Chain Isomerism
Structural isomerism arising from different arrangements of the carbon skeleton.
Unit
Dimensionless
In depth
Straight and branched chains of the same formula are chain isomers. Branching reduces the molecular surface area available for London dispersion forces, so branched isomers consistently boil lower than their straight-chain counterparts.
Examples in the real world
Pentane boils at 36 °C, 2-methylbutane at 28 °C, and 2,2-dimethylpropane at just 10 °C.