A hydrocarbon of pentane has three isomeric forms:
CH₃-CH₂-CH₂-CH₂-CH₃ n-pentane (normal pentane) (C₅H₁₂)
CH₃-CH-CH₂-CH₃ iso-pentane (C₅H₁₂)
I
CH₃
CH₃
I
CH₃-C-CH₃ neo-pentane (C₅H₁₂)
I
CH₃
Isomers have the same qualitative and quantitative composition, but different structure.