I myself while searching and talking to my dad found the answer.Sounds weird, sorry for posting.
THE NAMES OF ORGANIC COMPOUNDS
Cracking the code
A modern organic name is simply a code. Each part of the name gives you some useful information about the compound.
For example, to understand the name 2-methylpropan-1-ol you need to take the name to pieces.
The prop in the middle tells you how many carbon atoms there are in the longest chain (in this case, 3). The an which follows the "prop" tells you that there aren't any carbon-carbon double bonds.
The other two parts of the name tell you about interesting things which are happening on the first and second carbon atom in the chain. Any name you are likely to come across can be broken up in this same way.
Counting the carbon atoms
You will need to remember the codes for the number of carbon atoms in a chain up to 6 carbons. There is no easy way around this - you have got to learn them. If you don't do this properly, you won't be able to name anything!
code no of carbons
meth 1
eth 2
prop 3
but 4
pent 5
hex 6
Types of carbon-carbon bonds
Whether or not the compound contains a carbon-carbon double bond is shown by the two letters immediately after the code for the chain length.
code means
an only carbon-carbon single bonds
en contains a carbon-carbon double bond
For example, butane means four carbons in a chain with no double bond.
Propene means three carbons in a chain with a double bond between two of the carbons.
Alkyl groups
Compounds like methane, $\ce{CH4}$, and ethane, $\ce{CH3CH3}$, are members of a family of compounds called alkanes. If you remove a hydrogen atom from one of these you get an alkyl group.
For example:
A methyl group is $\ce{CH3}$.
An ethyl group is $\ce{CH3CH2}$.
These groups must, of course, always be attached to something else.
Types of compounds
The alkanes
Example 1: Write the structural formula for 2-methylpentane.
Start decoding the name from the bit that counts the number of carbon atoms in the longest chain - pent counts 5 carbons.
Are there any carbon-carbon double bonds? No - an tells you there aren't any.
Now draw this carbon skeleton:
Put a methyl group on the number 2 carbon atom:
Does it matter which end you start counting from? No - if you counted from the other end, you would draw the next structure. That's exactly the same as the first one, except that it has been flipped over.
Finally, all you have to do is to put in the correct number of hydrogen atoms on each carbon so that each carbon is forming four bonds.
If you had to name this yourself:
Count the longest chain of carbons that you can find. Don't assume that you have necessarily drawn that chain horizontally. 5 carbons means pent.
Are there any carbon-carbon double bonds? No - therefore pentane.
There's a methyl group on the number 2 carbon - therefore 2-methylpentane. Why the number 2 as opposed to the number 4 carbon? In other words, why do we choose to number from this particular end? The convention is that you number from the end which produces the lowest numbers in the name - hence 2- rather than 4-.
If you want more detail goto: http://www.chemguide.co.uk/basicorg/conventions/names.html
