_{2}$ is ionized first to $\mathrm{H}_{2}^{+}$ and then to $\mathrm{H}_{2}^{2+}$.

Anand Jangid

Numerade Educator

00:35

Problem 50

The formation of $\mathrm{H}_{2}$ from two $\mathrm{H}$ atoms is an energetically favorable process. Yet statistically there is less than a 100 percent chance that any two $\mathrm{H}$ atoms will undergo the reaction. Apart from energy considerations, how would you account for this observation based on the electron spins in the two $\mathrm{H}$ atoms?

Arpit Gupta

Numerade Educator

03:53

Problem 51

Draw a molecular orbital energy level diagram for each of the following species: $\mathrm{He}_{2}, \mathrm{HHe}, \mathrm{He}_{2}^{+}$ Compare their relative stabilities in terms of bond orders. (Treat HHe as a diatomic molecule with three electrons.)

Arpit Gupta

Numerade Educator

03:10

Problem 52

Arrange the following species in order of increasing stability: $\mathrm{Li}_{2}, \mathrm{Li}_{2}^{+}, \mathrm{Li}_{2}^{-}$. Justify your choice with a molecular orbital energy level diagram.

Arpit Gupta

Numerade Educator

01:07

Problem 53

Use molecular orbital theory to explain why the $\mathrm{Be}_{2}$ molecule does not exist.

Arpit Gupta

Numerade Educator

03:54

Problem 54

Which of these species has a longer bond, $\mathrm{B}_{2}$ or $\mathrm{B}_{2}^{+} ?$ Explain in terms of molecular orbital theory.

Bhumika Jayee

Numerade Educator

03:32

Problem 55

Acetylene $\left(\mathrm{C}_{2} \mathrm{H}_{2}\right)$ has a tendency to lose two protons $\left(\mathrm{H}^{+}\right)$ and form the carbide ion $\left(\mathrm{C}_{2}^{2-}\right),$ which is present in a number of ionic compounds, such as $\mathrm{CaC}_{2}$ and $\mathrm{MgC}_{2}$. Describe the bonding scheme in the $\mathrm{C}_{2}^{2-}$ ion in terms of molecular orbital theory. Compare the bond order in $\mathrm{C}_{2}^{2-}$ with that in $\mathrm{C}_{2}$.

Arpit Gupta

Numerade Educator

01:28

Problem 56

Compare the Lewis and molecular orbital treatments of the oxygen molecule.

Prashant Bana

Numerade Educator

05:54

Problem 57

Explain why the bond order of $\mathrm{N}_{2}$ is greater than that of $\mathrm{N}_{2}^{+}$, but the bond order of $\mathrm{O}_{2}$ is less than that of $\mathrm{O}_{2}^{+}$

Arpit Gupta

Numerade Educator

09:32

Problem 58

Compare the relative stability of the following species and indicate their magnetic properties (that is, diamagnetic or paramagnetic): $\mathrm{O}_{2}, \mathrm{O}_{2}^{+}, \mathrm{O}_{2}^{-}$ (superoxide ion), $\mathrm{O}_{2}^{2-}$ (peroxide ion).

Bhumika Jayee

Numerade Educator

03:48

Problem 59

Use molecular orbital theory to compare the relative stabilities of $\mathrm{F}_{2}$ and $\mathrm{F}_{2}^{+}$

Arpit Gupta

Numerade Educator

04:47

Problem 60

A single bond is almost always a sigma bond, and a double bond is almost always made up of a sigma bond and a pi bond. There are very few exceptions to this rule. Show that the $\mathrm{B}_{2}$ and $\mathrm{C}_{2}$ molecules are examples of the exceptions.

Bhumika Jayee

Numerade Educator

02:27

Problem 61

In 2009 the ion $\mathrm{N}_{2}^{3-}$ was isolated. Use a molecular orbital diagram to compare its properties (bond order and magnetism) with the isoelectronic ion $\mathrm{O}_{2}^{-}$

Madi Sousa

Numerade Educator

05:29

Problem 62

The following potential energy curve represents the formation of $\mathrm{F}_{2}$ from two $\mathrm{F}$ atoms. Describe the state of bonding at the marked regions.

