21 Organic Compounds
Y
ou may not see it, but carbon
is everywhere. It is in your
clothes, your backpack, your
books, and your food. It is even in
you. Carbon is an amazing element.
In this chapter, you will learn how
carbon can form more than 16 million
known compounds. Also, you will see
how black, gooey petroleum is transformed into useful substances. You
will be introduced to some carbon
compounds essential to life itself—
among them proteins and DNA.
What do you think?
Science Journal Look at the picture
below with a classmate. Discuss what
this might be. Here’s a hint: This pattern offers an infinite variety of forms.
Write your answer or best guess in
your Science Journal.
638
he element carbon exists in three very different
forms. It exists as dull, black charcoal; slippery,
gray graphite; and bright, sparkling diamond. However, this is nothing compared with the millions of
different compounds that carbon can form. In this
activity, you will seek out the carbon hidden in two
common substances.
WARNING: Always use extreme caution
around an open flame. Point test tubes
away from yourself and others.
EXPLORE T
ACTIVITY
Identify a common element
1. Place a small piece of bread in a test tube.
2. Using a test-tube holder, hold the tube
over the flame of a laboratory burner
until you observe changes in the bread.
3. Using a clean test tube and a small amount
of paper instead of bread, repeat step 2.
Observe
1. What happened when you heated the tubes? Did you see anything leave
the two samples?
2. What remained in each of the test tubes? Describe it in your Science
Journal. What do you think it is?
FOLDABLES
Reading &Study
& Study
Skills
Making a Vocabulary Study Fold Make the
following vocabulary Foldable to ensure you
have understood the content by defining the
vocabulary terms from this chapter.
1. Place a sheet of notebook paper in front of you so the short
side is at the top. Fold the paper in half from the left side to the
right side.
2. Through the top thickness of paper, cut along every third line from
the outside edge to the centerfold, forming ten tabs, as shown.
3. On the front of each tab, write a vocabulary word listed on the first
page of each section in this chapter. On the back of each tab, define
the word.
639
SECTION
Simple Organic
Compounds
Organic Compounds
■
Identify the difference between
organic and inorganic carbon
compounds.
■ Examine the structures of some
organic compounds.
■ Differentiate between saturated
and unsaturated hydrocarbons.
■ Identify isomers of organic
compounds.
Vocabulary
organic compound
hydrocarbon
saturated hydrocarbon
isomer
unsaturated hydrocarbon
What do you have in common with your athletic shoes, sunglasses, and backpack? All the items shown in Figure 1 contain
compounds of the element carbon—and so do you. Most compounds containing the element carbon are organic compounds.
At one time, scientists thought that only living organisms
could make organic compounds, which is how they got their
name. Did you notice the similarity between the terms organic
and organism? By 1830, scientists could make organic compounds in laboratories, but they continued to call them organic.
Of the millions of carbon compounds known today, more
than 90 percent of them are considered organic. The other ten
percent, including carbon dioxide and the carbonates, are
considered inorganic compounds because they are found in
nonliving things, such as air, rocks, and minerals.
Bonding You may wonder why carbon can form so many
Carbon compounds surround you—
they’re in your food, your body, and
most materials you use every day.
organic compounds. The main reason is that a carbon atom
has four electrons in its outer energy level. This means that each
carbon atom can form four covalent bonds with atoms of
carbon or with other elements. As you have learned, a covalent
bond is formed when two atoms share a pair of electrons. Four
is a large number of bonds compared to the number of bonds
that atoms of other elements can form.
This allows carbon to form many
types of compounds ranging from
small compounds used as fuel, to
complex compounds found in medicines and dyes, and the polymers used
in plastics and textile fibers.
Figure 1
Most items used every day
contain carbon.
640
CHAPTER 21 Organic Compounds
Arrangement Another reason carbon can form so many
Figure 2
compounds is that carbon can link together with other carbon
atoms in many different arrangements—chains, branched
chains, and even rings. It also can form double and triple bonds
as well as single bonds. In addition, carbon can bond with atoms
of many other elements, such as hydrogen and oxygen. Figure 2
shows some possible arrangements for carbon compounds.
Carbon atoms bond to form
chains, as in heptane found in
gasoline.
The chains can be
branched, as in isoprene, found
in natural rubber.
The chains
also can be rings, as in vanillin,
found in vanilla flavor.
Hydrocarbons
H
H
— —
— —
— —
H
— —
H
— —
H
— —
H
— —
H
H
H
H
H
H
H
H
H—C—C—C—C—C—C—C—H
—
H
H—C—H
H
H
—
C—C—C—C
H
H
H
OH
—
H
C
C—
—
H
C
— —
C
C— C
—
H
H
O—C—H
—
Carbon forms an enormous number of compounds with
hydrogen alone. A compound made up of only carbon and
hydrogen atoms is called a hydrocarbon. Does the furnace,
stove, or water heater in your home burn natural gas? A main
component of the natural gas used for these purposes is the hydrocarbon methane. The chemical formula of methane is CH4.
Methane can be represented in two other ways, as shown in
Figure 3A. The structural formula shows that four hydrogen
atoms are bonded to one carbon atom in a methane molecule.
Each line between atoms represents a single covalent bond. The
space-filling model in Figure 3A shows a more realistic picture of
the size and arrangement of the atoms in the molecule.
Chemists might refer to space saving models occasionally, but
use chemical and structural formulas to write about reactions.
Another hydrocarbon used as fuel is propane. Some stoves,
most outdoor grills, and the heaters in hot-air balloons burn this
hydrocarbon, which is found in bottled gas. Propane’s structural
formula and space-filling model are shown in Figure 3B.
Methane and other hydrocarbons produce more than
90 percent of the energy humans use. Carbon compounds also
are important in medicines, foods, and clothing. To understand
how carbon can play so many roles, you must understand how it
forms bonds.
C—
H
H
O
Figure 3
Natural gas is mostly
Bottled gas is
methane, CH4.
mostly propane, C3H8.
—HH
HH——CC—
H
—
—
—
H — C— C— C— H
HH
Methane
CH4
—
—
—
— —
—
H H
—
HH
H H
H
Propane
C3H8
SECTION 1 Simple Organic Compounds
641
Single Bonds
Table 1 Some Hydrocarbons
Methane
Chemical
Formula
In some hydrocarbons, the carbon atoms
are joined by single covalent bonds. Hydrocarbons containing only single-bonded carbon atoms are called saturated hydrocarbons.
Saturated means that a compound holds as
many hydrogen atoms as possible—it is saturated with hydrogen atoms.
Structural
Formula
H
CH4
— —
Name
H—C—H
H
— —
— —
H
H
Table 1 lists four saturated hydrocarbons.
Notice how each carbon atom appears to be a
link in a chain connected by single covalent
bonds. Figure 4 shows a graph of the boiling
points of some hydrocarbons. Notice the relationship between boiling points and the addition of carbon atoms.
— —
— —
H
— —
H
H
H
H
H—C—C—C—H
H
H
H
H
— —
C4H10
H
What are saturated
hydrocarbons?
