In 3C and 2H diamond, as well as in the extended lattice polytypes, the valence 4 electrons (2s 2 , 2p 2 ) arrange in tetrahedra with sp 3 -like hybridization; note that this term, as well as other carbon hybridizations (sp 2 and sp 1 ), are common in organic chemistry, and less so in the solid state chemistry; nevertheless, they are useful for establishing the chemical description of the bonding and the resulting physical and chemical properties.