Bhumika Jayee

Numerade Educator

03:03

Problem 63

How does a delocalized molecular orbital differ from a molecular orbital such as that found in $\mathrm{H}_{2}$ or $\mathrm{C}_{2} \mathrm{H}_{4} ?$ What do you think are the minimum conditions (for example, number of atoms and types of orbitals) for forming a delocalized molecular orbital?

Arpit Gupta

Numerade Educator

02:53

Problem 64

In Chapter 9 we saw that the resonance concept is useful for dealing with species such as the benzene molecule and the carbonate ion. How does molecular orbital theory deal with these species?

Bhumika Jayee

Numerade Educator

02:04

Problem 65

Both ethylene $\left(\mathrm{C}_{2} \mathrm{H}_{4}\right)$ and benzene $\left(\mathrm{C}_{6} \mathrm{H}_{6}\right)$ contain the $\mathrm{C}=\mathrm{C}$ bond. The reactivity of ethylene is greater than that of benzene. For example, ethylene readily reacts with molecular bromine, whereas benzene is normally quite inert toward molecular bromine and many other compounds. Explain this difference in reactivity.

Arpit Gupta

Numerade Educator

01:19

Problem 66

Explain why the symbol on the left is a better representation of benzene molecules than that on the
right.

Arpit Gupta

Numerade Educator

05:34

Problem 67

Determine which of these molecules has a more delocalized orbital and justify your choice.
(Hint: Both molecules contain two benzene rings. In naphthalene, the two rings are fused together. In biphenyl, the two rings are joined by a single bond, around which the two rings can rotate.)

Dr. Satish Ingale

Numerade Educator

03:53

Problem 68

Nitryl fluoride (FNO $_{2}$ ) is very reactive chemically. The fluorine and oxygen atoms are bonded to the nitrogen atom.
(a) Write a Lewis structure for FNO $_{2}$.
(b) Indicate the hybridization of the nitrogen atom.
(c) Describe the bonding in terms of molecular orbital theory. Where would you expect delocalized molecular orbitals to form?

Bhumika Jayee

Numerade Educator

View

Problem 69

Describe the bonding in the nitrate ion $\mathrm{NO}_{3}^{-}$ in terms of delocalized molecular orbitals.

Jean Gephart

Numerade Educator

02:04

Problem 70

What is the state of hybridization of the central $\mathrm{O}$ atom in $\mathrm{O}_{3} ?$ Describe the bonding in $\mathrm{O}_{3}$ in terms of delocalized molecular orbitals.

Arpit Gupta

Numerade Educator

01:55

Problem 71

Which of the following species is not likely to have a tetrahedral shape?
(a) $\operatorname{SiBr}_{4},$
(b) $\mathrm{NF}_{4}^{+}$
(c) $\mathrm{SF}_{4}$
(d) $\mathrm{BeCl}_{4}^{2-},$
(e) $\mathrm{BF}_{4}^{-},$ (f) $\mathrm{AlCl}_{4}^{-}$

Arpit Gupta

Numerade Educator

02:16

Problem 72

Draw the Lewis structure of mercury(II) bromide. Is this molecule linear or bent? How would you establish its geometry?

Bhumika Jayee

Numerade Educator

02:56

Problem 73

Sketch the bond moments and resultant dipole moments for the following molecules: $\mathrm{H}_{2} \mathrm{O}, \mathrm{PCl}_{3},$ $\mathrm{XeF}_{4}, \mathrm{PCl}_{5}, \mathrm{SF}_{6}$

Ryan Scripp

Numerade Educator

02:00

Problem 74

Although both carbon and silicon are in Group $4 \mathrm{~A}$, very few $\mathrm{Si}=\mathrm{Si}$ bonds are known. Account for the instability of silicon-to-silicon double bonds in general. (Hint: Compare the atomic radii of $\mathrm{C}$ and $\mathrm{Si}$ in Figure $8.5 .$ What effect would the larger size have on pi bond formation?)

