# -ene Nomenclature (semi-structural formulas)

Hi,

I was just confused as to the semi-structural formula nomenclature of -ene and -yne structures. The thing that I don't understand is the = sign in the formula.

For example:
CH3CH2CH=CH2

What does that equals sign mean? Does it represent where the double bond is located?

If so, why does ethene have the structural formula CH2CH2 instead of CH2=CH2

Thanks
-Rudders

alxm