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Organic Chemistry

Maitland Jones Jr., Steven A. Fleming

Chapter 1

Atoms and Molecules; Orbitals and Bonding - all with Video Answers

Educators

Chapter Questions

02:56

Problem 1

Explain why the two electrons in the $2 p_{x}$ orbital of carbon $\left({ }_{6} \mathrm{C}=1 s^{2} 2 s^{2} 2 p_{x}{ }^{2}\right)$ must have paired spins $(+1 / 2$ and $-1 / 2)$.

Susan Hallstrom
Susan Hallstrom
Numerade Educator
01:24

Problem 2

Explain why the fifth and sixth electrons in a carbon atom may not occupy the same orbital as long as they have parallel spins.

Lijeesh Krishnan
Lijeesh Krishnan
Numerade Educator
02:04

Problem 3

Write the electronic configurations for ${ }_{11} \mathrm{Na},{ }_{13} \mathrm{Al},{ }_{15} \mathrm{P},{ }_{16} \mathrm{~S}$, and ${ }_{18} \mathrm{Ar}$.

Suzanne W.
Suzanne W.
Numerade Educator
02:57

Problem 4

Show the direction of the dipole, if there is one, in the indicated bonds of the following molecules:
$$
\mathrm{H}-\mathrm{Cl}, \mathrm{H}-\mathrm{F}, \mathrm{Li}-\mathrm{CH}_{3}, \mathrm{H}_{3} \mathrm{C}-\mathrm{Cl}, \mathrm{HO}-\mathrm{NH}_{2}, \mathrm{H}_{3} \mathrm{C}-\mathrm{CH}_{3}
$$

Anthony Han
Anthony Han
Numerade Educator
01:12

Problem 5

Which of these two molecules has a dipole moment and which does not? Look carefully at the shapes of the two tetrahedral molecules. The blue dashed lines show the outlines of a tetrahedron. If visualizing the threedimensional aspects of these molecules is hard for you at first, by all means use molecular models.

Hast Aggarwal
Hast Aggarwal
Numerade Educator
01:15

Problem 6

Construct Lewis structures for the following neutral molecules:
*(a) $\mathrm{BF}_{3}$
(b) $\mathrm{H}_{2} \mathrm{Be}$
(c) $\mathrm{SiH}_{4}$
(d) $\mathrm{CH}_{2} \mathrm{Cl}_{2}$
(e) $\mathrm{HOCH}_{3}$
(f) $\mathrm{H}_{2} \mathrm{~N}-\mathrm{NH}_{2}$

Anand Jangid
Anand Jangid
Numerade Educator
02:48

Problem 7

Draw Lewis structures for the following neutral species. Use lines to indicate electrons in bonds and dots to indicate nonbonding electrons.
*(a) $\mathrm{CH}_{3}$
"(b) $\mathrm{CH}_{2}$
(c) $\mathrm{Br}$
(d) $\mathrm{OH}$
(e) $\mathrm{NH}_{2}$
(f) $\mathrm{H}_{3} \mathrm{C}-\mathrm{N}$

Susan Hallstrom
Susan Hallstrom
Numerade Educator
02:11

Problem 8

Each of the following compounds has at least one multiple bond. Draw a Lewis structure for each molecule. Use lines to indicate electrons in bonds and dots to indicate nonbonding electrons.
(a) $\mathrm{F}_{2} \mathrm{CCF}_{2}$
*(b) $\mathrm{H}_{3} \mathrm{CCN}$
(c) $\mathrm{H}_{2} \mathrm{CO}$
(d) $\mathrm{H}_{2} \mathrm{CCO}$
(e) $\mathrm{H}_{2} \mathrm{CCHCHCH}_{2}$
(f) $\mathrm{H}_{3} \mathrm{CNO}$
(g) $\mathrm{H}_{3} \mathrm{COCOH}$

Lottie Adams
Lottie Adams
Numerade Educator
04:18

Problem 9

Draw Lewis structures for the following charged species. In each case, the charge is shown closest to the charged atom.
(a) $-\mathrm{OH}$
(b) $-\mathrm{BH}_{4}$
(c) ${ }^{+} \mathrm{NH}_{4}$
(d) ${ }^{-} \mathrm{Cl}$
(e) ${ }^{+} \mathrm{CH}_{3}$
(f) ${ }^{+} \mathrm{OH}_{3}$
(g) ${ }^{+} \mathrm{NO}_{2}$