Bhumika Jayee

Numerade Educator

02:04

Problem 75

Acetaminophen is the active ingredient in Tylenol.
(a) Write the molecular formula of the compound.
(b) What is the hybridization state of each $\mathrm{C}, \mathrm{N},$ and $\mathrm{O}$ atom?
(c) Describe the geometry about each $\mathrm{C}, \mathrm{N}$, and $\mathrm{O}$ atom.

Ryan Scripp

Numerade Educator

09:30

Problem 76

Caffeine is a stimulant drug present in coffee.
(a) Write the molecular formula of the compound.
(b) What is the hybridization state of each $\mathrm{C}, \mathrm{N},$ and O atom?
(c) Describe the geometry about each $\mathrm{C}, \mathrm{N}$, and $\mathrm{O}$ atom.

Bhumika Jayee

Numerade Educator

02:20

Problem 77

Predict the geometry of sulfur dichloride $\left(\mathrm{SCl}_{2}\right)$ and the hybridization of the sulfur atom.

Shazia Naz

Numerade Educator

04:15

Problem 78

Antimony pentafluoride, $\mathrm{SbF}_{5}$, reacts with $\mathrm{XeF}_{4}$ and $\mathrm{XeF}_{6}$ to form ionic compounds, $\mathrm{XeF}_{3}^{+} \mathrm{SbF}_{6}-$ and $\mathrm{XeF}_{5}^{+} \mathrm{SbF}_{6}^{-} .$ Describe the geometries of the cations and anion in these two compounds.

Arpit Gupta

Numerade Educator

06:55

Problem 79

Draw Lewis structures and give the other information requested for the following molecules: (a) $\mathrm{BF}_{3}$. Shape: planar or nonplanar? (b) $\mathrm{ClO}_{3}^{-}$. Shape: planar or nonplanar? (c) $\mathrm{H}_{2} \mathrm{O}$. Show the direction of the resultant dipole moment. (d) $\mathrm{OF}_{2}$. Polar or nonpolar molecule?
(e) $\mathrm{NO}_{2}$. Estimate the ONO bond angle.

Ryan Scripp

Numerade Educator

04:16

Problem 80

Predict the bond angles for the following molecules:
(a) $\mathrm{BeCl}_{2},$ (b) $\mathrm{BCl}_{3},$
(c) $\mathrm{CCl}_{4}$,
(d) $\mathrm{CH}_{3} \mathrm{Cl}$,
(e) $\mathrm{Hg}_{2} \mathrm{Cl}_{2}$
(arrangement of atoms: $\mathrm{ClHgHgCl}$ ),
(f) $\mathrm{SnCl}_{2}$,
(g) $\mathrm{H}_{2} \mathrm{O}_{2},$ (h) $\mathrm{SnH}_{4}$.

Bhumika Jayee

Numerade Educator

05:51

Problem 81

Briefly compare the VSEPR and hybridization approaches to the study of molecular geometry.

Arpit Gupta

Numerade Educator

01:10

Problem 82

Describe the hybridization state of arsenic in arsenic

Anand Jangid

Numerade Educator

04:43

Problem 83

Draw Lewis structures and give the other information requested for the following: (a) $\mathrm{SO}_{3}$. Polar or nonpolar molecule? (b) $\mathrm{PF}_{3}$. Polar or nonpolar molecule? (c) $\mathrm{F}_{3} \mathrm{SiH}$. Show the direction of the resultant dipole moment.
(d) $\mathrm{SiH}_{3}^{-}$. Planar or pyramidal shape?
(e) $\mathrm{Br}_{2} \mathrm{CH}_{2}$. Polar or nonpolar molecule?

