Naming system
An organic molecule can have a trivial name or a systematic name. A trivial name, or common name, is a non systematic name which can be different from one region to another. On the other hand, systematic name is based on the rule established by IUPAC (International Union of Pure and Applied Chemistry). Systematic name is used globally.
CH3COOH is commonly known as acetic acid. This name is derived from the word acetum, the latin word for vinegar. Its systematic name is ethanoic acid, which shows that it is a carboxylic acid (-oic acid) and it contains 2 carbon atoms (eth-).
In AS and A Level chemistry examination, you are required to be able to give a systematic name to a given compound.
Naming hydrocarbons
In general, the systematic name of an organic molecule consists of a stem + a suffix. A prefix can be added to show the presence and location of side chains or functional groups.
The stem is