Carbon atoms have the unique ability to bond to other carbon atoms and form
chains which may also have branches.
This is the reason that the molecular size is so great in organic chemistry. Molecular
weights in the thousands are not uncommon. Three types of bonds are formed
between carbon atoms.
a. Single Bonds. A single bond is a covalent bond formed by two carbon
atoms sharing two electrons. Compounds that contain only single bonds between
carbon atoms are called alkanes.
b. Double Bonds. A double bond consists of two covalent bonds formed by two
carbon atoms sharing four electrons as shown below.
Compounds that contain at least one carbon-carbon double bond are referred to as
c. Triple Bonds. A triple bond consists of three covalent bonds formed by two
carbon atoms sharing six electrons as shown below.
Compounds that contain at least one triple bond between carbon atoms are called
The simplest organic compounds are the hydrocarbons, which are composed
solely of carbon and hydrogen. Since there are only two elements involved, one might
expect there would be only a few different compounds. However, carbon does bond to
itself and form long chains. So there are many, many different hydrocarbons. They can
be classed in two general groups, aliphatic and aromatic. These compounds are the
starting point for all organic compounds.