Question

What is the correct name of the longest chain of $5$ carbon atoms?

Answer 1

IUPAC Nomenclature

• In order to clearly identify the compound, a systematic method of naming has been developed and is known as IUPAC (Internation Union of Pure and Applied Chemistry) system of nomenclature.

Rules of IUPAC nomenclature

• In order to define the length of the carbon chain, names are given as
• For one carbon atom - Methane $\left({\mathrm{CH}}_4\right)$
• Two carbon atoms chain- Ethane $({\mathrm{CH}}_3-{\mathrm{CH}}_3)$
• Three carbon atoms chain- Propane $({\mathrm{CH}}_3-{\mathrm{CH}}_2-{\mathrm{CH}}_3)$
• Four carbon atoms chain- butane $({\mathrm{CH}}_3-{\mathrm{CH}}_2-{\mathrm{CH}}_2-{\mathrm{CH}}_3)$
• Five carbon atoms chain- Pentane $({\mathrm{CH}}_3-{\mathrm{CH}}_2-{\mathrm{CH}}_2-{\mathrm{CH}}_2-{\mathrm{CH}}_3)$

Thus, the correct name of the longest chain of $5$ carbon atoms is Pentane.