H—C—C—H
— —
Butane
C3H8
H
H
— —
Propane
C2H6
— —
Ethane
H
H H
H
H—C—C—C—C—H
Structural Isomers Perhaps you have seen or know about
butane, which is a gas that sometimes is burned in camping
stoves and lighters. The chemical formula of butane is C4H10.
Another hydrocarbon called isobutane has exactly the same
chemical formula. How can this be? The answer lies in the
arrangement of the four carbon atoms. Look at Figure 5. In a
molecule of butane, the carbon atoms form a continuous chain.
The carbon chain of isobutane is branched. The arrangement of
carbon atoms in each compound changes the shape of the molecule. Isobutane and butane are isomers.
Figure 4
Boiling Points of Hydrocarbons
50
Pentane
0
Boiling point (°C)
Boiling points of hydrocarbons
increase as the number of carbon atoms in the chain
increases.
Butane
Propane
–50
Ethane
–100
–150
Methane
–200
0
642
CHAPTER 21 Organic Compounds
1
2
3
4
Number of carbon atoms in chain
5
6
Figure 5
Butane has two
isomers.
One isomer
has a straight chain.
The other isomer has
a branched chain.
—
H
H — C— C— C— H
—
—
H
———
—
H
—
—
—
H H
—
H H
H — C— C— C— C— H
—
H
—
H
—
—
—
H H
H
H
H— C— H
—
Butane
C4H10
Isobutane
C4H10
H
Isomers are compounds that have identical chemical formulas but different molecular structures and shapes. Thousands of
isomers exist among the hydrocarbons. Generally, melting
points and boiling points decrease as the amount of branching
in an isomer increases. You can see this pattern in Table 2, which
lists properties of butane and isobutane.
Sometimes properties of isomers can vary amazingly. For
example, the isomer of octane having all eight carbons in a
straight chain melts at ⫺56.8°C, but the most branched octane
melts at 100.7°C. In this case, the high melting point results
from the symmetry of the molecule and its globular shape. Look
for this isomer when you do the Try at Home MiniLAB.
Other Isomers There are many other kinds of isomers in
organic and inorganic chemistry. Some isomers differ only
slightly in how their atoms are arranged in space. Such isomers
form what is often called right- and left-handed molecules, like
mirror images. Two such isomers may have nearly identical
physical and chemical properties.
Table 2 Properties of Butane Isomers
Property
Butane
Isobutane
Description
Colorless gas
Colorless gas
0.60 kg/L
0.603 kg/L
Melting Point
–135°C
–145°C
Boiling Point
–0.5°C
–10.2°C
Density
Modeling Structures
of Octane
Procedure
1. To model octane, C8H18, a
hydrocarbon found in gasoline, use soft gumdrops to
represent carbon atoms.
2. Use raisins to represent
hydrogen atoms.
3. Use toothpicks for
chemical bonds.
WARNING: NEVER eat any
food in the laboratory.
Analysis
1. How do you distinguish one
structure from another?
2. What was the total number
of different molecules found
in your class?
SECTION 1 Simple Organic Compounds
643
Multiple Bonds
H—C—
—C—H
H
H
Peaches are among the many fruits that can form
small quantities of ethylene gas, which aids in ripening. Ethylene is another name for the hydrocarbon
ethene, C2H4. This contains one double bond in
which two carbon atoms share two pairs of electrons.
The hydrocarbon ethyne contains a triple bond in
which three pairs of electrons are shared. Hydrocarbons, such as ethene and ethyne, that contain at least
one double or triple bond are called unsaturated
hydrocarbons. They are shown in Figure 6.
C—C
H
What is another name for
ethene?
H
Figure 6
Hydrocarbons can contain double
or triple bonds between carbon
atoms.
Ethyne, also called
acetylene, is used in torches for
welding.
Ethene or ethylene
gas ripens fruit.
Section
Remember that saturated hydrocarbons contain only single bonds and
have as many hydrogen atoms as possible. Hydrocarbons having more than
one double or triple bond are called
polyunsaturated, because the prefix poly
means many.
Assessment
1. Explain why carbon can form so many
organic compounds?
2. Compare and contrast ethane, ethene,
and ethyne.
3. How is an unsaturated hydrocarbon
different from a saturated hydrocarbon?
4. How did organic compounds get
this name?
5. Think Critically Cyclopropane is a saturated hydrocarbon containing three carbon
atoms. In this compound, each carbon atom
is bonded to two other carbon atoms. Draw
its structural formula. Are cyclopropane and
propane isomers? Explain. Carbon can form
single, double, and triple bonds easily. How
many electrons are shared between two carbon atoms joined in a triple bond?
644
CHAPTER 21 Organic Compounds
6. Making and Using Graphs Make a graph of
Table 1. For each compound, plot the number
of carbon atoms on one axis and the number of
hydrogen atoms on the other axis. Use the graph
to predict the formula of hexane, which has six
carbon atoms. For more help, refer to the Science Skill Handbook.
7. Solving One-Step Equations Compare the
formulas of three saturated hydrocarbons: C2H6 ,
C3H8 , and C4H10. What mathematical relationship do you see between the number of carbon
atoms and the number of hydrogen atoms in
each? Compare the number of carbon and the
number of hydrogen atoms in the unsaturated
hydrocarbons C2H4 , C3H6 , and C4H8. For more
help, refer to the Math Skill Handbook.
SECTION
Other Organic
Compounds
Aromatic Compounds
Chewing flavored gum or dissolving a candy mint in your
mouth releases pleasant flavors and aromas. Many chemical compounds produce pleasant odors but others have less pleasant flavors and smells. For example, aspirin, which has an unpleasant,
sour taste, is shown in Figure 7A. The compound that produces
the fresh fragrance of wintergreen is shown in Figure 7B. Both of
these compounds are considered aromatic compounds. In addition to the fragrances mentioned here, aromatic compounds
contribute to the smell of cloves, cinnamon, anise, and vanilla.
You might assume that aromatic compounds are so named
because they are smelly—and most of them are. However, smell
is not what makes a compound aromatic in the chemical sense.
To a chemist, an aromatic compound is one that contains a
benzene structure having a ring with six carbons.
■
Define aromatic compounds.
Identify the nature of alcohols
and acids.
■ Identify organic compounds
you use in daily life.
■
Vocabulary
aromatic compound
substituted hydrocarbon
alcohol
Aromatic compounds are building
blocks of thousands of useful
compounds, such as flavorings
and medicines.
What structure is found in all aromatic
compounds?
Figure 7
You can see the six-carbon
benzene ring in these aromatic
compounds.
Aspirin is acetyl
salicylic acid.
Wintergreen is
methyl salicylate.
H
—
O
C—O—C—H
—
C — OH
—
—
O
H
—
O — C — CH3
OH
O
SECTION 2 Other Organic Compounds
645
Figure 8
Benzene, C6H6, can be
represented by a
spacefilling model,
a structural
formula, or
the benzene
symbol.
