261.

What is meant by hybridization of atomic orbitals? Describe the shapes of sp, sp², sp³ hybrid orbitals.

The phenomenon of mixing of orbitals of the same atom with a slight difference in energies so to redistribute their energies and give new orbitals of equivalent energy and shape. It is called as hybridization.
These hybrid orbitals have minimum repulsion between their electron pairs and thus, are more stable. Hybridization helps indicate the geometry of the molecule.

Sp³ hybridisation; This type of hybridization involves the mixing of one orbital of s- sub level or three orbitals of the p-sublevel of the valence shell to form four sp³ hybrid orbitals of equivalent energies and shape. Each sp³ hybrid orbital has 25% s character and 75% p-character. These hybridised orbitals tend to lie as apart in space as possible so that repulsive interaction between them are minimum. The four sp3 hybrid orbitals are directed towards the four corners of a tetrahedron. The angle between the sp3 hybrid orbitals is 109.5.

Sp² hybridisation: This type of hybridization involves the mixing of one orbital of s- sublevel and two orbitals of p-sublevel of the valence shell to form three sp2 hybrid orbitals. These sp2 hybrid orbitals lie in a plane and are directed towards the corners of the equilateral triangle.
Each sp2 hybrid orbitals has one-third s- character and two -third p- character. sp2 hybridization is also called trigonal hybridisation.

sp-hybridisation: This type of hybridization involves the mixing of one orbital of the s-sublevel and one p-sublevel of the valence shell of the atom to form two sp- hybridised orbitals of equivalent shapes and energies. These sp hybridised orbitals are oriented in space at an angle of 180.