Freddie Montague
Freddie Montague
Numerade Educator
04:03

Problem 10

Add charges to the following compounds wherever necessary:
(a) : $\mathrm{CH}_{2}$
(b) $\cdot \mathrm{CH}_{3}$
(c) : $\dot{\mathrm{C} \mathrm{H}}$
(d) : $\ddot{\mathrm{O} \mathrm{H}}$
(e) : $\mathrm{OH}_{3}$
(f) $\mathrm{H}_{2} \mathrm{C}=\ddot{\mathrm{O}}$ :

Joshua Gibson
Joshua Gibson
Numerade Educator
11:59

Problem 11

Add electrons to complete the following Lewis structures. In each case, the charge is placed as close as possible to the charged atom.
(a) ${ }^{+} \mathrm{CH}_{2}$
(b) $-\mathrm{CH}_{2} \mathrm{CH}_{3}$
(c) $\mathrm{HC}=\mathrm{CH}_{2}$
(d) ${ }^{+} \mathrm{OH}_{3}$
(e) ${ }^{-} \mathrm{OH}$
(f) ${ }^{+} \mathrm{NH}_{2}$
(g) $-\mathrm{NH}_{2}$
(h) $\mathrm{CH}_{3}-\mathrm{C} \equiv \mathrm{N}-\mathrm{H}$

Bin Chen
Bin Chen
Numerade Educator
01:39

Problem 12

Draw a Lewis structure for nitric acid $\left(\mathrm{HO}-\mathrm{NO}_{2}\right)$, and verify that the nitrogen is positive and one of the oxygens is negative

Shahina -
Shahina -
Numerade Educator
01:39

Problem 13

Use the curved arrow formalism to convert your Lewis structure for nitric acid $\left(\mathrm{HO}-\mathrm{NO}_{2}\right.$, Problem $\left.1.12\right)$ into a resonance form.

Lottie Adams
Lottie Adams
Numerade Educator
02:31

Problem 14

Draw another structure for nitromethane in which every atom is neutral. Hint: There are only single bonds in this structure.

Sam Limsuwannarot
Sam Limsuwannarot
Numerade Educator
03:03

Problem 15

Acetone, $\left(\mathrm{CH}_{3}\right)_{2} \mathrm{CO}$, is similar to formaldehyde. Draw a Lewis structure for acetone. Draw two resonance forms. Which do you suppose contributes more to the molecule? Why? Which contributes less? Why?

Nicole Smina
Nicole Smina
Numerade Educator
04:41

Problem 16

Use the arrow formalism to convert each of the following Lewis structures into another resonance form. Notice that part (e) of this question asks you to do something new-to move electrons one at a time in writing Lewis forms.

Freddie Montague
Freddie Montague
Numerade Educator
03:34

Problem 17

Use the arrow formalism to write resonance forms that contribute to the structures of the following molecules:

Ronald Prasad
Ronald Prasad
Numerade Educator
01:28

Problem 18

Write two more resonance forms for 1,3 -butadiene.

Lottie Adams
Lottie Adams
Numerade Educator
02:31

Problem 19

Add dots for the electron pairs and write resonance forms for the following structures:

Sam Limsuwannarot
Sam Limsuwannarot
Numerade Educator
04:52

Problem 20

Write Lewis structures and resonance forms for the following compounds. If you have problems visualizing the structures of some of these molecules, see the inside front cover of this book.
(a) $\mathrm{NCCH}_{2}^{-}$
(b) ${ }^{-} \mathrm{OSO}_{2} \mathrm{OH}$
(c) $\mathrm{CH}_{3} \mathrm{COO}^{-}$

David Collins
David Collins
Numerade Educator
03:24

Problem 21

Which of the following pairs of structures are not resonance forms of each other? Why not? You may have to add dots to make good Lewis structures first.

Bobby Barnes
Bobby Barnes
University of North Texas
07:51

Problem 22

In the following pairs of resonance forms, indicate which form you think is more important and therefore contributes more to the structure. Justify your choice. You may have to add dots to make good Lewis structures first.

