Properties of Alkanes
At room temperature, the first four members of the alkane family are gases. The straight chain alkanes from pentane and up are liquids, and octadecane (18 carbons) and up in the alkane family are solids. As the number of carbons increases, the boiling point increases.
Branched alkanes have lesser boiling points than their unbranched or less branched isomeric counterparts. The reason for this is that the unbranched molecules have more intermolecular interactions than the branched ones.