Chemistry Structure and Properties

Problem 6

What is the basic procedure for writing a covalent Lewis structure?

Mercedes Mazza

Numerade Educator

02:06

Problem 7

How do you determine the number of electrons that go into the Lewis structure of a molecule? A polyatomic ion?What are resonance structures? What is a resonance hybrid?

Madi Sousa

Numerade Educator

02:18

Problem 8

What are resonance structures? What is a resonance hybrid?

Mercedes Mazza

Numerade Educator

02:23

Problem 9

Do resonance structures always contribute equally to the overall
structure of a molecule? Explain.

Nadia Lara

Numerade Educator

04:41

Problem 10

What is formal charge? How is formal charge calculated? How is it
helpful?

Mercedes Mazza

Numerade Educator

Problem 11

Why does the octet rule have exceptions? Give the three major
categories of exceptions and an example of each.

Keenan Mintz

University of Miami

Problem 12

Why does the octet rule have exceptions? Give the three major categories of exceptions and an example of each.

Keenan Mintz

University of Miami

01:22

Problem 13

What is bond energy?

Keenan Mintz

University of Miami

01:03

Problem 14

Give some examples of some typical bond lengths. Which factors in-
fluence bond lengths?

Madi Sousa

Numerade Educator

00:59

Problem 15

Why is molecular geometry important? Cite some examples.

Rashmi Sinha

Numerade Educator

01:09

Problem 16

According to VSEPR theory, what determines the geometry of a molecule?

Eugene Schneider

University of Minnesota - Twin Cities

06:17

Problem 17

Name and draw the five basic electron geometries, and state the number of
electron groups corresponding to each. What constitutes an electron group?

Keenan Mintz

University of Miami

01:24

Problem 18

Explain the difference between electron geometry and molecular geometry. Under what circumstances are they not the same?

Eugene Schneider

University of Minnesota - Twin Cities

02:14

List the correct electron and molecular geometries that correspond to
each set of electron groups around the central atom of a molecule.
\begin{equation}\begin{array}{l}{\text { a. four electron groups overall; three bonding groups and one lone pair }} \\ {\text { b. four electron groups overall; two bonding groups and two lone pair }} \\ {\text { c. five electron groups overall; four bonding groups and one lone pair }} \\ {\text { d. five electron groups overall; three bonding groups and two lone pairs }}\end{array}\end{equation}\begin{equation}\begin{array}{l}{\text { e. five electron groups overall; two bonding groups and three lone pairs }} \\ {\text { f. sixe electron groups overall; five bonding groups and one lone pair }} \\ {\text { g. six electron groups overall; four bonding groups and two lone pairs }}\end{array}\end{equation}

Madi Sousa

Numerade Educator

Problem 20

How do you apply VSEPR theory to predict the shape of a molecule
with more than one interior atom?

Emily Himsel

Numerade Educator

02:17

Problem 21

How do you determine if a molecule is polar?

Keenan Mintz

University of Miami

01:09

Problem 22

Why is polarity a key connection between the structure of a molecule
and its properties?

Wilson Ma

The University of Alabama

01:59

Problem 23

Determine if a bond between each pair of atoms would be pure covalent, polar covalent, or ionic.
a. $\mathrm{Br}$ and $\mathrm{Br}$
b. $\mathrm{C}$ and $\mathrm{Cl}$
c. $\mathrm{C}$ and $\mathrm{S} \quad$
d. $\quad$ Sr and $\mathrm{O}$

Nadia Lara

Numerade Educator

02:36

Problem 24

Determine if a bond between each pair of atoms would be pure covalent, polar covalent, or ionic.
a. $\mathrm{C}$ and $\mathrm{N} \quad$ b. $\mathrm{N}$ and $\mathrm{S}$ c. $\mathrm{K}$ and $\mathrm{F} \quad$ d. $\quad \mathrm{N}$ and $\mathrm{N}$

Mercedes Mazza

Numerade Educator

02:48

Problem 25

Draw the Lewis structure for CO with an arrow representing the
dipole moment. Use Figure 6.5 to estimate the percent ionic character
of the CO bond.

Dr. Satish Ingale

Numerade Educator

01:08

Problem 26

Draw the Lewis structure for BrF with an arrow representing the dipole moment. Use Figure 6.5 to estimate the percent ionic character of the BrF bond.

