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1. HYBRIDISATION 

Learning outcomes

• To understand the concept of hybridisation.
• To understand sp hybridisation in more detailed .
• To identify more examples of sp hybridisation 

NOTE

Hybridization in Chemistry is defined as the concept of mixing two atomic orbitals to give rise to a new type of hybridized orbitals. This intermixing usually results in the formation of hybrid orbitals having entirely different energies, shapes, etc. The atomic orbitals of the same energy level mainly take part in hybridization. However, both fully filled and half-filled orbitals can also take part in this process, provided they have equal energy.

What is Hybridization?

Redistribution of the energy of orbitals of individual atoms to give orbitals of equivalent energy happens when two atomic orbitals combine to form a hybrid orbital in a molecule. This process is called *hybridization*.

During the process of hybridization, the atomic orbitals of comparable energies are mixed together and mostly involves the merging of two 's' orbitals or two 'p' orbitals or mixing of an 's' orbital with a 'p' orbital as well as 's' orbital with a 'd' orbital. The new orbitals thus formed are known as *hybrid orbitals*.

More significantly, hybrid orbitals are quite useful in explaining atomic bonding properties and molecular geometry.

Key Features of Hybridization

1. Atomic orbitals with equal energies undergo hybridization.

2. The number of hybrid orbitals formed is equal to the number of atomic orbitals mixing.

3. It is not necessary that all the half-filled orbitals must participate in hybridization. Even completely filled orbitals with slightly different energies can also participate.

4. Hybridization happens only during the bond formation and not in an isolated gaseous atom.

5. The shape of the molecule can be predicted if the hybridization of the molecule is known.

6. The bigger lobe of the hybrid orbital always has a positive sign, while the smaller lobe on the opposite side has a negative sign.

Types of Hybridization

Based on the types of orbitals involved in mixing, the hybridization can be classified as sp3, sp2,sp, sp3d, sp3d2. 

sp Hybridization

sp hybridization is observed when one s and one p orbital in the same main shell of an atom mix to form two new equivalent orbitals. The new orbitals formed are called sp hybridized orbitals. It forms linear molecules with an angle of 180 degrees.

This type of hybridization involves the mixing of one 's' orbital and one 'p' orbital of equal energy to give a new hybrid orbital known as an sp hybridized orbital.sp hybridization is also called diagonal hybridization. Each sp hybridized orbital has an equal amount of s and p character - 50% s and 50% p.

Examples of sp Hybridization:

1. All compounds of beryllium like BeF2, BeH2, BeCl2

2. All compounds of carbon-containing triple bond like C2H2.

Video

Assessment questions 

• What is hybridisation?
• Number of hybrid orbitals formed by the intermixing of one s orbital and one p orbital?
• Find the correct one from bracket — Shape of BeCl2

          ( Linear, Bent, Square planar)