Download Chapter 4 Summary

Chapter 4 Summary
Concept 4.1

Organic chemistry is the study of carbon compounds

Organic compounds were once thought to arise only within living organisms, but
this idea (vitalism) was disproved when chemists were able to synthesize organic
compounds in the laboratory .
Concept 4.2

Carbon atoms can form diverse molecules by bonding to four other atoms

A covalent–bonding capacity of four contributes to carbon′s ability to form
diverse molecules.

Carbon can bond to a variety of atoms, including O, H, and N.
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Carbon atoms can also bond to other carbons, forming the carbon skeletons of
organic compounds.

The carbon skeletons of organic molecules vary in length and shape and have
bonding sites for atoms of other elements.

Hydrocarbons consist only of carbon and hydrogen.

Isomers are molecules with the same molecular formula but different structures
and properties.

Three types of isomers are structural isomers, geometric isomers, and
enantiomers.
Concept 4.3

Functional groups are the parts of molecules involved in chemical reactions

Functional groups are chemically reactive groups of atoms within an organic
molecule that give the molecule distinctive chemical properties.

The hydroxyl group (–OH) is polar, thus helping compounds dissolve in water.

The carbonyl group ( CO) can be either at the end of a carbon skeleton
(aldehyde) or within the skeleton (ketone).

The carboxyl group (–COOH) is found in carboxylic acids. The hydrogen of this
group can dissociate, making such molecules weak acids.

The amino group (–NH2) can accept a proton (H+), thereby acting as a base.

The sulfhydryl group (–SH) helps stabilize the structure of some proteins.

The phosphate group (–OPO32−) has an important role in the transfer of energy.

When a phosphate group splits off from ATP, energy is released that can be used
by the cell.

Living matter is made mostly of carbon, oxygen, hydrogen, and nitrogen, with
some sulfur and phosphorus.
Biological diversity has its molecular basis in carbon′s ability to form a huge
number of molecules with particular shapes and chemical properties.

Self–Quiz
1. Organic chemistry is currently defined as
a. the study of compounds that can be made only by living cells.
b. the study of carbon compounds.
c. the study of vital forces.
d. the study of natural (as opposed to synthetic) compounds.
e. the study of hydrocarbons.
2. Choose the pair of terms that correctly completes this sentence: Hydroxyl is to
________ as ____________ is to aldehyde.
a. carbonyl; ketone
b. oxygen; carbon
c. alcohol; carbonyl
d. amine; carboxyl
e. alcohol; ketone
3. Which of the following hydrocarbons has a double bond in its carbon skeleton?
a. C3H8
b. C2H6
c. CH4
d. C2H4
e. C2H2
4. The gasoline consumed by an automobile is a fossil fuel consisting mostly of
a. aldehydes.
b. amino acids.
c. alcohols.
d. hydrocarbons.
e. thiols.
5. Choose the term that correctly describes the relationship between these two sugar
molecules: SEE BOOK
a. structural isomers
b. geometric isomers
c. enantiomers
d. isotopes
6. Identify the asymmetric carbon in this molecule:
SEE BOOK
7. Which functional group is not present in this molecule?
SEE BOOK
a. carboxyl
b. sulfhydryl
c. hydroxyl
d. amino
8. Which action could produce a carbonyl group?
a. the replacement of the hydroxyl of a carboxyl group with hydrogen
b. the addition of a thiol to a hydroxyl
c. the addition of a hydroxyl to a phosphate
d. the replacement of the nitrogen of an amine with oxygen
e. the addition of a sulfhydryl to a carboxyl
9. Which functional group is most likely to be responsible for an organic molecule
behaving as a base?
a. hydroxyl
b. carbonyl
c. carboxyl
d. amino
e. phosphate
10. Given what you know about the electronegativity of oxygen, predict which of the
following molecules would be the strongest acid. Explain your answer.
a. SEE BOOK
b.
Evolution Connection
Some scientists believe that life elsewhere in the universe might be based on the element
silicon, rather than on carbon, as on Earth. What properties does silicon share with carbon
that would make silicon–based life more likely than, say, neon–based life or aluminum–
based life? (See Figure 2.8.)
Scientific Inquiry
In 1918, an epidemic of sleeping sickness caused an unusual rigid paralysis in some
survivors, similiar to symptoms of advanced Parkinson′s disease. Years later, L–dopa, a
chemical used to treat Parkinson′s disease (see Figure 4.8), was given to some of these
patients, as dramatized in the movie Awakenings. L–Dopa was remarkably effective at
eliminating the paralysis, at least temporarily. However, its enantiomer, D–dopa, was
subsequently shown to have no effect at all, as is the case for Parkinson′s disease.
Suggest a hypothesis to explain why, for both diseases, one enantiomer is effective and
the other is not.
Investigation What Factors Determine the Effectiveness of Drugs?
Science, Technology, and Society
Thalidomide achieved notoriety 50 years ago because of a wave of birth defects among
children born to women who took thalidomide during pregnancy as a treatment for
morning sickness. However, in 1998 the U.S. Food and Drug Administration (FDA)
approved this drug for the treatment of certain conditions associated with Hansen′s
disease (leprosy). In clinical trials, thalidomide also shows promise for use in treating
patients suffering from AIDS, tuberculosis, and some types of cancer. Do you think
approval of this drug is appropriate? If so, under what conditions? What criteria do you
think the FDA should use in weighing a drug′s benefits against its dangers?