Wilson Ma

The University of Alabama

05:35

Problem 27

Write the Lewis structure for each molecule.
a. PH $_{3} \quad$ b. $\mathrm{SCl}_{2} \quad$ c. HI $\quad$ d. $\mathrm{CH}_{4}$

Marjeta Wolfe

Numerade Educator

07:10

Problem 28

Write the Lewis structure for each molecule.
a. $\mathrm{NF}_{3} \quad$ b. HBr $\quad$ c. $\mathrm{SBr}_{2} \quad$ d. $\mathrm{CCl}_{4}$

Bryan Li

Numerade Educator

07:15

Problem 29

Write the Lewis structure for each molecule.
$\begin{array}{ll}{\text { a. } S F_{2}} & {\text { b. } \operatorname{SiH}_{4}} \\ {\text { c. HCOOH (both O bonded to } C )} & {\text { d. } C H_{3} S H(C \text { and } S \text { central) }}\end{array}$

Nadia Lara

Numerade Educator

07:42

Problem 30

Write the Lewis structure for each molecule.
a. $\mathrm{CH}_{2} \mathrm{O} \quad$ b. $\mathrm{C}_{2} \mathrm{Cl}_{4}$

Bryan Li

Numerade Educator

10:55

Problem 31

Write the Lewis structure for each molecule or ion.
a. $\mathrm{CI}_{4} \quad$ b. $\mathrm{N}_{2} \mathrm{O}$ $\mathrm{c} . \mathrm{SiH}_{4} \quad$ d. $\mathrm{Cl}_{2} \mathrm{CO}$

Bryan Li

Numerade Educator

04:28

Problem 32

Write the Lewis structure for each molecule or ion.
a. $\mathrm{H}_{3} \mathrm{COH} \quad$ b. $\mathrm{OH}^{-}$ c. $\mathrm{BrO}^{-} \quad$ d. $\mathrm{O}_{2}^{2-}$

Mercedes Mazza

Numerade Educator

09:37

Problem 33

Write the Lewis structure for each molecule or ion.
\begin{equation}\mathrm a.{N}_{2} \mathrm{H}_{2} \quad \text { b. } \mathrm{N}_{2} \mathrm{H}_{4}
\end{equation}\begin{equation} \mathrm c.{C}_{2} \mathrm{H}_{2} \quad \text { d. } \mathrm{C}_{2} \mathrm{H}_{4}\end{equation}

Nadia Lara

Numerade Educator

03:58

Problem 34

Write the Lewis structure for each molecule or ion.
\begin{equation}\mathrm a.{H}_{3} \mathrm{COCH}_{3} \text { b. } \mathrm{CN}^{-}\end{equation}\begin{equation}
\mathrm c.{NO}_{2}^{-} \quad \text { d. } \mathrm{ClO}^{-}\end{equation}

Mercedes Mazza

Numerade Educator

08:06

Problem 35

Write a Lewis structure that obeys the octet rule for each molecule or
ion. Include resonance structures if necessary and assign formal charges
to each atom.
\begin{equation}
\mathrm { a. } {SeO}_{2} \quad \text { b. } \mathrm{CO}_{3}^{2-} \quad \text { c. } \mathrm{ClO}^{-} \quad \text { d. } \mathrm{NO}_{2}^{-}
\end{equation}

Alexandra Grace

Numerade Educator

02:57

Problem 36

Write a Lewis structure that obeys the octet rule for each ion. Include
resonance structures if necessary and assign formal charges to each atom.
\begin{equation}\mathrm { a. }{ClO}_{3}^{-} \quad \text { b. } \mathrm{ClO}_{4}^{-} \quad \text { c. } \mathrm{NO}_{3}^{-} \quad \text { d. } \mathrm{NH}_{4}^{+}\end{equation}

Tiffany Noble

Numerade Educator

Problem 37

Use formal charge to determine which Lewis structure is better.

Andrew Eddins

Emory University

Problem 38

Use formal charge to determine which Lewis structure is better.

Andrew Eddins

Emory University

02:52

Problem 39

How important is this resonance structure to the overall structure of car-
bon dioxide? Explain.