Ryan Scripp

Numerade Educator

04:46

Problem 84

Which of the following molecules and ions are linear? $\mathrm{ICl}_{2}^{-}, \mathrm{IF}_{2}^{+}, \mathrm{OF}_{2}, \mathrm{SnI}_{2}, \mathrm{CdBr}_{2}$

Bhumika Jayee

Numerade Educator

02:22

Problem 85

Draw the Lewis structure for the $\mathrm{BeCl}_{4}^{2-}$ ion. Predict its geometry and describe the hybridization state of the Be atom.

Arpit Gupta

Numerade Educator

02:16

Problem 86

The $\mathrm{N}_{2} \mathrm{~F}_{2}$ molecule can exist in either of the following two forms:
(a) What is the hybridization of $\mathrm{N}$ in the molecule?
(b) Which structure has a dipole moment?

Bhumika Jayee

Numerade Educator

01:24

Problem 87

Cyclopropane $\left(\mathrm{C}_{3} \mathrm{H}_{6}\right)$ has the shape of a triangle in which a $\mathrm{C}$ atom is bonded to two $\mathrm{H}$ atoms and two other $\mathrm{C}$ atoms at each corner. Cubane $\left(\mathrm{C}_{8} \mathrm{H}_{8}\right)$ has the shape of a cube in which a $\mathrm{C}$ atom is bonded to one $\mathrm{H}$ atom and three other $\mathrm{C}$ atoms at each corner.
(a) Draw Lewis structures of these molecules.
(b) Compare the CCC angles in these molecules with those predicted for an $s p^{3}$ -hybridized $\mathrm{C}$ atom.
(c) Would you expect these molecules to be easy to make?

Arpit Gupta

Numerade Educator

01:14

Problem 88

The compound 1,2 -dichloroethane $\left(\mathrm{C}_{2} \mathrm{H}_{4} \mathrm{Cl}_{2}\right)$ is nonpolar, while $c i s$ -dichloroethylene $\left(\mathrm{C}_{2} \mathrm{H}_{2} \mathrm{Cl}_{2}\right)$ has a dipole moment:
The reason for the difference is that groups connected by a single bond can rotate with respect to each other, but no rotation occurs when a double bond connects the groups. On the basis of bonding considerations, explain why rotation occurs in 1,2 -dichloroethane but not in $c i s$ -dichloroethylene.

Anand Jangid

Numerade Educator

01:04

Problem 89

Does the following molecule have a dipole moment?
(Hint: See the answer to Problem 10.39.)

Madi Sousa

Numerade Educator

02:02

Problem 90

So-called greenhouse gases, which contribute to global warming, have a dipole moment or can be bent or distorted into shapes that have a dipole moment. Which of the following gases are greenhouse gases: $\mathrm{N}_{2}, \mathrm{O}_{2}, \mathrm{O}_{3}, \mathrm{CO}, \mathrm{CO}_{2}, \mathrm{NO}_{2}, \mathrm{~N}_{2} \mathrm{O},$
$\mathrm{CH}_{4}, \mathrm{CFCl}_{3} ?$

Crystal Wang

Numerade Educator

01:06

Problem 91

The bond angle of $\mathrm{SO}_{2}$ is very close to $120^{\circ},$ even though there is a lone pair on $\mathrm{S} .$ Explain.

Arpit Gupta

Numerade Educator

01:59

Problem 92

$3^{\prime}$ -azido- $3^{\prime}$ -deoxythymidine, shown here, commonly known as AZT, is one of the drugs used to treat acquired immune deficiency syndrome (AIDS). What are the hybridization states of the C and $\mathrm{N}$ atoms in this molecule?

Crystal Wang

Numerade Educator

00:29

Problem 93

The following molecules $\left(\mathrm{A} \mathrm{X}_{4} \mathrm{Y}_{2}\right)$ all have octahedral geometry. Group the molecules that are equivalent to each other.

