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OVERVIEW

The impact of ancient Aristotelian ideas on the development of understandings of motion, elements, and matter was
discussed in earlier chapters. Historians also trace the “vitalist theory” back to Aristotle. According to Aristotle’s
idea, all living organisms are composed of the four elements (earth, air, fire, and water) and have in addition an
actuating force, the life or soul that makes the organism different from nonliving things made of the same four
elements. Plants, as well as animals, were considered to have this actuating, or vital, force in the Aristotelian
scheme of things.
There were strong proponents of the vitalist theory as recently as the early 1800s. Their basic argument was
that organic matter, the materials and chemical compounds recognized as being associated with life, could not be
produced in the laboratory. Organic matter could only be produced in a living organism, they argued, because the
organism had a vital force that is not present in laboratory chemicals. Then, in 1828, a German chemist named
Friedrich Wöhler decomposed a chemical that was not organic to produce urea (N 2 H 4 CO), a known organic compound
that occurs in urine. Wöhler’s production of an organic compound was soon followed by the production of other
organic substances by other chemists. The vitalist theory gradually disappeared with each new reaction, and a new
field of study, organic chemistry, emerged.
This chapter is an introductory survey of the field of organic chemistry, which is concerned with compounds and
reactions of compounds that contain carbon. You will find this an interesting, informative introduction, particularly
if you have ever wondered about synthetic materials, natural foods and food products, or any of the thousands
of carbon-based chemicals you use every day. The survey begins with the simplest of organic compounds, those
consisting of only carbon and hydrogen atoms, compounds known as hydrocarbons. Hydrocarbons are the compounds
of crude oil, which is the source of hundreds of petroleum products (Figure 12.1).
Most common organic compounds can be considered derivatives of the hydrocarbons, such as alcohols, ethers,
fatty acids, and esters. Some of these are the organic compounds that give flavors to foods, and others are used to
make hundreds of commercial products, from face cream to oleo. The main groups, or classes, of derivatives will be
briefly introduced, along with some interesting examples of each group. Some of the important organic compounds
of life, including proteins, carbohydrates, and fats, are discussed next. The chapter concludes with an introduction to
synthetic polymers, what they are, and how they are related to the fossil fuel supply.

four and can combine with one, two, three, or four other car-
12.1 ORGANIC COMPOUNDS
bon atoms, in addition to a wide range of other kinds of atoms
Today, organic chemistry is defined as the study of com- (Figure 12.2). The number of possible molecular combina-
pounds in which carbon is the principal element, whether tions is almost limitless, which explains why there are so many
the compound was formed by living things or not. The study organic compounds. Fortunately, there are patterns of groups
of compounds that do not contain carbon as a central element of carbon atoms and groups of other atoms that lead to similar
is called inorganic chemistry. An organic compound is thus a chemical characteristics, making the study of organic chemistry
compound that contains carbon as the principal element, and less difficult. The key to success in studying organic chemistry is
an inorganic compound is any other compound. to recognize patterns and to understand the code and meaning
Organic compounds, by definition, must contain carbon, of organic chemical names.
whereas all the inorganic compounds can contain all the other
elements. Yet the majority of known compounds are organic.
Several million organic compounds are known, and thousands 12.2 HYDROCARBONS
of new ones are discovered every year. You use organic com-
pounds every day, including gasoline, plastics, grain alcohol, A hydrocarbon is an organic compound consisting of only two
foods, flavorings, and many others. elements. As the name implies, these elements are hydrogen
It is the unique properties of carbon that allow it to form and carbon. The simplest hydrocarbon has one carbon atom
so many different compounds. A carbon atom has a valence of and four hydrogen atoms (Figure 12.3), but since carbon atoms

300 CHAPTER 12 Organic Chemistry 12-2