H
C—
C
—
H
H
—
C—
C—
C
—
H
C
H
H
Benzene C6H6
Benzene Look at a model of benzene, C6H6, and its structural
formula in Figure 8. As you can see, the benzene molecule has six
carbon atoms bonded into a ring. The electrons shown as alternating double and single bonds that form the ring are shared by
all six carbon atoms in the ring. This equal sharing of electrons
is represented by the special symbol shown in Figure 8C. The
sharing of these electrons causes the benzene molecule to be
very stable because all six carbon atoms are bound in a rigid, flat
structure. Many compounds contain this stable ring structure.
The stable ring acts as a framework upon which new molecules
can be built.
What is responsible for the stability of the
benzene ring?
Fused Rings Moth crystals have a distinct odor. One type of
Naphthalene
C10H8
Figure 9
Naphthalene used in moth
crystals is an example of a
fused-ring system.
moth crystal is made of naphthalene (NAF thuh leen). This is a
different type of aromatic compound that is made up of two
ring structures fused together, as shown in Figure 9. Many
known compounds contain three or more rings fused together.
Tetracycline (te truh SI kleen) antibiotics are based on a fused
ring system containing four fused rings.
Substituted Hydrocarbons
Usually a cheeseburger is a hamburger covered with melted
American cheese and served on a bun. However, you can make a
cheeseburger with Swiss cheese and serve it on toast. Such substitutions would affect the taste of this cheeseburger.
In a similar way chemists change hydrocarbons into other
compounds having different physical and chemical properties.
They may include a double or triple bond or add different atoms
or groups of atoms to compounds. These changed compounds are
called substituted hydrocarbons.
646
CHAPTER 21 Organic Compounds
A substituted hydrocarbon has one or more of its hydrogen
atoms replaced by atoms or groups of other elements. Depending on what properties are needed, chemists decide what to add.
Examples of substituted hydrocarbons are shown in Figure 10.
Carbon compounds also
are found in space. About
five percent of meteorites
contain water and carbon
compounds. Carbon compounds, such as formic acid
and a form of acetylene,
have been detected in
outer space using radio
telescopes. The areas
where they are found are
thought to be regions of
space where new stars
are forming.
Alcohols and Acids Rubbing alcohol gets its name from
the fact that it was used for rubbing on aching muscles. Rubbing
alcohol is a substituted hydrocarbon. Alcohols are an important
group of organic compounds. They serve often as solvents and
disinfectants, and more importantly can be used as pieces to
assemble larger molecules. An alcohol is formed when –OH
groups replace one or more hydrogen atoms in a hydrocarbon.
Figure 10A shows ethanol, an alcohol produced by the fermentation of sugar in grains and fruit.
Why are alcohols considered substituted
hydrocarbons?
Organic acids form when a carboxyl group, –COOH, is substituted for one of the hydrogen atoms attached to a carbon
atom. Look at Figure 10. The structures of ethane, ethanol, and
acetic acid are similar. Do you see that acetic acid, found in
vinegar, is a substituted hydrocarbon? You know some other
organic acids, too—citric acid found in citrus fruits, such as
oranges and lemons, and lactic acid found in sour milk.
H H
Ethanol
C2H5OH
Substituted hydrocarbons come in a variety of forms.
Most ethanol, C2H5OH, often called grain alcohol, is
obtained from corn.
Acetic acid is found in vinegar.
Tetrachloroethene is a compound used in dry cleaning.
H
O
—
H — C — C — OH
Figure 10
— —
H
— —
— —
H
H—C—C
OH
H
Acetic acid
CH3COOH
Cl
Cl
C— C
Cl
Cl
Tetrachloroethene
C2Cl4
SECTION 2 Other Organic Compounds
647
Substituting Other Elements Other atoms besides
Figure 11
Strangely, small concentrations
of foul-smelling compounds are
often found in pleasant-smelling
substances. For example, the
mercaptan in skunk spray is
among the 834 components of
coffee aroma.
hydrogen and oxygen can be added to hydrocarbons. One is
chlorine. When four chlorine atoms replace four hydrogen
atoms in ethylene, the result is tetrachloroethene (teh truh klor
uh eth EEN), a solvent used in dry cleaning. It is shown in
Figure 10C. Adding four fluorine atoms to ethylene makes a
compound that can be transformed into a black, shiny material
used for nonstick surfaces in cookware. Among other possible
substituted hydrocarbons are molecules containing nitrogen,
bromine, and sulfur.
When sulfur replaces oxygen in the –OH group of an alcohol, the resulting compound is called a thiol, or more commonly a mercaptan. Most mercaptans have unpleasant odors. This
can be useful to animals like the skunk shown in Figure 11.
Mercaptan odors are not only unpleasant, they are also
powerful. You can smell skunk spray even in concentrations as
low as 0.5 parts per million. Though you might not think so,
such a powerful stink can be an asset, and not just for skunks. In
fact, smelly mercaptans can save lives. As you know natural gas
has no odor of its own so it is impossible to smell a gas leak. For
this reason, gas companies add small amounts of a bad-smelling
mercaptan to the gas to make people aware of any leaks before
gas can accumulate to dangerous levels.
Section
Assessment
1. What do the structures of all aromatic
compounds have in common?
2. How is each of the following a substituted
hydrocarbon: tetrachloroethene, ethanol,
and acetic acid?
3. What elements other than oxygen could
be added to a hydrocarbon to produce a
substituted hydrocarbon?
4. Explain why chemists might want to prepare substituted hydrocarbons. Give two
examples of possible substitutions.
5. Think Critically Chloroethane, C2H5Cl,
can be used as a spray-on anesthetic for
localized injuries. How does chloroethane
fit the definition of a substituted hydrocarbon? Diagram its structure.
648
CHAPTER 21 Organic Compounds
6. Interpreting Scientific Illustrations Formic
acid, HCOOH, is the simplest organic acid. Draw
its structural formula by referring to the structure of acetic acid in Figure 10B. For more
help, refer to the Science Skill Handbook.
7. Communicating Examine the different ways
a benzene molecule can be represented, as
shown in Figure 8. Do you think the double
bonds in the structural formula shown in
Figure 8B must always be written in the positions shown? In your Science Journal, explain
your answer and discuss why benzene can be
represented by a six-sided figure containing
a circle. For more help, refer to the Science
Skill Handbook.
Alcohols and Organic Acids
H
ave you ever wondered how chemists
change one substance into another? You
have learned that changing the bonding among
atoms holds the key to that process.
What You’ll Investigate
How can an alcohol change into an acid?
Materials
large test tube and stopper
0.01M potassium permanganate solution (1 mL)
6M sodium hydroxide solution (1 mL)
ethanol (3 drops)
10-mL graduated cylinder
Safety Precautions
Always handle these chemicals with care;
immediately flush any spill with water.
Goals
■ Control the immediate environment of a
reaction to produce a specific compound.
■ Gather evidence to form conclusions about
the identity of a new compound formed from
a chemical reaction.
Procedure
1. Pour 1 mL of 0.01M potassium permanganate solution and 1 mL of 6M sodium
hydroxide solution into a test tube.
