In organic chemistry, a primary carbon is a carbon atom of an alkane or alkyl group that is bound to only one other carbon atom. It is thus sp<sup>3</sup>-hybridized and at the end of a carbon chain. In case of an alkane, three hydrogen atoms are bound to a primary carbon (see propane in the figure on the right). A hydrogen atom could also be replaced by a hydroxy group (), which would make the molecule a primary alcohol.