Illustrated Glossary of Organic Chemistry

sp orbital: One of a set of hybrid orbitals produced when one s orbital and one p orbital are combined mathematically to form two new equivalent, perpendicular orbitals. These sp orbitals look similar to p orbitals, except that sp orbitals are closer to the nucleus.

	+		merge to form
s orbital	+	px orbital		two sp orbitals

The C-H bonds of acetylene are formed by overlapping a carbon sp orbital with a hydrogen 1s orbital. The resulting C-H bonds point away from each other, and have H-C-C bond angles of 180^o. In a similar manner, overlap of one sp orbital from each carbon forms the sigma bond portion of the alkyne's triple bond.