Anupa Sharad Medhekar
Anupa Sharad Medhekar
Numerade Educator
01:32

Problem 23

What is the simplest molecule? If $\mathrm{H}_{2}$ is the second simplest molecule, the answer to this question must be "H $_{2}$ minus something." What might the "something" be? The answer will appear farther along in the text, so think about this question for a while now.

David Collins
David Collins
Numerade Educator
01:44

Problem 24

Sketch the orbitals produced through the interaction of a carbon $2 s$ atomic orbital overlapping end-on with a carbon $2 p$ atomic orbital.

Nicole Smina
Nicole Smina
Numerade Educator
06:57

Problem 25

The bond between two fluorine atoms in $\mathrm{F}_{2}$ can be viewed as resulting from the end-on interaction between the $2 p_{y}$ orbital on each fluorine. Sketch the molecular orbitals produced through the interaction of two fluorine $2 p_{y}$ atomic orbitals.

Shahina -
Shahina -
Numerade Educator
02:12

Problem 26

Contrast the interactions between two $2 p$ orbitals approaching in the two different ways shown below.

Lottie Adams
Lottie Adams
Numerade Educator
02:45

Problem 27

Sketch the profile of an endothermic reaction. See Figure $1.45$ for the sketch of an exothermic reaction.

Adriano Chikande
Adriano Chikande
Numerade Educator
03:16

Problem 28

Notice in Table $1.10$ that the $\mathrm{C}-\mathrm{H}$ bond is about the same strength as the $\mathrm{C}$ - $\mathrm{F}$ bond. Organic chemists use this fact in design of pharmaceutical drugs, many of which have $\mathrm{C}-\mathrm{F}$ groups. The fluorine has about the same size and has a similar bond strength to carbon as does an H. What other attributes might an F bring to a drug?

Lottie Adams
Lottie Adams
Numerade Educator
00:42

Problem 29

Although our guess of $52 \mathrm{kcal} / \mathrm{mol}$ is quite close to the actual value, it is a bit low. In other words, the $\mathrm{H}_{2}{ }^{+}$molecule is more stable (lower in energy) than we thought. Why is our estimate of bond strength a little low? To ask the same question another way, why might the stabilization of two electrons in an orbital be less than twice the stabilization of one electron in the orbital?

Nicole Smina
Nicole Smina
Numerade Educator
02:33

Problem 30

Draw the orbital interaction diagram for $\mathrm{He}_{2}{ }^{+}$.

Kyle Gassaway
Kyle Gassaway
Numerade Educator
01:16

Problem 31

Estimate the bond strength for $\mathrm{He}_{2}{ }^{+}$.
Show how you arrived at your estimate.

Matthew Lueckheide
Matthew Lueckheide
Numerade Educator
01:05

Problem 32

Use the answer to Problem $1.29$ to work out the answer to a more subtle question. In $\mathrm{He}_{2}$, both the bonding and the antibonding molecular orbitals are filled with two electrons. Consider electron-electron repulsion to explain why the stabilization of the two electrons in $\Phi_{B}$ is less than the destabilization of the electrons in $\Phi_{A}$.

David Collins
David Collins
Numerade Educator
00:59

Problem 33

Identify the Lewis base (nucleophile) and Lewis acid (electrophile) in each of these reactions. Write the molecule formed in each case.
(a) $\mathrm{H}^{+} \quad \mathrm{H}:^{-} \rightarrow$ ?
(b) $\mathrm{H}^{+}$
(c) $\mathrm{H}_{3} \mathrm{C}^{+} \quad{ }^{-}: \mathrm{CH}_{3} \rightarrow$ ?
(d) $\mathrm{H}_{3} \mathrm{C}^{+} \quad \because O ? \mathrm{H} \rightarrow$ ?

Stephen Ho
Stephen Ho
Numerade Educator
02:38

Problem 34

Here is a chance to practice your electron pushing. Draw curved arrow formalisms for all the reactions in Problem $1.33 .$

Himanshu Kushwaha
Himanshu Kushwaha
Numerade Educator
04:01

Problem 35

Draw Lewis dot structures for the following compounds:
(a) $\mathrm{CH}_{3} \mathrm{NO}_{2}$ (nitromethane, used for fuel in stock car racing)
(b) $\mathrm{CH}_{2}=\mathrm{CHCl}$ (vinyl chloride used to make polyvinyl chloride, also known as PVC)
(c) $\mathrm{CH}_{3} \mathrm{CO}_{2} \mathrm{H}$ (acetic acid, the acid in vinegar)
(d) $\mathrm{HOSO}_{2} \mathrm{OH}$ (sulfuric acid, $\mathrm{H}_{2} \mathrm{SO}_{4}$, the world's most widely used industrial chemical)
See the inside front cover for structures, if you don't know them.

