sp Hybridization

Again, an electron from the 2s atomic orbital is promoted to the 2p_z atomic orbital to produce four unpaired electrons.

C*: 1s², 2s¹, 2p_x¹, 2p_y¹, 2p_z¹

Those written in bold are involved in the hybridization process. In this case, only one 2s-orbital and one 2p-orbital combine, this is known as sp hybridization. The mixing of these two atomic orbitals results in the formation of two energetically equivalent hybrid orbitals and two unchanged p-orbitals. sp Hybrid orbital systems adopt linear geometry. The remaining 2p_y and 2p_z atomic orbitals remain unhybridized and lie at right angles to the plane of the hybrid orbitals.