Bryan Li

Numerade Educator

01:48

Problem 40

In $\mathrm{N}_{2} \mathrm{O},$ nitrogen is the central atom and the oxygen atom is terminal.
In $\mathrm{OF}_{2},$ however, oxygen is the central atom. Use formal charges to
explain why.

Tiffany Noble

Numerade Educator

04:14

Problem 41

Draw the Lewis structure (including resonance structures) for the acetate
ion $\left(\mathrm{CH}_{3} \mathrm{COO}^{-}\right) .$ For each resonance structure, assign formal charges to all atoms that have formal charge.

Nadia Lara

Numerade Educator

Problem 42

Draw the Lewis structure (including resonance structures) for methyl
azide $\left(\mathrm{CH}_{3} \mathrm{N}_{3}\right) .$ For each resonance structure, assign formal charges to all atoms that have formal charge.

Tiffany Noble

Numerade Educator

01:08

Problem 43

What are the formal charges of the atoms shown in red?

Nicole Krahulik

Numerade Educator

01:08

Problem 44

What are the formal charges of the atoms shown in red?

Nicole Krahulik

Numerade Educator

03:08

Problem 45

Write the Lewis structure for each molecule (octet rule not followed).
\begin{equation}\mathrm{ a.} {BCl}_{3} \quad \text { b. } \mathrm{NO}_{2} \quad \text { c. } \mathrm{BH}_{3}\end{equation}

Nadia Lara

Numerade Educator

01:39

Problem 46

Write the Lewis structure for each molecule (octet rule not followed).
\begin{equation}\mathrm { a. } {BBr}_{3} \quad \text { b. NO } \quad \text { c. } \mathrm{ClO}_{2}\end{equation}

Mercedes Mazza

Numerade Educator

08:10

Problem 47

Write the Lewis structure for each ion. Include resonance structures if
necessary and assign formal charges to all atoms. If necessary, expand
the octet on the central atom to lower formal charge.
\begin{equation}\mathrm{ a.} {PO}_{4}^{3-} \quad \text { b. } \mathrm{CN}^{-} \quad \text { c. } \mathrm{SO}_{3}^{2-} \quad \text { d. } \mathrm{ClO}_{2}^{-}\end{equation}

Lewis Rose

Numerade Educator

12:09

Problem 48

Write Lewis structures for each molecule or ion. Include resonance
structures if necessary and assign formal charges to all atoms. If you
need to, expand the octet on the central atom to lower formal charge.
\begin{equation}\mathrm{ a.} {SO}_{4}^{2-} \quad \text { b. } \mathrm{HSO}_{4}^{-} \quad \text { c. } \mathrm{SO}_{3} \quad \text { d. } \mathrm{BrO}_{2}^{-}\end{equation}

Bryan Li

Numerade Educator

09:51

Problem 49

Write Lewis structures for each molecule or ion. Use expanded octets as necessary.
\begin{equation}\begin{array}{lllll}{\text { a. } \mathrm{PF}_{5}} & {\text { b. } \mathrm{I}_{3}^{-}} & {\text { c. }} & {\mathrm{SF}_{4}} & {\text { d. GeF }_{4}}\end{array}\end{equation}

Bryan Li

Numerade Educator

11:04

Problem 50

Write Lewis structures for each molecule or ion. Use expanded octets
as necessary.
\begin{equation}\mathrm{ a. }{ClF}_{5} \quad \text { b. } \mathrm{AsF}_{6}-\quad \text { c. } \mathrm{Cl}_{3} \mathrm{PO} \quad \text { d. IF }_{5}\end{equation}

Bryan Li

Numerade Educator

02:12

Problem 51

Order these compounds in order of increasing carbon-carbon bond
strengtb and in order of decreasing carbon-carbon bond length:
HCCH, $\mathrm{H}_{2} \mathrm{CCH}_{2}, \mathrm{H}_{3} \mathrm{CCH}_{3}$

Bryan Li

Numerade Educator

Problem 52

Which of these compounds has the stronger nitrogen-nitrogen bond?
The shorter nitrogen-nitrogen bond?
$\mathrm{H}_{2} \mathrm{NNH}_{2}, \mathrm{HNNH}$

Bryan Li

Numerade Educator

02:06

Problem 53

A molecule with the formula AB3 has a trigonal pyramidal geometry.
How many electron groups are on the central atom (A)?

