CHAPTER 14
LESSON 1
Carbon Chemistry
Elemental Carbon and
Simple Organic Compounds
Key Concepts
What do you think? Read the two statements below and decide
whether you agree or disagree with them. Place an A in the Before column
if you agree with the statement or a D if you disagree. After you’ve read
this lesson, reread the statements to see if you have changed your mind.
Before
Statement
• How is carbon unique
compared to other
elements?
• How does carbon bond
with other carbon atoms?
After
1. Charcoal and diamonds are made of carbon
atoms.
2. Carbon atoms often bond with hydrogen
atoms in chemical compounds.
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Elements in Living Things
All living organisms, such as humans, starfish, sunflowers,
and mosquitoes, have several things in common. They are
made of cells that contain carbon, hydrogen, oxygen, nitrogen,
and other elements. About 18 percent of the mass of all
living organisms is made of compounds that contain the
element carbon.
Except for water and some salts, most things that you put
in or on your body consist of compounds that contain
carbon. These carbon compounds could be food, clothing,
cosmetics, or medicine.
Build Vocabulary Skim the
headings in this lesson and
circle any words that you do
not know. After you read the
lesson, go back and define
these words. Refer to these
definitions as you study the
lesson.
Reading Check
1. Identify Which four
elements are in most living
organisms?
Organic Compounds
In the past, scientists thought that all carbon compounds
came from organisms that were alive or were once alive.
They called carbon compounds organic compounds because
of this connection with organisms. Scientists now know that
carbon is also in many nonliving things. Today, scientists
define an organic compound as a chemical compound that
contains carbon atoms usually bonded to at least one hydrogen atom.
Compounds such as carbon dioxide (CO2) and carbon
monoxide (CO) are not organic because they do not have
a carbon-hydrogen bond.
Reading Essentials
Carbon Chemistry
247
Understanding Carbon
A carbon atom is a unique element. It can easily combine
with other atoms and form millions of compounds. Carbon
has the atomic number 6. This means that a neutral carbon
atom has six protons and six electrons. Four of these
electrons are valence electrons which are in the outermost
energy level.
REVIEW VOCABULARY
covalent bond a chemical
bond formed by the sharing of
one or more pairs of electrons
between atoms
Atoms are chemically stable when they have eight valence
electrons. Carbon atoms become more chemically stable
through covalent bonding, as shown below. In a covalent
bond, carbon atoms have eight valence electrons, like a
stable, unreactive noble gas. Carbon often bonds with four
hydrogen atoms. For each carbon-hydrogen covalent bond,
the hydrogen atom donates one electron and the carbon
atom donates one electron, creating a shared pair.
Visual Check
1 electron
2 electrons
2. Identify For each
carbon-hydrogen bond, how
many electrons come from a
hydrogen atom?
4 electrons
+
C
4H
H
HCH
H
Key Concept Check
3. Describe How is
carbon unique compared
to other elements?
The periodic table shows you that silicon and germanium
are in the same group as carbon. This means that their
atoms also have four valence electrons. Atoms of silicon and
germanium become stable by forming four covalent bonds.
However, it takes more energy for them to do this. The
more energy it takes, the less likely it is that bonding will
occur.
The Forms of Pure Carbon
When carbon atoms bond together, they form one of
several different arrangements. Forms of pure carbon are
discussed below and shown in the figure on the next page.
Graphite In graphite (GRA fite), carbon atoms form thin
sheets. The thin sheets are held together by weak forces.
These thin sheets can slide over one another or bend.
Graphite is used as a lubricant (LEW brih kunt), a frictionreducing film. It is also used in making golf clubs, tennis
rackets, pencil lead, and other items.
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Carbon Chemistry
Reading Essentials
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The Carbon Group
Diamonds Not only are diamonds used in jewelry, but also
on the tips of drill bits and the cutting edges of some saw
blades. Each carbon atom in a diamond is tightly bonded to
four other carbon atoms. The bonds between carbon atoms
in diamonds are extremely strong. These strong bonds make
diamonds one of the hardest materials known.
Fullerene Carbon atoms in fullerene (FOOL uh reen) are
cagelike structures, as shown below. Fullerene was discovered
late in the twentieth century, and uses for it are still being
explored. However, future fullerene uses might include the
development of faster, smaller electronic components.
Amorphous The atoms in amorphous (uh MOR fus) carbon
lack an orderly arrangement. Amorphous carbon is found in
soot, coal, and charcoal. Each form of carbon is shown below.