Arpit Gupta

Numerade Educator

01:18

Problem 94

The compounds carbon tetrachloride $\left(\mathrm{CCl}_{4}\right)$ and silicon tetrachloride $\left(\mathrm{SiCl}_{4}\right)$ are similar in geometry and hybridization. However, $\mathrm{CCl}_{4}$ does not react with water but $\mathrm{SiCl}_{4}$ does. Explain the difference in their chemical reactivities. (Hint: The first step of the reaction is believed to be the addition of a water molecule to the $\mathrm{Si}$ atom in $\left.\mathrm{SiCl}_{4} .\right)$

Arpit Gupta

Numerade Educator

01:14

Problem 95

Write the ground-state electron configuration for $\mathrm{B}_{2}$. Is the molecule diamagnetic or paramagnetic?

Arpit Gupta

Numerade Educator

02:01

Problem 96

What are the hybridization states of the $\mathrm{C}$ and $\mathrm{N}$ atoms in this molecule?

Bhumika Jayee

Numerade Educator

02:39

Problem 97

Use molecular orbital theory to explain the difference between the bond enthalpies of $\mathrm{F}_{2}$ and $\mathrm{F}_{2}^{-}$ (see Problem 9.116 ).

Madi Sousa

Numerade Educator

05:22

Problem 98

Referring to the Chemistry in Action essay "Microwave Ovens-Dipole Moments at Work" in Section $10.2,$ answer the following questions:
(a) If you wanted to cook a roast (beef or lamb), would you use a microwave oven or a conventional oven?
(b) Radar is a means of locating an object by measuring the time for the echo of a microwave from the object to return to the source and the direction from which it returns. Would radar work if oxygen, nitrogen, and carbon dioxide were polar molecules? (c) In early tests of radar at the English Channel during World War II, the results were inconclusive even though there was no equipment malfunction. Why? (Hint: The weather is often foggy in the region.)

Susan Hallstrom

Numerade Educator

01:19

Problem 99

Which of the molecules (a)-(c) are polar?
(a)
(b)
(c)

Nicole Krahulik

Numerade Educator

01:52

Problem 100

Which of the molecules (a)-(c) are polar?
(a)
(b)
(c)

Nicole Krahulik

Numerade Educator

02:23

Problem 101

The stable allotropic form of phosphorus is $\mathrm{P}_{4},$ in which each $\mathrm{P}$ atom is bonded to three other $\mathrm{P}$ atoms. Draw a Lewis structure of this molecule and describe its geometry. At high temperatures, $\mathrm{P}_{4}$ dissociates to form $\mathrm{P}_{2}$ molecules containing a $\mathrm{P}=\mathrm{P}$ bond. Explain why $\mathrm{P}_{4}$ is more stable than $\mathrm{P}_{2}$.

Arpit Gupta

Numerade Educator

02:49

Problem 102

Referring to Table $9.4,$ explain why the bond enthalpy for $\mathrm{Cl}_{2}$ is greater than that for $\mathrm{F}_{2}$. (Hint: The bond lengths of $\mathrm{F}_{2}$ and $\mathrm{Cl}_{2}$ are $142 \mathrm{pm}$ and $199 \mathrm{pm}$ respectively.)

Bhumika Jayee

Numerade Educator

02:21

Problem 103

Use molecular orbital theory to explain the bonding in the azide ion $\left(\mathrm{N}_{3}^{-}\right) .$ (Arrangement of atoms is NNN.)

Arpit Gupta

Numerade Educator

03:55

Problem 104

The ionic character of the bond in a diatomic molecule can be estimated by the formula
$$
\frac{\mu}{e d} \times 100 \%
$$
where $\mu$ is the experimentally measured dipole moment (in $\mathrm{C} \mathrm{m}$ ), $e$ the electronic charge, and $d$ the bond length in meters. (The quantity $e d$ is the hypothetical dipole moment for the case in which the transfer of an electron from the less electronegative to the more electronegative atom is complete.) Given that the dipole moment and bond length of HF are $1.92 \mathrm{D}$ and $91.7 \mathrm{pm}$, respectively, calculate the percent ionic character of the molecule.