2. Add 3 drops of ethanol to the test tube.
3. Stopper the test tube. Gently shake it for
1 minute. Observe and record any changes in
the solution for 5 minutes.
Conclude and Apply
1. What is the structural formula for ethanol?
2. What part of a molecule identifies a compound as an alcohol?
3. What part of a molecule identifies a compound as an organic acid?
4. Explain how you know that a chemical
change took place in the test tube.
5. In the presence of potassium permanganate,
an alcohol may undergo a chemical change
into an acid. If ethanol is used, predict the
formula of the acid produced.
6. The acid from ethanol is found in a common
household product—vinegar. What is the
acid’s chemical name?
Design a table and record what changes take
place in the color of the solution. Compare
your observations with those of other
students in your class. For more help, refer
to the Science Skill Handbook.
ACTIVITY
649
SECTION
Petroleum—A Source
of Carbon Compounds
What is petroleum?
■
Explain how carbon compounds
are obtained from petroleum.
■ Compare and contrast differences
among the various petroleumbased fuels.
■ Determine how carbon compounds can form long chains.
■ Identify some of the ways petroleum enriches your world.
Vocabulary
polymer
monomer
polyethylene
Petroleum gives us fuels, plastics,
clothing, and many other products.
Do you carry a comb in your pocket or purse? What is it
made from? If you answer plastic, you are probably right, but do
you know where that plastic came from? Chances are it came
from petroleum—a dark, flammable liquid, often called crude
oil, that is found deep within Earth. Like coal and natural gas,
this dark, foul-smelling substance is formed from the remains of
fossilized material. For this reason these substances often are
called fossil fuels.
How can a thick, dark liquid like petroleum be transformed
into a hard, brightly colored, useful object like a comb? The
answer lies in the nature of petroleum. Petroleum is a mixture of
thousands of carbon compounds. To make items such as combs,
the first step is to extract the crude oil from its underground
source, as shown in Figure 12. Then, chemists and engineers
separate it into its individual compounds using a physical property that you have learned about. This property is the boiling
point. Even though petroleum contains a large number of compounds, each compound has its own boiling point.
Separating Petroleum Compounds The separation process
is known as fractional distillation.
It takes place in petroleum refineries. If you have ever driven past a
refinery, you may have seen these
big, metal towers called fractionating towers. They often rise as high
as 35 m and can be 18 m wide and
have pipes and metal scaffolding
attached to the outside.
Ocean surface
Oil platform
Ocean floor
Oil wells
Natural gas
Oil
Rock layers
650
CHAPTER 21 Organic Compounds
Figure 12
Drilling for petroleum beneath the
ocean floor requires huge platforms.
The Tower Inside the tower is a series of
metal plates arranged like the floors of a
building. These plates have small holes so
that vapors can pass through. On the outside you can see a maze of pipes at various
levels. The tower separates crude oil into
fractions containing compounds having a
range of boiling points. Within a fraction,
boiling points may range more than 100°C.
Hydrocarbon gases
used for fuels and
plastics
Below 20°C
40°C – 200°C
Gasoline
Kerosene
How It Happens The crude petroleum
175°C – 275°C
at the base of the tower is heated to more
than 350°C. At this temperature most
250°C – 400°C
hydrocarbons in the mixture become
vapor and start to rise. The higher boiling
fractions reach only the lower plates before
Above 300°C
they condense, forming shallow pools that
drain off through pipes on the sides of the
tower and are collected.
Above 350°C
Fractions with lower boiling points
may climb higher to the middle plates
Heated
before condensing. Finally, those with the
crude oil
lowest boiling points condense on the topmost plates or never condense at all and
are collected as gases at the top of the
tower. Figure 13 shows some typical fractions and how they are used.
Why don’t the condensed liquids fall back through the holes?
The reason is that pressure from the rising vapors prevents this.
In fact, the separation of the fractions is improved by the interaction of rising vapors with condensed liquid. The processes
involved vary. For example, some towers add steam at the bottom to aid vaporization. The design and process used depend on
the type of crude oil and on the fractions desired.
Jet fuel and diesel oil
Lubricating oil
Asphalt
Figure 13
Typical fractions are separated in
a fractionating tower by their
boiling points.
Uses for Petroleum Compounds
Some fractions are used directly for fuel—the lightest fractions from the top of the tower include butane and propane.
The fractions that condense on the upper plates and contain
from five to ten carbons are used for gasoline and solvents.
Below these are fractions with 12 to 18 carbons that are used for
kerosene and jet fuel. The bottom fractions go into lubricating
oil, and the residue is used for paving asphalt. Figure 14 shows
the variety of useful products that can be obtained from petroleum, in addition to its use as a fuel.
SECTION 3 Petroleum—A Source of Carbon Compounds
651
Figure 14
VISUALIZING PETROLEUM
PRODUCTS
P
etroleum, or crude oil, provides the raw material
for a huge number of products that have become
essential to modern life. After it has been refined,
petroleum can be used to make various types of fuel,
plastics, and synthetic fibers, as well as paint, dyes,
and medicines.
MEDICINES The active
ingredient in aspirin
used to be extracted
from the bark of
willow trees. Today
it is manufactured
from petroleum.
FABRICS Like the
fleece used to make
these gloves, many
modern fabrics
are made from
synthetic, rather
than natural,
fibers. Some of
the most popular synthetic fibers—polyester and
nylon are petroleum-based.
PRINTING INK
The ink used in
newspapers is made
from carbon black,
another product
from petroleum.
FUELS This commuter jet
is being refueled at an airport. Most of the world’s
petroleum is still used in
the form of fuel.
PLASTICS The durability
of hard plastic makes it
the ideal material for a
cell phone keypad.
652
Polymers
Did you ever loop together strips of paper to make paper
chains for decorations, or have you ever strung paper clips
together? A paper chain can represent the structure of a polymer
as shown in Figure 15. Some of the smaller molecules from
petroleum can act like links in a chain. When these links are
hooked together, they make new, extremely large molecules
known as polymers. The small molecule, which forms a link in
the polymer chain, is called a monomer. Mono means one.
How are polymers similar to paper chains or
linked paper clips?
Common Polymers One common polymer or plastic is
made from the monomer ethene or ethylene. Under standard
room-temperature conditions, this small hydrocarbon is a gas.
However, when ethylene combines with itself repeatedly, it
forms a polymer called polyethylene. Polyethylene (pah lee EH
thuh leen) is used widely in shopping bags and plastic bottles.
Another common polymer is polypropylene (pah lee PRO puh
leen) used to make glues and carpets. Often two or more different monomers, known as copolymers, combine to make one
polymer molecule.
Polymers can be made light and flexible or so strong that
they can be used to make plastic pipes, boats, and even some
auto bodies. In many cases, they have replaced natural building
materials, such as wood and metal. Because so many things used
today are made of synthetic polymers, some people call this “The
Age of Plastics.”
Visualizing Polymers
Procedure
1. Use paper clips to represent
monomers in a synthetic
polymer. Hook about 20
together to make a chain.
2. Cut 20 strips of colored
paper and mark each with
a different letter of the
alphabet from A to T.
