Carbon oxides and carbonates are exceptions; they contain carbon but are considered inorganic because they do not contain hydrogen. The atoms of an organic molecule are typically organized around chains of carbon atoms. Inorganic compounds make up 1%–1.5% of a living cell's mass.
They are made up of only one type of element, which is carbon, and therefore would fail to be categorized as an organic compound since they are not, in the first place,a compound, but a pure element.