Freddie Montague
Freddie Montague
Numerade Educator
View

Problem 36

Draw two resonance structures for each of the compounds in the previous problem. Show the arrow formalism for interconversion of the resonance forms for each compound.

Vipin Singh
Vipin Singh
Numerade Educator
00:34

Problem 37

Use the arrow formalism to write structures for the resonance forms contributing to the structures of the following ions:

Nicole Smina
Nicole Smina
Numerade Educator
01:10

Problem 38

Use the arrow formalism to draw three additional resonance structures for each of the following molecules:

Amy Jiang
Amy Jiang
Numerade Educator
09:58

Problem 39

Draw three resonance structures for each of the following:
(a) ${ }^{-} \mathrm{CH}_{2} \mathrm{NO}_{2}$
(b) $\mathrm{CH}_{3} \mathrm{CO}_{2} \mathrm{CH}_{3}$
(c) ${ }^{-} \mathrm{CH}_{2} \mathrm{CO}_{2}{ }^{-}$
(d) $\mathrm{HOSO}_{2} \mathrm{O}^{-}$

Shalini Tyagi
Shalini Tyagi
Numerade Educator
00:58

Problem 40

The curved arrow formalisms shown in this problem are wrong. Redraw them correctly.

Aadit Sharma
Aadit Sharma
Numerade Educator
06:19

Problem 41

Add the arrows to the following equilibria:

Temi Ajayi
Temi Ajayi
Numerade Educator
02:15

Problem 42

Draw resonance forms for the following cyclic molecules:

Amy Jiang
Amy Jiang
Numerade Educator
02:15

Problem 43

Draw resonance forms for the following acyclic molecules:

Amy Jiang
Amy Jiang
Numerade Educator
02:54

Problem 44

Ozone $\left(\mathrm{O}_{3}\right)$ resembles the molecules in Problem $1.38$. These days it has a rather bad press, as it is present in too small an amount in the stratosphere and too great an amount in cities. Write a Lewis "dot" structure for ozone and sketch out contributing resonance forms. Write one neutral resonance form. Be careful with this last part, the answer is tricky.

Ian Lee
Ian Lee
Numerade Educator
View

Problem 45

Draw two resonance structures for each of the compounds shown below.

Vipin Singh
Vipin Singh
Numerade Educator
02:23

Problem 46

Show the curved arrow formalisms for interconverting the forms you drew in Problem $1.45 .$

Henry R
Henry R
Numerade Educator
01:37

Problem 47

Which "resonance structure" (b or c) does not contribute to the molecule $\mathrm{CH}_{3} \mathrm{NOC} \mathrm{C}_{2}$ (a)? Why doesn't it contribute?

Freddie Montague
Freddie Montague
Numerade Educator
01:42

Problem 48

Add charges to the following molecules where necessary:

Sam Limsuwannarot
Sam Limsuwannarot
Numerade Educator
01:42

Problem 49

Add charges to the following molecules where necessary:

Sam Limsuwannarot
Sam Limsuwannarot
Numerade Educator
01:38

Problem 50

Determine the formal charge, if there is one, for each of the nitrogens in the following molecules:

Lottie Adams
Lottie Adams
Numerade Educator
01:42

Problem 51

Determine the formal charges, if any, for the molecules shown below.

Sam Limsuwannarot
Sam Limsuwannarot
Numerade Educator
02:40

Problem 52

Write Lewis dot structures for the neutral diatomic molecules $\mathrm{F}_{2}$ and $\mathrm{N}_{2}$. In $\mathrm{F}_{2}$, there is a single bond between the two atoms, but in $\mathrm{N}_{2}$ there is a triple bond between the two atoms.

