13.3 Formula of Organic Compounds
An organic compound can be designated by molecular or structural formula. It gives a concise and instantly recognizable description of the compound.
Molecular formula : It is the formula which
expresses the exact number of atoms of each element present in the
molecule and does not distinguish between isomers.
Structural formula : It describes the actual
attachment of all atoms with one another in the molecule and distinguishes
The following table (21) illustrates how these formulae are used to represent the compound.
Note that entries 2 and 3 have similar molecular formulae but different structural formula. Such compounds are called isomers. Structure affects both the chemical reactivity and physical properties of compounds as illustrated in following table 22.