3. Assemble these strips in
random order to make a
paper chain.
Analysis
1. Imagine both chains
extended to contain
10,000 or more units.
Compare them in terms of
ease of construction and
degree of complexity.
2. Compare the paper chains
made by your class. How
many different combinations of letters are there?
Figure 15
Imagine this paper chain extended by 10,000 units.Then
imagine each link as a monomer. Now you have an idea
of what a typical polymer used to make plastic looks like.
SECTION 3 Petroleum—A Source of Carbon Compounds
653
Figure 16
Processing can modify a polymer’s properties.
Polystyrene
used in CD cases is clear, hard, and brittle.
Polystyrene used
in cups is opaque, light-weight, and foamy.
Designing Polymers The properties of polymers depend
Research Visit the
Glencoe Science Web site at
science.glencoe.com to
learn more about polymers.
Communicate to your class
what you learn.
mostly on which monomers are used to make them. Also, like
hydrocarbons, polymers can have branches in their chains. The
amount of branching and the shape of the polymer greatly
affect its properties.
Polymer materials can be shaped in many ways. Some are
molded to make containers or other rigid materials. Sometimes
the same polymer can take two completely different forms. For
example, polystyrene (pah lee STI reen) that is made from
styrene, shown in Figure 16, forms brittle, transparent cases for
CDs and lightweight, opaque, foam cups and packing materials.
To make this transformation, a gas such as carbon dioxide is
blown into melted polystyrene as it is molded. Bubbles remain
within the polymer when it cools, making polystyrene foam an
efficient insulator.
Other polymers can be spun into threads, which are used
to make clothing or items such as suitcases and backpacks.
Fibers can be made strong and durable for products that receive
wear and tear. Others can resist strong impacts. For example,
bullet-proof vests are made of a tightly woven, synthetic polymer. Polymer fibers also can be made stretchy and resilient for
fabric products like exercise garments. Some polymers remain
rigid when heated, but others become soft and pliable when
heated and harden again when cooled.
Name some applications of polymer fibers.
654
CHAPTER 21 Organic Compounds
Other Petroleum Products
—
O
Other fractions obtained from fractional distillation of petroleum may be purified further by different techniques to isolate individual compounds. After
these are separated, they can be converted into substituted hydrocarbons, as you learned in the last section.
Chemists use these to make products ranging from
medicines such as aspirin to dyes, insecticides,
printers’ ink, and flavorings.
Many of the products that come from petroleum
are aromatic compounds. For example, the sweetener
saccharin is related to toluene, a substituted benzene
molecule. It has from 200 to 700 times the sweetening
power of sugar, but no calories. In fact, it passes
unchanged through the digestive tract. Although
other sweeteners are available today, saccharin still is used
widely in many diet foods and to sweeten mouthwash, as shown
in Figure 17.
Also, aromatic dyes have replaced natural dyes, such as indigo
and alizarin, almost completely. The first synthetic dye was a
bright purple called mauve that was discovered accidentally in
coal tar compounds. Today, most dyes come from petroleum.
Section
C
NH
SO2
Figure 17
Saccharin is used as a sweetener
because it doesn’t damage teeth
like sugar can.
Assessment
1. What is petroleum and where does it
come from?
2. Why are some fuels referred to as
fossil fuels?
3. Which fractions of petroleum are used
directly for fuel? How are they obtained
from petroleum?
4. What is the name for substances made
from thousands of small molecules that
are linked together? What are the small
molecules called?
5. Think Critically Petroleum fractions
obtained by fractional distillation contain
many individual compounds. How might
these mixtures be separated further? What
physical property could be used?
6. Predicting Based on the names of the
polymers and monomers in this section,
what do you think polymers made from the
monomers terpene and urethane would be
called? For more help, refer to the Science
Skill Handbook.
7. Communicating Research at least two
synthetic polymers other than those mentioned
in this section. Write in your Science Journal
which monomers they include, the approximate
length of their chains, and how they are used.
Describe their properties and, if possible, how
they are related to polymer structure. Report
your findings to your class. For more help, refer
to the Science Skill Handbook.
SECTION 3 Petroleum—A Source of Carbon Compounds
655
SECTION
Biological Compounds
Biological Polymers
■
Compare and contrast proteins,
nucleic acids, carbohydrates,
and lipids.
■ Identify the structure of polymers
found in basic food groups.
■ Identify the structure of large
biological polymers.
Vocabulary
protein
nucleic acid
deoxyribonucleic acid (DNA)
carbohydrate
lipid
Like the polymers that are used to make the plastics and
fibers, biological polymers are huge molecules. Also, they are
made of many smaller monomers that are linked together. The
monomers of biological polymers are usually larger and more
complex in structure. Still, you can picture a biological
monomer as one link in a very long chain.
Many of the important biological compounds in your body
are polymers. Among them are the proteins, which often contain hundreds of units.
Proteins
H
Glycine
—
O
—
—
OH
H
H—C—H
H
H
OH
Cysteine
H
Figure 18
In a protein polymer, peptide
bonds link together molecules
of amino acids.
656
CHAPTER 21 Organic Compounds
Peptide bonds
link molecules
of amino acids.
N
H
H
H—C—H
—
—
N—C—C
O ⴙ HOH
C—C
—
—
—
— —
O
—
S—H
H
H
Each amino acid
also contains a
carboxylic acid
(–COOH) group.
H—N—C—C
—
N—C—C
H
S—H
O
—
H
—
—
Each amino acid
contains an
amine (–NH2 )
group.
— —
All life processes depend on large
biological compounds.
Proteins are large organic polymers formed from organic
monomers called amino acids. Even though only 20 amino
acids are commonly found in nature, they can be arranged in
so many ways that millions of different proteins exist. Proteins
come in numerous forms and make up many of the tissues in
your body, such as muscles and tendons, as well as your hair
and fingernails. In fact, proteins account for 15 percent of your
total body weight.
H
OH
Water is formed
from the –OH of a
carboxylic group
and the –H of an
amine group.
Figure 19
Four peptide chains coil around each
other in the protein polymer hemoglobin. Each chain has an atom of
iron, which carries oxygen.
Iron atom
carrying oxygen
Protein Monomers Amino acids are the monomers that combine to form proteins. Two amino acids are shown in Figure 18A.
The –NH2 group is the amine group and the –COOH group is the
carboxylic acid group. Both groups appear in every amino acid.
Amine groups of one amino acid can combine with the
carboxylic acid group of another amino acid, linking them
together to form a compound called a peptide as shown in
Figure 18B. The bond joining them is known as a peptide bond.
When a peptide contains a large number of amino acids—about
50 or more—the molecule is called a protein.
Approximately how many amino acid units
does a protein contain?
Protein Structure Long protein molecules tend to twist and
coil in a manner unique to each protein. For example, hemoglobin, which carries oxygen in your blood, has four chains that
coil around each other as shown in Figure 19. Each chain contains an iron atom that carries the oxygen. If you look closely,
you can see all four iron atoms in hemoglobin.
