alphabetical order, then number in the direction that gives the rest of the alkyl
groups the lowest numbers possible.
Because all the members of the alkane series have single covalent bonds,
this series and all such structures are said to be saturated.
If the hydrocarbon molecule contains double or triple covalent bonds, it is
referred to as unsaturated.
PROPERTIES AND USES OF ALKANES
Properties for some straight-chain alkanes are indicated in Table 14. The trends in
these properties can be explained by examining the structures of alkanes. The
carbon-hydrogen bonds are nonpolar. The only forces of attraction between
nonpolar molecules are weak intermolecular, or London dispersion, forces. These
forces increase as the mass of a molecule increases.
The table also shows the physical states of alkanes. Smaller alkanes exist as
gases at room temperature, while larger ones exist as liquids. Gasoline and
kerosene consist mostly of liquid alkanes. Seventeen carbons are needed in the
chain for the solid form to occur. Paraffin wax contains solid alkanes.
The differences in the boiling points of mixtures of the liquid alkanes found
in petroleum make it possible to separate the various components by fractional
distillation. This is the major industrial process used in refining petroleum into
gasoline, kerosene, lubricating oils, and several other minor components.
Alkene Series (Unsaturated)
The alkene series has a double covalent bond between two adjacent carbon
atoms. The general formula of this series is CnH 2 n. In naming these compounds,
the suffix of the alkane is replaced by -ene. Two examples:
TIP
Alkenes have the form CnH 2 n.Naming a more complex example is: