Chemists observed that there were two types of substances. Those
from non-living matter and those from living matter. They were classified
into two categories which include inorganic substances and organic
substances. Many similar properties were observed by the Chemists. Most
inorganic substances were observed to change very little, if any, when
heated. Also, organic substances were thought to be produced only by
living organisms.
Later in time organic substances were studied in greater detail.
Chemists learned that nearly all organic compounds are made of chains and
rings of carbon atoms. Chemists then learned to synthesize some simple
organic compounds directly from inorganic substances! This amazing
discovery marked the beginning of modern organic chemist. Today we define
organic chemistry as the chemistry of carbon compounds. (pg.579, Smoot,
Price, and Smith, Merill Chemistry)
The largest group of organic compounds are the hydrocarbons. These
compounds are composed only of carbon and hydrogen. Almost all other
organic compounds can be considered as derivatives of the hydrocarbons. If
the carbon atoms are linked in chains, the compounds are called aliphatic
compounds. If the atoms are linked in rings, the compounds are called
cyclic compounds. (pg.581, ...ibid...)

(Biology Pamphlet)

In terms of naming organic compounds the number of carbon-carbon
chains are named using the prefixes below:

meth- 1 carbon
eth- 2
prop- 3
but- 4
pent- 5
hex- 6
hept- 7
oct- 8
non- 9
dec- 10

The simplest group of hydrocarbons is the alkanes. The carbon atom
in these hydrocarbons is always saturated with hydrogen atoms. The first
three members of the alkane family are methane - CH , ethane C H , and
propane - C H . After butane the members of the alkane series are named
using the Greek or Latin prefix for the numbering of carbon atoms.
(pg.580...ibid...) Alkanes are named according to the longest chain and
not according to the total number of carbon atoms in the molecule. The
word ending characteristic of this family is -ane. ***The most important
characteristic to remember is alkanes always mean single bonds, no multiple
bonds.
Alkanes are able to have the same formula but different molecular
structure, these types of alkanes are called isomers. They differ in the
number of neutrons and therefore have different mass numbers. Most organic
compounds have isomers. There is no known way of predicting exactly how
many isomers most compounds can form.
Unsaturated aliphatic hydrocarbons are the building blocks of the
organic chemical industry. The term "unsaturated" indicates that the
carbon atoms are not saturated with the maximum number of hydrogen atoms.
Saturated hydrocarbons bond with four other atoms. Unsaturated
hydrocarbons contain a multiple bond. There are 2 types of unsaturated
hydrocarbons which we will talk about. They are the alkenes and the
alkynes. (pg.73. Martin Sherwood, Chemistry Today.) These hydrocarbons may
combine with other elements of compounds by adding on at the multiple bond.
The alkenes contain double bonds and the alkynes contain triple bonds
between the carbon atoms. The naming begins with the side of the compound
starting with the multiple bond.

Aromatic Hydrocarbons

The simplest type of aromatic hydrocarbon is the benzene ring. The
structure of benzene is unusual. Instead of having alternate long single
and shorter double carbon-carbon bonds in the six-membered ring, all the
bonds are of equal length. Each carbon atom of the benzene ring is bonded
to a single hydrogen ...