When you eat foods that contain proteins, such as meat,
dairy products, and some vegetables, your body breaks down
the proteins into their amino acid monomers. Then your body
uses these amino acids to make new proteins that form muscles,
blood, and other body tissues.
SECTION 4 Biological Compounds
657
Nucleic Acids
Data Update Visit the
Glencoe Science Web site at
science.glencoe.com for
recent news of magazine
articles about DNA fingerprinting. Communicate to
your class what you learn.
The nucleic acids are another important group of organic
polymers that are essential for life. They control the activities
and reproduction of cells. One kind of nucleic acid, called
deoxyribonucleic (dee AHK sih ri boh noo klay ihk) acid or
DNA, is found in the nuclei of cells where it codes and stores
genetic information. This is known as the genetic code.
Nucleic Acid Monomers The monomers that make up
DNA are called nucleotides. Nucleotides are complex molecules
containing an organic base, a sugar, and a phosphoric acid unit.
In DNA two nucleotide chains twist around each other forming
what resembles a twisted ladder or what is called the double
helix. Human DNA contains only four different organic bases,
but they can form millions of combinations. The bases on one
side of the ladder pair with bases on the other side, as shown in
Figure 20. The genetic code gives instructions for making other
nucleotides and proteins needed by your body.
Problem-Solving Activity
Selecting a Balanced Diet
hat do you like to eat? You probably
choose your foods by how good they
taste. A better way might be to look at their
nutritional value. Your body needs nutrients
like proteins, carbohydrates, and fats to give
it energy and help it build cells. Almost
every food has some of these nutrients in it.
The trick is to pick your foods so you don’t
get too much of one thing and not enough
of another.
W
Identifying the Problem
The table on the right lists some
basic nutrients for a variety of foods. The
amount of the protein, carbohydrate, and
fat is recorded as the number of grams in
100 g of the food. By examining these data,
can you select the foods that best provide
each nutrient?
658
CHAPTER 21 Organic Compounds
Solving the Problem
1. Using the table, list the foods that supply
the most protein and carbohydrates.
What might be the problem with eating
too many potato chips?
2. In countries where meat and dairy products are hard to get, people eat a lot of
food made from soybeans. Can you
think of reasons why people might wish
to substitute meat and dairy products
with soybean based products?
Nutritional Values for Some Common Foods
Food (100 g) Protein (g) Carbohydrate (g) Fat (g)
Cheddar
cheese
25
01
33
Hamburger
17
23
17
Soybeans
13
11
07
Wheat
15
68
02
Potato chips
07
53
35
DNA Fingerprinting Human DNA contains more than
5 billion base pairs. The DNA of each person differs in some
way from that of everyone else, except for identical twins, who
share the same DNA sequence. The unique nature of DNA
offers crime investigators a way to identify criminals from hair
or fluids left at a crime scene. DNA from bloodstains or cells in
saliva found on a cigarette can be extracted in the laboratory.
Then, chemists can break up the DNA into its nucleotide components and use radioactive and X-ray methods to obtain a
picture of the nucleotide pattern. Comparing this pattern to
one made from the DNA of a suspect can link that suspect to
the crime scene.
Carbohydrates
If you hear the word carbohydrate, you
may think of bread, cookies, or pasta. Have
you heard of carbohydrate loading by athletes? Runners, for example, often prepare
for a long-distance race by eating, or loading up on, carbohydrates in foods such as
vegetables and pasta. Carbohydrates are
compounds containing carbon, hydrogen,
and oxygen, that have twice as many
hydrogen atoms as oxygen atoms. Carbohydrates include the sugars and starches.
Base pairs
Nucleotides
Figure 20
DNA models show how nucleotides are
arranged in DNA. Each nucleotide looks
like half of a ladder rung with an attached
M613-22C-MSS02
side piece. As you can see, each
pair of
DNA
double
helix structure
nucleotides forms a rung on the ladder,
while the side pieces give the ladder a little
twist that gave DNA the name double helix.
SECTION 4 Biological Compounds
659
H
O
H HOCH2
C
C
C
OH
— —
C
— —
HO
H
H
OH
C
C
H
HO
O
C
C
OH
H
H
C
H
— —
H
— —
H
O
C
OH
HO
HO
— —
C
C
— —
— —
CH2OH
C
H
OH
Glucose C6H12O6
CH2OH
Sucrose C12H22O11
Sugars Sugars are a major group of carbohydrates, as shown
in Figure 21. The sugar glucose is found in your blood and also
in many sweet foods such as grapes and honey. Common table
sugar, known as sucrose, is broken down by digestion into two
simpler sugars—fructose, often called fruit sugar, and glucose.
Unlike starches, sugars provide quick energy soon after eating.
Figure 21
Starches Starch, shown in Figure 22, is a carbohydrate that is
Sucrose and glucose are sugars
found in foods. Fruits contain
glucose and another simple
sugar called fructose. Why are
sugars carbohydrates?
also a polymer. It is made of units or monomers of the sugar
glucose. During digestion, the starch is broken down into
smaller molecules of glucose and other similar sugars, which
release energy in your body cells.
Athletes, especially long-distance runners, use starches to
provide high-energy, long-lasting fuel for the body. The energy
from starches can be stored in liver and muscle cells in the form
of a compound called glycogen. During a long race, this stored
energy is released, giving the athlete a fresh burst of power.
Figure 22
Starch is the major component
of pasta.
Lipids
Fats, oils, and related compounds make up a group of
organic compounds known as lipids. Lipids include animal fats
such as butter, and vegetable oils such as corn oil. Lipids contain
the same elements as carbohydrates but in different proportions. For example, lipids have fewer oxygen atoms and contain
carboxylic acid groups.
How are lipids like carbohydrates? How are
they different?
— —
— —
H
OH
C
C
OH
O
CHAPTER 21 Organic Compounds
C
H
OH
C
C
OH
O
— —
— —
H
C
H
C
H H
H
OH
C
H H
H
C
C
OH
H
C
O
O
C
H
C
— —
C
O
— —
H
H
C
C
H H
— —
C
O
CH2OH
— —
C
O
C
H H
H
OH
660
O
CH2OH
— —
C
— —
C
H H
CH2OH
— —
— —
CH2OH
H
OH
C
O
Fats and Oils These substances are similar in structure to
hydrocarbons. They can be classified as saturated or unsaturated,
according to the types of bonds in their carbon chains. Saturated
fats contain only single bonds between carbon atoms. Unsaturated fats having one double bond are called monounsaturated,
and those having two or more double bonds are called polyunsaturated. Animal lipids or fats tend to be saturated and are
solids at room temperature. Plant lipids called oils are unsaturated and are usually liquids, as shown in Figure 23. Sometimes
hydrogen is added to vegetable oils to form more saturated solid
compounds known as hydrogenated vegetable shortenings.
Have you heard that eating too much fat can be unhealthy?
Evidence shows that too much saturated fat and cholesterol in
the diet may contribute to some heart disease and that unsaturated fats may help to prevent heart disease. It appears that saturated fats are more likely to be converted to substances that can
block the arteries leading to the heart. A balanced diet includes
some fats, just as it includes proteins and carbohydrates.