Bhumika Jayee

Numerade Educator

01:49

Problem 105

Draw three Lewis structures for compounds with the formula $\mathrm{C}_{2} \mathrm{H}_{2} \mathrm{~F}_{2} .$ Indicate which of the compound(s) are polar.

Madi Sousa

Numerade Educator

02:35

Problem 106

Greenhouse gases absorb (and trap) outgoing infrared radiation (heat) from Earth and contribute to global warming. The molecule of a greenhouse gas either possesses a permanent dipole moment or has a changing dipole moment during its vibrational motions. Consider three of the vibrational modes of carbon dioxide,

where the arrows indicate the movement of the atoms. (During a complete cycle of vibration, the atoms move toward one extreme position and then reverse their direction to the other extreme position.) Which of the preceding vibrations are responsible for $\mathrm{CO}_{2}$ to behave as a greenhouse gas? Which of the following molecules can act as a greenhouse gas: $\mathrm{N}_{2}, \mathrm{O}_{2}, \mathrm{CO}, \mathrm{NO}_{2},$ and $\mathrm{N}_{2} \mathrm{O} ?$

Bhumika Jayee

Numerade Educator

01:13

Problem 107

Aluminum trichloride $\left(\mathrm{AlCl}_{3}\right)$ is an electrondeficient molecule. It has a tendency to form a dimer (a molecule made of two $\mathrm{AlCl}_{3}$ units):
$$
\mathrm{AlCl}_{3}+\mathrm{AlCl}_{3} \longrightarrow \mathrm{Al}_{2} \mathrm{Cl}_{6}
$$
(a) Draw a Lewis structure for the dimer. (b) Describe the hybridization state of $\mathrm{Al}$ in $\mathrm{AlCl}_{3}$ and $\mathrm{Al}_{2} \mathrm{Cl}_{6}$.
(c) Sketch the geometry of the dimer.
(d) Do these molecules possess a dipole moment?

Anand Jangid

Numerade Educator

07:19

Problem 108

The molecules $c i s$ -dichloroethylene and transdichloroethylene shown in Section 10.2 can be interconverted by heating or irradiation. (a) Starting with cis-dichloroethylene, show that rotating the $\mathrm{C}=\mathrm{C}$ bond by $180^{\circ}$ will break only the pi bond but will leave the sigma bond intact. Explain the formation of trans-dichloroethylene from this process. (Treat the rotation as two stepwise $90^{\circ}$ rotations. $(\mathrm{b})$ Account for the difference in the bond enthalpies for the pi bond (about $270 \mathrm{~kJ} / \mathrm{mol}$ ) and the sigma bond (about $350 \mathrm{~kJ} /$ mol). (c) Calculate the longest wavelength of light needed to bring about this conversion.

Susan Hallstrom

Numerade Educator

01:26

Problem 109

Progesterone is a hormone responsible for female sex characteristics. In the usual shorthand structure, each point where lines meet represent a C atom, and most H atoms are not shown. Draw the complete structure of the molecule, showing all $\mathrm{C}$ and $\mathrm{H}$ atoms. Indicate which $\mathrm{C}$ atoms are $s p^{2}-$ and $s p^{3}$ -hybridized.

Madi Sousa

Numerade Educator

09:43

Problem 110

For each pair listed here, state which one has a higher first ionization energy and explain your choice:
(a) $\mathrm{H}$ or $\mathrm{H}_{2},$ (b) $\mathrm{N}$ or $\mathrm{N}_{2},$ (c) $\mathrm{O}$ or $\mathrm{O}_{2},$ (d) $\mathrm{F}$ or $\mathrm{F}_{2}$.