Forms of Carbon
Graphite
Diamond
Visual Check
4. Compare the structures
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
of graphite and diamonds.
Why is graphite used in
pencil lead but diamonds are
not?
Fullerene
Amorphous Carbon
Buckyball
Nanotube
Hydrocarbons
Many organic compounds contain only carbon and
hydrogen atoms. A compound that contains only carbon and
hydrogen atoms is called a hydrocarbon. There are many
different hydrocarbons. The simplest is methane (CH4).
Reading Essentials
Carbon Chemistry
249
Hydrocarbon Chains
5. Name What kind of
chains do carbon atoms form?
Butane
Isobutane
Molecular formula:
C4H10
Molecular
formula: C4H10
Molecular
formula: C4H8
—
H
H
H
—
—
—
—
—
—
—
—
—
—
—
—
H H
Structural formula
—
H H H
Structural formula
—
H H H H
Structural formula
—
H—C—C— H
———
H—C—C—C—H
H
—
H—C—C—C—C—H
H
—
H—C—C— H
H
—
H — C —H
H
H
H
Interpreting Tables
6. Compare butane and
Cyclobutane
—
Reading Check
When carbon atoms form hydrocarbons, the carbon
atoms can link together in different ways. They can form
straight chains, branched chains, or rings. Look closely at
the molecular formula for each of the compounds in the
table below. Notice that butane and isobutane have the
same molecular formula. They have the same ratio of carbon
atoms to hydrogen atoms. Compounds that have the same
molecular formula but different structural arrangements are called
isomers (I suh murz). Each isomer is a different molecule
with its own unique name and properties.
isobutane.
When a carbon atom bonds to another carbon atom,
the two atoms can share two, four, or six electrons. These
different options are shown in the figure on the next page.
The result of each of these cases is that the carbon atoms in
each molecule have eight valence electrons and are stable.
Key Concept Check
7. Describe What kind of
bonds do carbon atoms form
with other carbon atoms?
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Carbon Chemistry
When two carbon atoms share two electrons, they form
a single bond. A hydrocarbon that has only single bonds is
called an alkane. When two carbon atoms share four electrons,
they form a double bond. A hydrocarbon that has at least one
double bond is called an alkene. When two carbon atoms
share six electrons, they form a triple bond. A hydrocarbon
that has at least one triple bond is called an alkyne.
Reading Essentials
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Carbon-to-Carbon Bonding
Alkane – single bond
Alkene – double bond
• two electrons shared between
two carbon atoms
CH3 — CH3
• four electrons shared between
two carbon atoms
single
line
denotes
single
bond
double
line
denotes
double
bond
HH
HC C H
HH
CH2 — CH2
HC C H
H H
Make a three-quarter book
to organize your notes about
hydrocarbons and how they
bond.
1. Wha
t
hydrocis a
arbon?
s
2
n
.
W
o
b
h
at is
ar
3. Wha an alkane?
Hydroc
t is
4. Wha an alkene?
t is an a
lkyne?
Alkyne – triple bond
• six electrons shared between
two carbon atoms
triple
line
denotes
triple
bond
CH —
— CH
HC
Visual Check
8. Identify What type of
bond is found in alkene?
C H
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Saturated Hydrocarbons
Hydrocarbons are often classified by the type of bonds the
carbon atoms share. A hydrocarbon that contains only single bonds
is called a saturated hydrocarbon. It is called saturated because
no more hydrogen atoms can be added to the molecule. An
alkane, shown above, is a saturated hydrocarbon. Three of the
valance electrons in each carbon atom bond with hydrogen
atoms. The carbon atoms are saturated with hydrogen atoms.
Unsaturated Hydrocarbons
A hydrocarbon that contains one or more double or triple bonds
is called an unsaturated hydrocarbon. An alkene has a double
bond. An alkyne has a triple bond. If the double and triple
bonds are broken, additional hydrogen atoms could bond
to the carbon atoms. This means that double and triple
bonds are not saturated with hydrogen atoms. These
molecules, shown above, are unsaturated.
Naming Hydrocarbons
Most geometric shapes have names that refer to the
number of sides they have. For example, a triangle has three
sides, and the prefix tri– means “three.” Hydrocarbons have
names that indicate how many carbon atoms are in each
molecule.
Reading Essentials
Reading Check
9. Compare What is the
difference between saturated
and unsaturated
hydrocarbons?
