sp Hybridisation
The mixing of one s and one p orbital to give two linear hybrid orbitals at 180° to each other.
Formula / equation
2 hybrids, 180°
Unit
degrees
In depth
The two unhybridised p orbitals remain perpendicular and form two pi bonds, so sp carbon is always found in triple bonds or in cumulated double bonds. The high 50% s character pulls electrons close to the nucleus, making sp-hybridised C–H bonds unusually acidic and sp carbon notably electronegative.
Examples in the real world
Ethyne HC≡CH and carbon dioxide O=C=O, both perfectly linear; BeCl₂ in the vapour phase.