Bhumika Jayee

Numerade Educator

01:05

Problem 111

The molecule benzyne $\left(\mathrm{C}_{6} \mathrm{H}_{4}\right)$ is a very reactive species. It resembles benzene in that it has a sixmembered ring of carbon atoms. Draw a Lewis structure of the molecule and account for the molecule's high reactivity.

Madi Sousa

Numerade Educator

03:40

Problem 112

Assume that the third-period element phosphorus forms a diatomic molecule, $\mathrm{P}_{2}$, in an analogous way as nitrogen does to form $\mathrm{N}_{2}$. (a) Write the electronic configuration for $\mathrm{P}_{2}$. Use $\left[\mathrm{Ne}_{2}\right]$ to represent the electron configuration for the first two periods.
(b) Calculate its bond order. (c) What are its magnetic properties (diamagnetic or paramagnetic)?

Bhumika Jayee

Numerade Educator

02:57

Problem 113

Consider a $\mathrm{N}_{2}$ molecule in its first excited electronic state, that is, when an electron in the highest occupied molecular orbital is promoted to the lowest empty molecular orbital.
(a) Identify the molecular orbitals involved and sketch a diagram to show the transition. (b) Compare the bond order and bond length of $\mathrm{N}_{2}^{*}$ with $\mathrm{N}_{2},$ where the asterisk denotes the excited molecule. (c) Is $\mathrm{N}_{2}{ }^{*}$ diamagnetic or paramagnetic? (d) When $\mathrm{N}_{2}$ * loses its excess energy and converts to the ground state $\mathrm{N}_{2}$, it emits a photon of wavelength $470 \mathrm{nm},$ which makes up part of the auroras lights. Calculate the energy difference between these levels.

Madi Sousa

Numerade Educator

04:26

Problem 114

As mentioned in the chapter, the Lewis structure for $\mathrm{O}_{2}$ is
Use the molecular orbital theory to show that the structure actually corresponds to an excited state of the oxygen molecule.

Bhumika Jayee

Numerade Educator

02:26

Problem 115

Referring to Problem 9.143 , describe the hybridization state of the $\mathrm{N}$ atoms and the overall shape of the ion.

Nicole Krahulik

Numerade Educator

05:37

Problem 116

Describe the geometry and hybridization for the reactants and product in the following reaction:
$$
\mathrm{ClF}_{3}+\mathrm{AsF}_{5} \longrightarrow\left[\mathrm{ClF}_{2}^{+}\right]\left[\mathrm{AsF}_{6}^{-}\right]
$$

Bhumika Jayee

Numerade Educator

02:54

Problem 117

Draw the Lewis structure of ketene $\left(\mathrm{C}_{2} \mathrm{H}_{2} \mathrm{O}\right)$ and describe the hybridization states of the $\mathrm{C}$ atoms. The molecule does not contain $\mathrm{O}-\mathrm{H}$ bonds. On separate diagrams, sketch the formation of sigma and pi bonds.

Arpit Gupta

Numerade Educator

03:07

Problem 118

$\mathrm{TCDD},$ or 2,3,7,8 -tetrachlorodibenzo- $p$ -dioxin, is a highly toxic compound:
It gained considerable notoriety in 2004 when it was implicated in the murder plot of a Ukrainian politician.
(a) Describe its geometry and state whether the molecule has a dipole moment. (b) How many pi bonds and sigma bonds are there in the molecule?

Bhumika Jayee

Numerade Educator

01:35

Problem 119

Write the electron configuration of the cyanide ion $\left(\mathrm{CN}^{-}\right) .$ Name a stable molecule that is isoelectronic with the ion.

Arpit Gupta

Numerade Educator

01:14

Problem 120

Carbon monoxide (CO) is a poisonous compound due to its ability to bind strongly to $\mathrm{Fe}^{2+}$ in the hemoglobin molecule. The molecular orbitals of CO have the same energy order as those of the $\mathrm{N}_{2} \mathrm{~mol}-$ ecule. (a) Draw a Lewis structure of $\mathrm{CO}$ and assign formal charges. Explain why CO has a rather small dipole moment of 0.12 D. (b) Compare the bond order of CO with that from molecular orbital theory.
(c) Which of the atoms (C or O) is more likely to form bonds with the $\mathrm{Fe}^{2+}$ ion in hemoglobin?