Carbon Chemistry
251
Carbon Chains
When naming a hydrocarbon, the first thing you need
to do is find the longest carbon chain and count the number
of carbon atoms in it. Look at the figure below. The carbon
chain is formed by the darker atoms. Find the carbon chain
and count the carbon atoms. There are four carbon atoms
in this molecule. The number of carbon atoms gives you the
root word of the name. Now look at the table below. This
table shows the root word for any hydrocarbon that has one
through ten carbon atoms. What is the root name for the
molecule below? The molecule has four carbon atoms, so
the root name is but– (BYEWT).
Visual Check
C4 H10
10. Analyze How many
carbon atoms are in this
hydrocarbon (C4 H10)?
(Circle the correct answer.)
a. 2
b. 4
c. 10
Root Words
Interpreting Tables
11. Identify How many
Name
Carbon
Atoms
Name
1
meth–
6
hex–
2
eth–
7
hept–
3
prop–
8
oct–
4
but–
9
non–
5
pent–
10
dec–
Determine the Suffix
Now that you know how to find the root word of a
hydrocarbon, you must also find the suffix, or end, of the
name. Recall that carbon atoms bond to other carbon atoms
with single, double, or triple bonds. The table below shows
which suffix to use when you know the type of bond.
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Carbon Chemistry
Bond Type
Suffix
All single bonds — C — C —
–ane
At least one double bond — C — C —
–ene
At least one triple bond — C —
—C—
–yne
Reading Essentials
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
carbon atoms are in a
molecule with the root word
hept–?
Carbon
Atoms
Look again at the molecule on the previous page. The
molecule has only single bonds. This means that it should
have the suffix –ane. Thus, when you put the root and the
suffix together, you get the name for the molecule. It is
butane. The table below lists the steps for naming
hydrocarbons.
Reading Check
12. Name the hydrocarbon
Determine the Prefix
Sometimes hydrocarbons have a prefix and sometimes
they do not. Recall that hydrocarbons form chains, branched
chains, and rings. If a hydrocarbon contains a ring structure,
the prefix cyclo– is added before the root name.
with six carbon atoms that
contains only single bonds.
Steps for Naming Hydrocarbons
—
CH2
—
H—C—
—C—C—C—H
H
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
H
H
—
—
CH
— 2—
CH2
CH2
H
—
—
1. Examine the
compound.
Example B
—
Example A
CH2
CH2 —
2. Count the num- There are 4 carbon atoms
ber of carbon
in the longest chain.
atoms in the longest continuous
chain.
There are 6 carbon
atoms in the longest
chain.
3. Determine the
The root name is but–.
root name of the
hydrocarbon (see
the Root Words
chart on page 6).
The root name is
hex–.
4. Determine the
There is a triple bond, so
type of bonds in add the suffix –yne.
the hydrocarbon,
then use the
table on page 6
to find the suffix.
There are only single
bonds, so add the
suffix –ane.
5. Put the root and
suffix together
to name the
hydrocarbon.
Combining the root and
suffix gives the name
butyne.
Combining the root
and suffix gives the
name hexane.
6. If the hydrocarbon is a ring, add
cyclo– to the
beginning of the
name.
No prefix is needed
because the structure is
not a ring. The name of the
hydrocarbon is butyne.
The structure is a
ring, so the prefix
cyclo– is added to the
name. The name of
the hydrocarbon is
cyclohexane.
Reading Essentials
Interpreting Tables
13. Explain When
should cyclo– be added to
the beginning of the
hydrocarbon name?
Carbon Chemistry
253
Mini Glossary
hydrocarbon: a compound that contains only carbon and
saturated hydrocarbon: a hydrocarbon that contains only
hydrogen atoms
single bonds
isomers (I suh murz): compounds that have the same
unsaturated hydrocarbon: a hydrocarbon that contains
molecular formula but different structural arrangements
one or more double or triple bonds
organic compound: a chemical compound that contains
carbon atoms usually bonded to at least one hydrogen atom
1. Review the terms and their definitions in the Mini Glossary. Write a brief explanation of
how scientists’ definition of the term organic compound has changed over time.
2. Complete and fill in the steps below to name the following unknown hydrocarbon.
H
C
C
H
H
C
C
H
H
H
a. Count the number of carbon atoms in the longest chain.
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
b. Determine the root name.
c. Determine the suffix.
d. Name the hydrocarbon.
3. In what ways do you use carbon in everyday life?
What do you think
Reread the statements at the beginning of the
lesson. Fill in the After column with an A if you
agree with the statement or a D if you disagree.
Did you change your mind?
254
Carbon Chemistry
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END OF
LESSON
Reading Essentials