Arun Bana

Numerade Educator

03:24

Problem 54

A molecule with the formula AB3 has a trigonal planar geometry.
How many electron groups are on the central atom?

Shazia Naz

Numerade Educator

03:22

Problem 55

For each molecular geometry shown here, list the number of total elec-
tron groups, the number of bonding groups, and the number of lone

pairs on the central atom.

Bryan Li

Numerade Educator

02:38

Problem 56

For each molecular geometry shown here, list the number of total electron groups, the number of bonding groups, and the number of lone pairs on the central atom.

Kara Cecil

Numerade Educator

01:35

Problem 57

Determine the electron geometry, molecular geometry, and idealized
bond angles for each molecule. In which cases do you expect deviations
from the idealized bond angle?
\begin{equation}\mathrm{ a. } {PF}_{3} \quad \text { b. } \mathrm{SBr}_{2}\end{equation} \begin{equation}\mathrm{ c. }{CHCl}_{3} \quad \text { d. } \mathrm{CS}_{2}\end{equation}

Lottie Adams

Numerade Educator

03:03

Problem 58

Determine the electron geometry, molecular geometry, and idealized
bond angles for each molecule. In which cases do you expect deviations
from the idealized bond angle?
\begin{equation}\begin{array}{lllll}{\text { a. } \mathrm{CF}_{4}} & {\text { b. } \mathrm{NF}_{3}} & {\text { c. } \mathrm{OF}_{2}} & {\text { d. } \mathrm{H}_{2} \mathrm{S}}\end{array}\end{equation}

Madi Sousa

Numerade Educator

00:39

Problem 59

Which species has the smaller bond angle, $\mathrm{H}_{3} \mathrm{O}^{+}$ or $\mathrm{H}_{2} \mathrm{O}$ ? Explain.

Lottie Adams

Numerade Educator

05:03

Problem 60

Which species has the smaller bond angle, $\mathrm{ClO}_{4}^{-}$ or $\mathrm{ClO}_{3}^{-}$ or ? Explain.

Bryan Li

Numerade Educator

13:47

Problem 61

Determine the molecular geometry and draw each molecule or ion using
the bond conventions shown in the "Representing Molecular Geometries
on Paper"'section of this chapter (see Section 6.9$) .$
\begin{equation}\mathrm{ a. } {SF}_{4} \quad \text { b. } \mathrm{CIF}_{3} \quad \text { c. IF }_{2}^{-} \quad \text { d. IBr }_{4}^{-}\end{equation}

Aparna Shakti

Numerade Educator

02:47

Problem 62

Determine the molecular geometry and draw each molecule or ion, using
the bond conventions shown in the "Representing Molecular Geometries
on Paper" section of this chapter (see Section 6.9$) .$
a. $\mathrm{BrF}_{5} \quad$ b. $\mathrm{SCl}_{6}$ c. $\mathrm{PF}_{5} \quad$ d. IF $_{4}^{+}$

Madi Sousa

Numerade Educator

01:37

Problem 63

Determine the molecular geometry about each interior atom and draw
each molecule. (Skeletal structure is indicated in parentheses.)
\begin{equation}\begin{array}{l}{\text { a. } C_{2} \mathrm{H}_{2}(\mathrm{HCCH})} \\ {\text { b. } \mathrm{C}_{2} \mathrm{H}_{4}\left(\mathrm{H}_{2} \mathrm{CCH}_{2}\right)} \\ {\text { c. } \mathrm{C}_{2} \mathrm{H}_{6}\left(\mathrm{H}_{3} \mathrm{CCH}_{3}\right)}\end{array}
\end{equation}

Madi Sousa

Numerade Educator

01:30

Problem 64

Determine the molecular geometry about each interior atom and draw
each molecule. (Skeletal structure is indicated in parentheses.)
\begin{equation}\begin{array}{l}{\text { a. } \mathrm{N}_{2}} \\ {\text { b. } \mathrm{N}_{2} \mathrm{H}_{2}(\mathrm{HNNH})} \\ {\text { c. } \mathrm{N}_{2} \mathrm{H}_{4}\left(\mathrm{H}_{2} \mathrm{NN} \mathrm{H}_{2}\right)}\end{array}\end{equation}

Madi Sousa

Numerade Educator

Problem 65

Each ball-and-stick model shows the electron and molecular geometry of
a generic molecule. Explain what is wrong with each molecular geometry
and provide the correct molecular geometry, given the number of lone
pairs and bonding groups on the central atom.

