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Chapter 4: Carbon
1. Identify the four most common elements in living things. Give the most common
valence for each element and explain the value of the valence in terms of the
element’s electron configuration.
2. Identify and define the three major types of isomers.
3. In Chapter 2 you learned what an isotope is. Since students often confuse this word with
isomer, please define each term here and give an example.
Definition
Example
isotope
isomer
4. You will need to master the chart on the last page and the information in it. Using the functional
groups, see if you can answer the following prompts:
a. –NH2
b. Can form cross-links that stabilize protein structure
c. Key component of ATP
d. Can affect gene expression
e. CH3
f. Is always polar
g. Determines the two groups of sugars
h. Has acidic properties
i. –COOH
j. Acts as a base
k. Circle and identify three functional groups in the molecule shown above.
Word Roots
hydro- = water (hydrocarbon: an organic molecule consisting only of carbon and hydrogen)
iso- = equal (isomer: one of several organic compounds with the same molecular formula but
different structures and, therefore, different properties)
enanti- = opposite (enantiomer: molecules that are mirror images of each other)
carb- = coal (carboxyl group: a functional group present in organic acids, consisting of a carbon
atom double-bonded to an oxygen atom and a hydroxyl group)
sulf- = sulfur (sulfhydryl group: a functional group that consists of a sulfur atom bonded to an
atom of hydrogen)
Multiple Choice
5. Which is an organic molecule?
a. Ne
b. O2
c. CH4
d. NaCl
e. H2O
6. Carbon atoms are the most versatile building blocks of the molecules used by living
organisms because _____.
a. carbon is the central atom of carbon dioxide, a necessary molecule for photosynthesis
b. carbon is the central atom in urea, a molecule used by many living organisms to
transport wastes from the body
c. each carbon atom acts as an intersection point from which a molecule can branch off in
up to four directions
d. carbon can combine with hydrogen to form hydrocarbons
e. all of the above
7. Which of the following functional groups is present in all amino acids?
a. –SH
b. –COH
c. –OH
d. -NH2
e. -OPO3-2
8. Which one of the following molecules has a carboxyl functional group?
a. R-NH2
b. R-COH
c. R-COOH
d. R-OPO3-2
e. R-SH
9. Which one of the following molecules
is a weak base?
a. R-NH2
b. R-SH
c. R-OH
d. R-COOH
e. none of the above
10. Which of the following molecules is a weak acid?
a. R-NH2
b. R-SH
c. R-OH
d. R-COOH
e. none of the above