Now, alkanes are a member of a family of hydrocarbons, and that simply means alkanes are composed entirely of carbons and H atoms. Now, all linear alkanes have the following molecular formula c subscript NH, subscript two N plus two, where N designates the number of carbons. For example, if N is ten, if we have an alkane composed of ten carbon atoms, that means we're going to have 22 H atoms. Two times ten plus two is 22. The simplest alkane is methane. Methane is composed of one carbon and four hydrogens.