Keenan Mintz

University of Miami

Problem 66

Keenan Mintz

University of Miami

Problem 67

Determine the geometry about each interior atom in each molecule
and draw the molecule. (Skeletal structure is indicated in parentheses.)
\begin{equation}\mathrm{a} . \mathrm{CH}_{3} \mathrm{OH}\left(\mathrm{H}_{3} \mathrm{COH}\right)
\end{equation} \begin{equation}\mathrm{ b. } {CH}_{3} \mathrm{OCH}_{3}\left(\mathrm{H}_{3} \mathrm{COCH}_{3}\right)
\end{equation} \begin{equation}\mathrm{c} . \mathrm{H}_{2} \mathrm{O}_{2}(\mathrm{HOOH})
\end{equation}

Madi Sousa

Numerade Educator

03:00

Problem 68

Determine the geometry about each interior atom in each molecule
and draw the molecule. (Skeletal structure is indicated in parentheses.)
\begin{equation}\mathrm{ a. }{CH}_{3} \mathrm{NH}_{2}\left(\mathrm{H}_{3} \mathrm{CNH}_{2}\right)\end{equation}
\begin{equation}\mathrm{ b. }{CH}_{3} \mathrm{CO}_{2} \mathrm{CH}_{3}\left(\mathrm{H}_{3} \mathrm{CCOOCH}_{3} \text { both } \mathrm{O} \text { atoms attached to second } \mathrm{C}\right)
\end{equation}\begin{equation}
\mathrm{ c. }{NH}_{2} \mathrm{CO}_{2} \mathrm{H}\left(\mathrm{H}_{2} \mathrm{NCOOH} \text { both } \mathrm{O} \text { atoms attached to } \mathrm{C}\right)
\end{equation}

Madi Sousa

Numerade Educator

01:16

Problem 69

Explain why $\mathrm{CO}_{2}$ and $\mathrm{CCl}_{4}$ are both nonpolar even though they contain
polar bonds.

Kara Cecil

Numerade Educator

01:22

Problem 70

$\mathrm{CH}_{3} \mathrm{F}$ is a polar molecule, even though the tetrahedral geometry often
leads to nonpolar molecules. Explain.

Eugene Schneider

University of Minnesota - Twin Cities

02:44

Problem 71

Determine whether each molecule in Exercise 57 is polar or nonpolar.

Wilson Ma

The University of Alabama

04:44

Problem 72

Determine whether each molecule in Exercise 58 is polar or nonpolar.

Keenan Mintz

University of Miami

Problem 73

Determine whether each molecule or ion is polar or nonpolar.
\begin{equation}\mathrm{ a. }{ClO}_{3}^{-} \quad \text { b. } \mathrm{SCl}_{2} \quad \text { c. } \mathrm{SCl}_{4} \quad\end{equation}

Madi Sousa

Numerade Educator

02:32

Problem 74

Determine whether each molecule is polar or nonpolar.
\begin{equation}\mathrm{ a. }{SiCl}_{4} \quad \text { b. } \mathrm{CF}_{2} \mathrm{Cl}_{2} \quad \text { c. SeF }_{6} \quad \text { d. IF }_{5}\end{equation}

Madi Sousa

Numerade Educator

03:34

Problem 75

Each compound contains both ionic and covalent bonds. Write ionic
Lewis structures for each, including the covalent structure for the ion
in brackets. Write resonance structures if necessary.
\begin{equation}\begin{array}{lllll}{\text { a. } \mathrm{BaCO}_{3}} & {\text { b. } \mathrm{Ca}(\mathrm{OH})_{2}} & {\text { c. } \mathrm{KNO}_{3}} & {\text { d. LiIO }}\end{array}\end{equation}

Madi Sousa

Numerade Educator

02:52

Problem 76

Each compound contains both ionic and covalent bonds. Write ionic
Lewis structures for each, including the covalent structure for the ion
in brackets. Write resonance structures if necessary.
\begin{equation}\mathrm{ a. }{RbIO}_{2} \quad \text { b. } \mathrm{NH}_{4} \mathrm{Cl} \quad \text { c. KOH } \quad \text { d. } \operatorname{Sr}(\mathrm{CN})_{2}\end{equation}

