of one s and one p orbital resulting in the formation of two equivalent sp hybrid orbitals. The suitable orbitals for sp hybridisation are s and p z , if the hybrid orbitals are to lie along the z-axis. Each sp hybrid orbitals has % s -character and % p -character. Such a molecule in which the central atom is sp -hybridised and linked directly to two other central atoms possesses linear geometry.
This type of hybridisation is also known as diagonal hybridisation. The two sp hybrids point in the opposite direction along the z-axis with projecting positive lobes and very small negative lobes, which provides more effective overlapping resulting in the formation of stronger bonds. Example of molecule having sp hybridisation BeCl : The ground state electronic configuration of Be is s s . In the exited state one of the s -electrons is promoted to vacant p orbital to account for its bivalency.
One s and one p -orbital gets hybridised to form two sp hybridised orbitals. These two sp hybrid orbitals are oriented in opposite direction forming an angle of °. Each of the sp hybridised orbital overlaps with the p -orbital of chlorine axially and form two Be- Cl sigma bonds. This is shown in Fig.
. . (II) sp hybridisation : In this hybridisation there is involvement of one s and two p -orbitals in order to form three equivalent sp hybridised orbitals. For example, in BCl molecule, the ground state electronic configuration of central boron atom is s s p .
In the excited state, one of the s electrons is promoted to vacant p orbital as Fig. . (a) Formation of sp hybrids from s and p orbitals; (b) Formation of the linear BeCl molecule Be Fig. .
Formation of sp hybrids and the BCl molecule a result boron has three unpaired electrons. These three orbitals (one s and two p ) hybridise to form three sp hybrid