5 Steps to a 5 AP Chemistry 2019

276 ❯ STEP 4. Review the Knowledge You Need to Score High

Macromolecules are found in nature. Cellulose, wool, starch, and DNA are but a few

of the macromolecules that occur naturally. Carbon’s ability to form these large, complex

molecules is necessary to provide the diversity of compounds needed to make up a tree or

a human being. But many of the useful macromolecules that we use every day are created

in the lab and industrial complex by chemists. Nylon, rayon, polyethylene, and polyvinyl

chloride are all synthetic macromolecules. They differ by which repeating units (mono-

mers) are joined together in the polymerization process. Our society has grown to depend

on these plastics, these synthetic fabrics. The complexity of carbon compounds is reflected

in the complexity of our modern society.

Experiments

Any experiment would probably apply the concepts of organic chemistry in a synthesis

situation.

Common Mistakes to Avoid

1. When writing organic formulas, make sure that every carbon has four bonds.


2. When naming alkanes, make sure to number the carbon chain so the sum of all location
   numbers is as small as possible.

Macromolecules

As we mentioned in the introduction to this chapter, carbon has the ability to bond to

itself in long and complex chains. These large molecules, called macromolecules, may

have molecular masses in the millions. They are large, complex molecules, but most are

composed of repeating units called monomers. Figure 18.4 shows two macromolecules,

cellulose and nylon, and indicates their repeating units.

H

H

HO OH

CH 2 OH

H H

O

O

H

H

H

HO OH

CH 2 OH

H

H

O

O

H

H

H

HO OH

CH 2 OH

H

H

O

O

H

H

H

HO OH

CH 2 OH

H

H

O

O

Repeating unit H

Cellulose

HO C

O

CNHNHH

n

(CH 2 ) 4

O

(CH 2 ) 6

Nylon

Figure 18.4 Two macromolecules.

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