Madi Sousa

Numerade Educator

02:00

Problem 77

Carbon ring structures are common in organic chemistry. Draw a
Lewis structure for each carbon ring structure, including any necessary
resonance structures.
\begin{equation}\mathrm{ a. }{C}_{4} \mathrm{H}_{8} \quad \text { b. } \mathrm{C}_{4} \mathrm{H}_{4}
\end{equation}\begin{equation}\mathrm{ c. }{C}_{6} \mathrm{H}_{12} \quad \text { d. } \mathrm{C}_{6} \mathrm{H}_{6}
\end{equation}

Madi Sousa

Numerade Educator

00:50

Problem 78

Amino acids are the building blocks of proteins. The simplest amino
acid is glycine $\left(\mathrm{H}_{2} \mathrm{NCH}_{2} \mathrm{COOH}\right) .$ Draw a Lewis structure for glycine. $($Hint : The central atoms in the skeletal structure are nitrogen bonded to carbon, which is bonded to another carbon. The two oxygen atoms are bonded directly to the rightmost carbon atom.)

Madi Sousa

Numerade Educator

02:35

Problem 79

Formic acid is partly responsible for the sting of ant bites. By mass,
formic acid is $26.10 \% \mathrm{C}, 4.38 \% \mathrm{H},$ and 69.5$\%$ O.The molar mass of
formic acid is 46.02 $\mathrm{g} / \mathrm{mol} .$ Find the molecular formula of formic acid
and draw its Lewis structure.

Madi Sousa

Numerade Educator

Problem 80

Diazomethane is a highly poisonous, explosive compound because it
readily evolves $N_{2} .$ Diazomethane has the following composition by
mass: $28.57 \% \mathrm{C} ; 4.80 \% \mathrm{H} ;$ and 66.64$\% \mathrm{N}$ . The molar mass of diazomethane is 42.04 $\mathrm{g} / \mathrm{mol} .$ Find the molecular formula of diazometh-
ane, draw its Lewis structure, and assign formal charges to each atom.
Why is diazomethane not very stable? Explain.

Madi Sousa

Numerade Educator

Problem 81

Draw the Lewis structure for nitric acid (the hydrogen atom is attached to one of the oxygen atoms). Include all three resonance structures by alternating the double bond among the three oxygen atoms.
Use formal charge to determine which of the resonance structures is most important to the structure of nitric acid.

Nadia Lara

Numerade Educator

01:41

Problem 82

Phosgene $\left(\mathrm{Cl}_{2} \mathrm{CO}\right)$ is a poisonous gas that was used as a chemical
weapon during World War I. It is a potential agent for chemical terrorism today. Draw the Lewis structure of phosgene. Include all three resonance forms by alternating the double bond among the three terminal atoms. Which resonance structure is the best?

Tiffany Noble

Numerade Educator

02:58

Problem 83

The cyanate ion $\left(\mathrm{OCN}^{-}\right)$ and the fulminate ion $\left(\mathrm{CNO}^{-}\right)$ share the same three atoms, but have vastly different properties. The cyanate ion is stable, while the fulminate ion is unstable and forms explosive compounds. The resonance structures of the cyanate ion were explored in pounds. The resonance structures of the cyanate ion were explosive com
Example $6.6 .$ Draw Lewis structures for the fulminate ion-including possible resonance forms $-$ and use formal charge to explain why the fulminate ion is less stable (and therefore more reactive) than the cyanate ion.

Madi Sousa

Numerade Educator

03:20

Problem 84

Draw the Lewis structure for each organic compound from its condensed structural formula.
\begin{equation}\mathrm{a} \cdot \mathrm{C}_{3} \mathrm{H}_{8} \quad \text { b. } \mathrm{CH}_{3} \mathrm{OCH}_{3} \text { c. } \mathrm{CH}_{3} \mathrm{COCH}_{3}
\end{equation}\begin{equation}\mathrm{d} . \mathrm{CH}_{3} \mathrm{COOH} \quad \text { e. } \mathrm{CH}_{3} \mathrm{CHO}\end{equation}

