Life on Earth is based on a
vast array of organic or carbon-based compounds. All species of
plants and animals use them for structure and biological
Carbon is unique among the
known elements. As a nonmetal, it forms covalent bonds. A carbon
atom can form four bonds, so it can combine with several other atoms
in many different ways, thereby yielding a huge variety of diverse
Most chemicals known today are
organic, and many of them are found in nature. But chemists have
also synthesized millions of organic compounds not found in nature.
Chemists classify organic
molecules according to the functional groups they contain. A
functional group is a specific combination of bonded atoms that
reacts in a characteristic and predictable way.
We'll use functional groups as
a way of exploring the structure and function of organic compounds.
We'll start by learning the names and formulas of some biologically
important functional groups, then consider the structure and
function of food energy molecules and nitrogen-containing molecules.