Alkanes whose carbons are connected in a row are called straight chain alkanes (unbranched) whereas compound with branched carbon chains are called branched alkanes. Cycloalkanes are alkanes that contain a ring of three or more carbons and are characterized by the molecular formula. The alkanes show general lack of chemical reactivity. Although they are extremely flammable. This lack of reactivity is reflected in another name frequently applied to this class of compounds. They are called paraffins, a word derived from the Latin words partum affins, little affinity. Alkanes whose carbons are connected in a row are called straight chain alkanes (unbranched) whereas compound with branched carbon chains are called branched alkanes. Cycloalkanes are alkanes that contain a ring of three or more carbons and are characterized by the molecular formula.