Dr. Satish Ingale
Dr. Satish Ingale
Numerade Educator
04:20

Problem 53

Atomic carbon can exist in several electronic states, one of which is (of course) lowest in energy and is called the "ground state." Write the electronic description for the ground state and at least two higher-energy, "excited states."

Guilherme Barros
Guilherme Barros
Numerade Educator
05:43

Problem 54

Write the electronic configurations for the following ions:
(a) $\mathrm{Na}^{+}$
(b) $\mathrm{F}^{-}$
(c) $\mathrm{Ca}^{2+}$

Daniel Kyinakwa
Daniel Kyinakwa
Numerade Educator
06:26

Problem 55

Write the electronic configurations for the atoms in the fourth row of the periodic table, ${ }_{19} \mathrm{~K}$ through ${ }_{36} \mathrm{Kr}$.

Arpit Gupta
Arpit Gupta
Numerade Educator
06:26

Problem 56

Write electronic configurations for the valence electrons of ${ }_{14} \mathrm{Si},{ }_{15} \mathrm{P}$, and ${ }_{16} \mathrm{~S}$. Indicate the spins of the electrons in the $3 p$ orbitals with a small up or down arrow.

Arpit Gupta
Arpit Gupta
Numerade Educator
00:23

Problem 57

There is an instrument, called an electron spin resonance (ESR) spectrometer, that can detect "unpaired spin." In which of the following species would the ESR machine find unpaired spin? Explain.
(a) $\mathrm{O}$
(b) $\mathrm{O}^{+}$
(c) $\mathrm{O}^{2-}$
(d) $\mathrm{Ne}^{+}$
(e) $\mathrm{F}^{-}$

Jorge Villanueva
Jorge Villanueva
Numerade Educator
01:57

Problem 58

For the Lewis structure of carbon monoxide shown below, first verify that both the carbon and the oxygen atoms are neutral.

Second, indicate the direction of the dipole moment in this Lewis structure:
$$
: \mathrm{C}=\ddot{\mathrm{O}}:
$$
As you have just shown, on the basis of this Lewis structure carbon monoxide should have a substantial dipole moment. In fact, the experimentally determined dipole moment is very small, $0.11 \mathrm{D}$. Draw a second resonance structure for carbon monoxide, verify the presence of any charges, and indicate the direction of any dipole in this second resonance form. Finally, rationalize the observation of only a very small dipole moment in carbon monoxide.

Lottie Adams
Lottie Adams
Numerade Educator
01:04

Problem 59

Would you expect formaldehyde, shown below, to have a greater dipole moment than carbon monoxide (see Problem 1.58)? Why or why not?

Madi Sousa
Madi Sousa
Numerade Educator
03:40

Problem 60

Consider three possible structures for methylene fluoride $\left(\mathrm{CH}_{2} \mathrm{~F}_{2}\right)$, one tetrahedral (structure $\mathbf{A}$ ), the others flat (structures $\mathbf{B}$ and $\mathbf{C}$ ). Does the observation of a dipole moment in $\mathrm{CH}_{2} \mathrm{~F}_{2}$ allow you to decide between structures $\mathbf{A}$ and $\mathbf{B}$ ? What about structures $\mathbf{A}$ and $\mathbf{C}$ ?

Heath Mclean
Heath Mclean
Numerade Educator
02:02

Problem 61

Draw the arrow formalism for the homolytic cleavage of $\mathrm{Br}_{2}$. Draw the arrow formalism for the heterolytic cleavage of $\mathrm{Br}_{2}$.

Amy Jiang
Amy Jiang
Numerade Educator
07:15

Problem 62

While wandering in an alternative universe, you find yourself in a chemistry class and, quite naturally,

Dr. Satish Ingale
Dr. Satish Ingale
Numerade Educator
04:28

Problem 63

Indicate whether the following reactions are exothermic or endothermic. Estimate by how much. Use Table $1.10$ (p. 40 ) and $66 \mathrm{kcal} / \mathrm{mol}$ for the "double" part of $\mathrm{C}=\mathrm{C}$.

Carolina Acevedo
Carolina Acevedo
Numerade Educator
02:24

Problem 64

Let's extend our discussion of $\mathrm{H}-\mathrm{H}$ a little bit to make the orbitals for the molecule linear $\mathrm{HHH}$. Use the molecular orbitals for $\mathrm{H}_{2}$ and the $1 s$ atomic orbital of H. Place the new $\mathrm{H}$ in between the two hydrogen atoms of $\mathrm{H}-\mathrm{H}$. Watch out for net-zero (orthogonal) interactions!