Madi Sousa

Numerade Educator

03:00

Problem 85

Draw the Lewis structure for each organic compound from its condensed structural formula.
\begin{equation}\mathrm{ a. }{C}_{2} \mathrm{H}_{4} \quad \text { b. } \mathrm{CH}_{3} \mathrm{NH}_{2} \quad\mathrm{ c. }{HCHO}\end{equation}\begin{equation}
\mathrm{ d. }{CH}_{3} \mathrm{COOH} \text { e. } \mathrm{CH}_{3} \mathrm{CHO}
\end{equation}

Madi Sousa

Numerade Educator

01:45

Problem 86

Use Lewis structures to explain why $\mathrm{Br}_{3}^{-}$ and $\mathrm{I}_{3}^{-}$ are stable, while $\mathrm{F}_{3}^{-}$ is not.

Tiffany Noble

Numerade Educator

Problem 87

Draw the Lewis structure for $\mathrm{HCSNH}_{2} .$ (The carbon and nitrogen
atoms are bonded together, and the sulfur atom is bonded to the carbon atom.) Label each bond in the molecule as polar or nonpolar.

Stephanie Castillo

Numerade Educator

01:41

Problem 88

Draw the Lewis structure for urea, $\mathrm{H}_{2} \mathrm{NCONH}_{2},$ one of the compounds
responsible for the smell of urine. (The central carbon atom is bonded to
both nitrogen atoms and to the oxygen atom.) Does urea contain polar
bonds? Which bond in urea is most polar?

Tiffany Noble

Numerade Educator

02:11

Problem 89

Some theories of aging suggest that free radicals cause certain diseases and perhaps aging in general. As you know from the Lewis model, such molecules are not chemically stable and will quickly react with other molecules. According to some theories, free radicals may attack molecules within the cell, such as DNA, changing them and causing cancer or other diseases. Free radicals may also attack molecules on the surfaces of cells, making them appear foreign to the body's immune system. The immune system then attacks the cells and destroys them,weakening the body. Draw Lewis structures for the free radicals implicated in this theory of aging, which are given here.
\begin{equation}\mathrm{ a. }{O}_{2}^{-} \quad \text { b. } \mathrm{O}^{-} \quad \text { c. } \mathrm{OH}\end{equation}\begin{equation}\mathrm{d} . \mathrm{CH}_{3} \mathrm{OO} \quad \text(unpaired\ electron\ on\ terminal\ oxygen)
\end{equation}

Madi Sousa

Numerade Educator

01:24

Problem 90

Free radicals are important in many environmentally significant reactions. For example, photochemical smog-smog that results from the action of sunlight on air pollutants - forms in part by these two steps:
$$\begin{array}{c}{\mathrm{NO}_{2} \stackrel{\mathrm{UV} \text { light }}{\longrightarrow} \mathrm{NO}+\mathrm{O}} \\ {\mathrm{O}+\mathrm{O}_{2} \quad \longrightarrow \mathrm{O}_{3}}\end{array}$$
The product of this reaction, ozone, is a pollutant in the lower atmosphere. (Upper atmospheric ozone is a natural part of the atmosphere that protects life on Earth from ultraviolet light.) Ozone is an eye and lung irritant and also accelerates the weathering of rubber products. Rewrite the above reactions using the Lewis structure of each reactant and product. Identify the free radicals.

Madi Sousa

Numerade Educator

02:05

Problem 91

A compound composed of only carbon and hydrogen is 7.743$\%$ hydrogen by mass. Draw a Lewis structure for the compound.

Madi Sousa

Numerade Educator

02:16

Problem 92

A compound composed of only carbon and chlorine is 85.5$\%$ chlorine
by mass. Draw a Lewis structure for the compound.

Madi Sousa

Numerade Educator

13:37

Problem 93

Amino acids are biological compounds that link together to form proteins, the workhorse molecules in living organisms. The skeletal structures of several simple amino acids are shown here. For each skeletal structure,complete the Lewis structure, determine the geometry about each interior
atom, and draw the molecule, using the bond conventions of Section $6.9 .$

Keenan Mintz

University of Miami

05:37

Problem 94

The genetic code is based on four different bases with the structures
shown here. Assign a geometry to each interior atom in these four bases.
\begin{equation}\quad \text { a. cytosine } \quad \text { b. adenine } \quad \text { c. thymine } \quad \text { d. guanine }\quad\end{equation}

David Collins

Numerade Educator