Cholesterol Another lipid that is often in the news is cholesterol, which is found in meats, eggs, butter, cheese, and fish.
Even if you never eat foods containing cholesterol, your body
makes its own. Some cholesterol is needed by the body to build
cell membranes. It is also found in bile, a digestive fluid. Too
much cholesterol may cause serious damage to heart and blood
vessels, similar to the damage caused by saturated fats.
Section
Figure 23
At room temperature, fats
are normally solids, and oils are
usually liquids.
Check the label on any
available container of milk.
What percentage of fat is
in the milk? Infer any
advantages of drinking
low-fat milk.
Assessment
1. What is a polymer? Why are polymers
important organic compounds? Give some
specific examples.
2. Compare and contrast proteins and nucleic
acids in terms of their structures and their
functions in your body.
3. Where does your body get the amino acids
it needs to build proteins?
4. Explain the difference between saturated
and unsaturated fats and oils. Which type
is considered healthier in foods?
5. Think Critically Is ethanol a carbohydrate? Explain.
6. Comparing and Contrasting In terms of DNA
fingerprinting, compare and contrast identical
twins and two people who are not identical
twins. For more help, refer to the Science
Skill Handbook.
7. Solving One-Step Equations Changing just
one amino acid in a chain changes the function
of the entire protein. If the letters G, L, C, and I
represent four amino acids, how many different
peptides containing four amino acids can be
made? For more help, refer to the Math
Skill Handbook.
SECTION 4 Biological Compounds
661
Preparing an Ester
A
re esters aromatic compounds? Organic compounds known as acids and alcohols
react to form another type of organic compound called an ester. Esters frequently
produce a recognizable and often pleasant fragrance, even though they are not aromatic in the chemical sense—they might not contain a benzene ring. Esters are
responsible for many fruit flavors, such as apple, pineapple, pear, and banana.
What You’ll Investigate
How do an acid and an alcohol combine to produce a compound with different characteristics? Can the presence of the new compound formed be detected by its odor?
Goals
Materials
■ Prepare an ester from an alcohol and
medium-size test tube
test-tube holder
250-mL beaker
10-mL graduated cylinder
water
hot plate
ring stand
thermometer
salicylic acid (0.2 g)
methyl alcohol (2 mL)
concentrated sulfuric acid (2 or 3 drops
to be added by teacher)
an acid.
■ Detect the results of the reaction by
the odor of the product.
Safety Precautions
WARNING: Sulfuric acid is caustic.
Avoid all contact. Mix all the contents
together using a glass stirring rod. Do not
use the thermometer as a stirring rod.
662
CHAPTER 21 Organic Compounds
Procedure
WARNING: Any compound you can
3. Add 2 mL of methyl alcohol to the
smell has entered your body, and
unknown compounds can be toxic or
caustic. To detect an aroma safely, hold
the container about 10 cm in front of your
face and wave your hand over the opening to direct air currents to your nose.
See the illustration below for the proper
way to detect odors in the laboratory.
1. Add about 150 mL of water to the
beaker and heat it on the hot plate
to 70ºC.
2. Place approximately 0.2 g of
salicylic acid in a test tube. Does
this material have an odor?
test tube. Before adding it, check to
see if this compound has an odor.
If so, try to remember what it
smells like.
4. Ask your teacher to add carefully
three to five drops of concentrated
sulfuric acid.
5. Place the test tube in the hot water
and leave it untouched for about
12 to 15 minutes.
6. Remove the tube from the hot
water using a test-tube holder and
allow it to cool. Check to see if you
can detect a new aroma.
Conclude and Apply
1. What did you smell in step 6?
2. Look closely at the surface of the
3. Look at the equation for the reaction
below. One product is given. What
do you think is the second product
formed in this reaction?
liquid in the test tube. Do you see
any small droplets of an oily substance? What do you think it is?
H
H
—
—
C—O—C—H ⴙ ?
—
O
OH
—
—
C — OH ⴙ HO — C — H →
—
OH
—
H
—
Waft the vapor toward
your face gently.
O
H
Write a description of your experiment in
your Science Journal. Suggest how you might
modify the experiment to produce a different
ester. For more help, refer to the Science
Skill Handbook.
ACTIVITY
663
Accidents
in SCIENCE
SOMETIMES GREAT DISCOVERIES HAPPEN BY ACCIDENT!
A SP
ILL
for a
sp
664
ll
n 1953, American
chemist Patsy
Sherman invented a
way to protect fabrics
from accidental spills.
Strangely enough, this
discovery came about
because of an accidental
spill in her lab.
I
“How many great discoveries would never have
occurred were it not for
accidents?” asks Sherman.
i
“We were trying to develop a new kind of
rubber for jet aircraft fuel lines,” Sherman
once explained, “when one of the lab assistants accidentally dropped a glass bottle that
contained a batch of synthetic latex I had
made. Some of the latex mixture splashed on
the assistant’s canvas tennis shoe and the
result was remarkable.”
The latex mixture didn’t stain the shoe or
change it in any way. But it simply would not
come off.
Neither soap nor alcohol nor any other
cleaning material could remove the stubborn
mixture from the shoe. In fact, the mixture
actually made water bead and run off the
shoe in much the same way that water runs
off a duck’s back.
Perfecting the Product
Although the lab assistant was frustrated
by the mixture’s staying power, Sherman was
inspired. She realized that it could be used to
protect fabrics from oil, water, and dirt. She
spent three years working with another
chemist to perfect the product, which came
on the market in 1956. The substituted
hydrocarbon compound that Sherman developed makes fabrics more durable as well as
stain resistant. It bonds to the fibers in the
fabric and protects them like an invisible
shield. Today, the carpet in your home, the
fabric that covers the couch in your living
room, and some of the clothes that you wear
are likely treated with the fabric protector
invented by Sherman. Her product is especially useful on uniforms for people who
spend a lot of time outdoors in difficult, dirty,
or messy situations, such as firefighters,
police officers, and military personnel.
Encouraging Young Inventors
Sherman had a successful career as a
chemist and inventor before she retired in
1992. She often speaks to students about the
life of an inventor and encourages them to
pursue their dreams. Sherman stresses that a
creative mind is a scientist’s best tool.
“Anyone can become an inventor,” she insists,
“as long as they keep an open and inquiring
mind and never overlook the possible significance of an accident or apparent failure.”
Patsy Sherman and her team have made
mud on the rug easier to deal with.
CONNECTIONS Experiment Pour a small amount of water on
a piece of cloth that has been treated with fabric protector. Do the
same to a piece of untreated cloth. What happened to the water in both
cases? What happened to the pieces of cloth?
For more information, visit
science.glencoe.com
Chapter
21
Study Guide
Section 1 Simple Organic Compounds
1. Carbon is an element with a structure that
enables it to form a large number of compounds, known as organic compounds.
2. Saturated hydrocarbons contain only
single bonds between carbon atoms.
Unsaturated hydrocarbons contain double
or triple bonds.