Himanshu Kushwaha
Himanshu Kushwaha
Numerade Educator
08:13

Problem 65

Make a set of molecular orbitals very much like the ones you made for linear $\mathrm{HHH}$ in Problem $1.64$, but this time use $2 p$ orbitals, not 1 s orbitals. Place one $2 p$ orbital between the other two. Use the molecular orbitals $2 p+2 p$ and $2 p-2 p$ that you constructed in Problem $1.26$. Order the new orbitals in energy.

Luz Esteban-Torres
Luz Esteban-Torres
Numerade Educator
07:18

Problem 66

One can generate the molecular orbitals for triangular $\mathrm{H}_{3}$ simply by bending the orbitals generated in Problem $1.64$ to transform the linear molecule into the bent one.
(a) Bend the three molecular orbitals for $\mathrm{HHH}$ to make the orbitals for the triangle. Make careful drawings. Note that as the old $\mathrm{H}(1)$ and $\mathrm{H}(3)$ come closer together in the triangle, they will create a new bonding or antibonding interaction.
(b) Order the new molecular orbitals in energy by counting the nodes.
(c) Which will be lower in energy, linear or triangular $\mathrm{H}_{3}{ }^{+}$? What a sophisticated question! Yet, given the answer to Problems $1.64$ and $1.65$, it is easy.

Zubair Abdulla
Zubair Abdulla
Numerade Educator
02:34

Problem 67

In the chapter, we made the two molecular orbitals for $\mathrm{H}_{2}$ (p. 35 ), and in Problem $1.64$ we used the two molecular orbitals of $\mathrm{H}_{2}$ and a 1 s orbital to make HHH. This time, generate the molecular orbitals for $\mathrm{HHHH}$, linear $\mathrm{H}_{4}$, from the molecular orbitals of two $\mathrm{H}_{2}$ molecules placed end to end. Remember. At this level of "theory," you need only interact orbitals closest in energy.
Order the new molecular orbitals in energy by counting the nodes, and place the proper number of electrons in the orbitals.

ES
Eugene Schneider
University of Minnesota - Twin Cities
08:13

Problem 68

Make the molecular orbitals for square $\mathrm{H}_{4}$ by allowing the molecular orbitals of $\mathrm{H}_{2}$ to interact as shown below:
Order the new molecular orbitals by counting the nodes, and add the proper number of electrons. You might check your answer by deriving the same orbitals. Do this by bending the molecular orbitals for linear HHHH developed in Problem 1.67.

Luz Esteban-Torres
Luz Esteban-Torres
Numerade Educator
01:35

Problem 69

Choose the reaction titled "Unimolecular nucleophilic substitution" and click on the Play button. Do you suppose the first step of this reaction is a homolytic or a heterolytic cleavage? Observe the Highest Occupied Molecular Orbital (HOMO) track by clicking on the HOMO button. The location (orbital) of the most available electrons will be shown throughout the reaction. Notice that the electron density goes with the bromine as it comes off. That should help you answer this question.

Grigoriy Sereda
Grigoriy Sereda
Numerade Educator
01:30

Problem 70

Choose the "Introduction" on the bottom left of the Table of Contents page. Read this short document. Under the "Technical Issues" heading there is a discussion of solvent effects. After reading this section, how do you think use of a polar solvent in the "Unimolecular nucleophilic substitution" reaction might affect the answer to the previous question? That is, would a polar solvent have more impact on a homolytic or a heterolytic cleavage?

David Collins
David Collins
Numerade Educator
11:54

Problem 71

Choose the reaction "Alkene hydrohalogenation" and observe the molecule that initially comes to the screen. It has a carbon-carbon double bond. Click on the HOMO button. Observe the calculated area for the $\pi$ bond that is shown to answer the following questions. Is the electron density of a $\pi$ bond constrained to the space between the carbons? Do you suppose the $\pi$ bond electrons are held more or less tightly than $\sigma$ bond electrons?

Ian Kaigh
Ian Kaigh
Numerade Educator