Anand Jangid

Numerade Educator

01:50

Problem 121

The geometries discussed in this chapter all lend themselves to fairly straightforward elucidation of bond angles. The exception is the tetrahedron, because its bond angles are hard to visualize. Consider the $\mathrm{CCl}_{4}$ molecule, which has a tetrahedral geometry and is nonpolar. By equating the bond moment of a particular $\mathrm{C}-\mathrm{Cl}$ bond to the resultant bond $\mathrm{mo}-$ ments of the other three $\mathrm{C}-\mathrm{Cl}$ bonds in opposite directions, show that the bond angles are all equal to $109.5^{\circ}$

Anand Jangid

Numerade Educator

01:08

Problem 122

Carbon suboxide $\left(\mathrm{C}_{3} \mathrm{O}_{2}\right)$ is a colorless pungentsmelling gas. Does it possess a dipole moment?

Bhumika Jayee

Numerade Educator

02:03

Problem 123

Which of the following ions possess a dipole moment: (a) $\mathrm{ClF}_{2}^{+},$ (b) $\mathrm{ClF}_{2}^{-},$ (c) $\mathrm{IF}_{4}^{+},$ (d) $\mathrm{IF}_{4}^{-} ?$

Susan Hallstrom

Numerade Educator

01:16

Problem 124

Given that the order of molecular orbitals for $\mathrm{NO}$ is similar to that for $\mathrm{O}_{2}$, arrange the following species in increasing bond orders: $\mathrm{NO}^{2-}, \mathrm{NO}^{-}, \mathrm{NO}, \mathrm{NO}^{+}$
$\mathrm{NO}^{2+}$

Anand Jangid

Numerade Educator

01:11

Problem 125

Shown here are molecular models of $\mathrm{SX}_{4}$ for $\mathrm{X}=\mathrm{F}$, $\mathrm{Cl},$ and $\mathrm{Br} .$ Comment on the trends in the bond angle between the axial $\mathrm{S}-\mathrm{X}$ bonds in these molecules.
$\mathrm{SF}_{4} \quad \mathrm{SCl}_{4} \quad \mathrm{SBr}_{4}$

Anand Jangid

Numerade Educator

01:07

Problem 126

Based on what you have learned from this chapter and Chapter $9,$ name a diatomic molecule that has the strongest known chemical bond and one with the weakest known chemical bond.

Anand Jangid

Numerade Educator

01:13

Problem 127

The stability of benzene is due to the fact that we can draw reasonable resonance structures for the molecule, which is equivalent to saying that there is electron delocalization. Resonance energy is a measure of how much more stable benzene is compared to the hypothetical molecule, which can be represented by just a single resonance structure. The enthalpies of hydrogenation (the addition of hydrogen) of cyclohexene $\left(\mathrm{C}_{6} \mathrm{H}_{10}\right)$ to cyclohexane $\left(\mathrm{C}_{6} \mathrm{H}_{12}\right)$ and benzene to cyclohexane are as follows:
(In these simplified structures, each point where lines meet represents a C atom. There is a H atom attached to a $s p^{2}$ -hybridized $\mathrm{C}$ atom and there are two $\mathrm{H}$ atoms attached to a $s p^{3}$ -hybridized $\mathrm{C}$ atom. . Estimate the resonance energy of benzene from these data.

Anand Jangid

Numerade Educator

02:54

Problem 128

How many carbon atoms are contained in one square centimeter of graphene? (See the Chemistry in Action essay "Buckyball, Anyone?" in Section 10.8 for a description of graphene.) What would be the mass of a $1-\mathrm{cm}^{2}$ section of graphene?

Anand Jangid

Numerade Educator