What is the composition of sp2 hybrid orbitals?

• A. One s and two p orbitals forming three sp2 orbitals arranged 90 degrees apart
• B. One s and two p orbitals forming three sp2 orbitals arranged 120 degrees apart
• C. One d and two p orbitals
• D. Four sp2 orbitals

Answer: (B)

Sp2 hybridization uses three equivalent orbitals to form bonds in a plane. This is achieved by mixing one s orbital with two p orbitals to give three sp2 hybrid orbitals. These three hybrids are identical in energy and lie in the same plane, separated by 120 degrees, giving a trigonal planar arrangement. The remaining unhybridized p orbital sits perpendicular to that plane and can participate in π bonding, as seen in carbon–carbon double bonds. So the composition is one s orbital plus two p orbitals forming three sp2 orbitals arranged 120 degrees apart.