3. Many camp
stoves burn
butane. How
many carbon
atoms are
in a butane
molecule?
4. Isomers of organic compounds have identical formulas but different molecular shapes.
Section 2 Other Organic Compounds
1. Aromatic compounds, many of which have
odors, contain the benzene ring structure.
2. Cookware often
has a nonstick
coating. This
coating is a
hydrocarbon
polymer in
which fluorine
replaces some
hydrogen
atoms. What are
such hydrocarbons called?
3. Benzene rings are stable because all six carbon atoms are bound tightly on one plane.
4. Aromatic compounds include those having
two or more rings fused together.
666
CHAPTER STUDY GUIDE
Section 3 Petroleum—A Source of
Carbon Compounds
1. Petroleum is a mixture of thousands of
carbon compounds.
2. A fractionating tower separates petroleum
into groups of compounds or fractions
based on their boiling points.
3. Small hydrocarbons obtained from petroleum can be combined to make long chains
called polymers, which are used for plastics.
4. Polymers can be
spun into fibers
designed to have
specific properties. What property is important
in spandex fibers?
Section 4 Biological Compounds
1. Proteins, nucleic acids, carbohydrates,
and lipids are major groups of biological
organic compounds.
2. Many important biological compounds are
polymers, huge organic molecules made of
smaller units, or monomers.
3. The pain-producing components of wasp venom
are peptides. What are the
monomers of peptides?
FOLDABLES
After You Read
Use each of the vocabulary
words on your Foldable
in a complete sentence
that explains something about the organic
compounds discussed in this chapter.
Reading &Study
& Study
Skills
21
Chapter
Complete the following
concept map about types of
organic compounds.
Study Guide
Carbon
forms
Organic compounds
include
include
Other organic
compounds
include
Hydrocarbons
include
include
include
Aromatic
Compounds
Alcohols
and acids
Unsaturated
hydrocarbons
Saturated
Hydrocarbons
have
have
have
have
Benzene rings
OH & COOH
Groups
Multiple
bonds
Single
bonds
Vocabulary Words
a. alcohol
b. aromatic
compound
c. carbohydrate
d. deoxyribonucleic
acid (DNA)
e. hydrocarbon
f. isomer
g. lipid
h. monomer
i. nucleic acid
j. organic compound
k. polyethylene
l. polymer
m. protein
n. saturated
hydrocarbon
o. substituted
hydrocarbon
p. unsaturated
hydrocarbon
Study Tip
Think of other ways that you might design
an experiment to prove scientific principles.
Consider controls and variables.
Using Vocabulary
Replace the underlined words with the correct
vocabulary words.
1. Isomers are compounds that contain the
element carbon.
2. An alcohol forms a link in a polymer chain.
3. Protein is the nucleic acid that contains
your genetic information.
4. An unsaturated hydrocarbon contains the
benzene-ring structure.
5. Organic compounds such as sugars and
starches are called proteins.
6. Organic compounds such as fats and oils
are called isomers.
7. Lipids are compounds with identical
chemical formulas but different structures.
CHAPTER STUDY GUIDE
667
Chapter
21
Assessment
Choose the word or phrase that best answers
the question.
1. How would you describe a benzene ring?
A) rare
C) unstable
B) stable
D) saturated
2. How would you classify hydrocarbons, such
as alcohols and organic acids?
A) aromatic
C) substituted
B) saturated
D) unsaturated
3. What are the small units that make up
polymers called?
A) monomers
C) plastics
B) isomers
D) carbohydrates
4. What type of compound is hemoglobin
found in red blood cells?
A) carbohydrate
C) nucleic acid
B) lipid
D) protein
5. RNA tells your body how to make proteins.
What does DNA code and store?
A) lipids
C) protein
B) nucleic acids
D) genetic
information
6. What type of compounds form the DNA
molecule?
A) amino acids
C) polymers
B) nucleotides
D) carbohydrates
7. Glucose and fructose both have the formula
C6H12O6. What are such compounds called?
A) amino acids
C) isomers
B) alcohols
D) polymers
8. If a carbohydrate has 16 oxygen atoms, how
many hydrogen atoms does it have?
A) 4
C) 16
B) 8
D) 32
9. What type of compound is cholesterol?
A) sugar
C) protein
B) starch
D) lipid
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CHAPTER ASSESSMENT
10. Which petroleum fractions are collected at
the top of a fractionating tower?
A) highest boiling
C) lowest boiling
B) liquid
D) polymer
11. Too much saturated or unsaturated fat in
your diet is unhealthful. How do they differ
in composition?
12. Propyl alcohol and isopropyl alcohol have
the formula C3H80. How might their structures differ?
13. Draw a diagram to explain single, double,
and triple bonds in hydrocarbons. Draw a
chain of carbon atoms that shows each type
of bond.
14. Explain the term fraction when used to
describe the products produced during
petroleum refining. Describe the process by
which these products are obtained.
15. Making and Using Graphs Using the following table, plot the number of carbon
atoms on one axis and the boiling point on
the other axis on a graph. Use the graph to
predict the boiling points of butane, octane,
and dodecane (C12H26).
Hydrocarbons
Name
Formula
Boiling Point (ºC)
Methane
CH4
–162
Ethane
C2H6
–89
Propane
C3H8
–42
16. Recognizing Cause and Effect Anthracene
is a compound containing three fused rings
similar to the benzene ring. How would you
explain the stability of this compound?
Chapter
17. Interpreting Scientific Illustrations
Which of the following terms apply to
the illustration below: alcohol, aromatic,
carbohydrate, hydrocarbon, lipid, organic
compound, polymer, saturated, and substituted hydrocarbon.
C— C—C—H
H
Assessment
Test Practice
The common alcohol methanol is
represented by the following chemical
symbol:
H
— —
H
—
H
21
H
18. Concept Mapping Make a network tree
to describe types of fats. Include the
terms saturated fats, unsaturated fats,
single bonds, and double bonds.
19. Hypothesizing A weight-reduction diet
allows no food other than lettuce and fresh
fruit for three days a week. What is missing
from the diet on these days?
20. Scientific Drawing Research three
hydrocarbons containing five carbon
atoms. Draw diagrams of their structures,
name them, and tell their uses.
21. Surveying and Graphing Record the fiber
content of your clothing, noting whether it
is synthetic or natural. Make a circle graph
comparing the percentages of natural and
synthetic fibers.
TECHNOLOGY
Go to the Glencoe Science Web site at
science.glencoe.com or use the
Glencoe Science CD-ROM for additional
chapter assessment.
CH3OH
Methanol
Study the chemical formula above and
answer the following questions.
1. According to this chemical formula, all
of the following elements are found in
methanol EXCEPT _________.
A) carbon
B) nitrogen
C) hydrogen
D) oxygen
2. How many carbon atoms are there in
the compound methanol?
F) one
G) two
H) three
J) four
3. How many electrons are shared in each
of the bonds linking the carbon atom
in methanol to the three hydrogen
atoms?
A) one
B) two
C) three
D) four
CHAPTER ASSESSMENT
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