Alkanes are named according to their longest chain. Numbering of the longest chain begins on the side of the molecule that will give the lowest number for the attached alkyl groups.
If there is more than one group attached to the carbon chain, you write the carbon number on which each group is attached, before the alkyl group, separated by a hyphen (-). When naming the compound, the alkyl groups are organized in alphabetical order of the alkyl groups. However, the prefixes (di-, tri- …) are not considered in the alphabetical order; so ethyl would still come before dimethyl, because the “di-“ is overlooked for the purposes of placement.
If there are many identical groups attached to the chain, you indicate the number of groups with the appropriate Greek prefixes. The numbers of the carbon atoms to which the group is attached are separated by a comma.
It is important to be able to draw the structure of a compound from its name.
The first step is to draw the exact number of carbon atoms in the longest chain.
Then, number the carbon atoms from left to right.
Attach the appropriate groups.
Last, place the required number of hydrogen atoms on each carbon atom.
A structure with the carbon chain in the form of a ring is called a cyclic chain. You indicate a ring form with the prefix "cyclo" in front of the appropriate alkane.
Now you can name any alkane! Just follow these steps.
You name the longest chain as the appropriate alkane.
Then, each group attached to this chain is named as the appropriate alkyl group.
Finally, choose the appropriate numbering system for the chain. The number of the carbon atom which has an attached group is placed before the name of the appropriate alkyl group.
If you are feeling a little overwhelmed, persevere. This process will get easier with practice.