In methanal formaldehyde , the carbon-oxygen double bond is formed by the overlap of hybrid orbitals from both the carbon and oxygen atoms. For the carbon atom, it is sp2 hybridized. In sp2 hybridization, one s orbital and two p orbitals combine to form three sp2 hybrid orbitals. In methanal, two of these sp2 hybrid orbitals form sigma bonds with two hydrogen atoms, and the third sp2 hybrid orbital forms a sigma bond with the oxygen atom.For the oxygen atom, it is also sp2 hybridized. In this case, one s orbital and two p orbitals combine to form three sp2 hybrid orbitals. One of these sp2 hybrid orbitals forms a sigma bond with the carbon atom, while the other two sp2 hybrid orbitals each contain a lone pair of electrons.The carbon-oxygen double bond in methanal consists of one sigma bond formed by the overlap of sp2 hybrid orbitals from both carbon and oxygen and one pi bond formed by the side-by-side overlap of the remaining unhybridized p orbitals from both carbon and oxygen .