The hydrocarbons attached
to functional groups are called radicals (from "radix", meaning
is the methyl radical, CHCH
is the ethyl radical, and so on.
This distinction between radicals and functional groups is an old
one in organic chemistry, but a useful one. A radical often is represented
simply by R,
as in ROH,
a general expression for an alcohol.
In this chapter we shall look at several important functional groups,
seeing first what chemical properties these groups give to a molecule,
and then how these properties are modified by the hydrocarbon radical
to which they are attached.