sp2 hybridized carbons that are part of a C-C double bond are called alkenyl carbons. They possess a trigonal planar geometry. The term vinylic may also be used, although that tends to be reserved for the vinyl group, -CH2=CH. Note that the terms primary, secondary, tertiary, and quaternary only apply to sp3 hybridized carbons, not alkenyl or alkynyl carbons.