The process of mixing of atomic orbitals of nearly same energy to produce a set of entirely new orbitals of equivalent energy (hybrid orbitals) is known as hybridization. Atomic orbitals of almost the same energy belonging to the same atom or ion can take part in hybridization.. The number of hybrid orbitals formed is always equal to the number of atomic orbitals taking part in hybridization. The hybrid orbitals repel each other and tend to be farthest apart. Hybrid orbitals forms only sigma(σ bonds) σ and pi bonds( π bonds )are formed by unhybridised orbitals.
Sigma bond: This type of covalent bond is formed by the axial or end to end overlapping of half filled atomic orbitals of the atoms participating in bonding. The electron cloud formed as a result of axial overlap is cylindrically symmetrical about inter nuclear axis.
Pi bond: This type of bond is formed by lateral or side wise overlap of the half filled atomic orbitals of the atoms participating in bonding. The pi bond consists of two charged clods above and below the plane of the atoms involved in bond formation.
Sigma bond vs Pi bond
Sigma bond (σ bonds)
1. The covalent bond formed by the overlap of atomic orbitals along the internuclear axis is called sigma bond.
2. The overlapping orbitals are oriented along the internuclear axis.
3. The bond is rotationally symmetrical around the internuclear axis
4. A as well as p orbitals can form this type of bonds.
5. It is stronger than a pi bond
Pi bond (π bonds)
1. The covalent bond formed by the lateral overlap of two p orbitals which are mutually parallel but oriented perpendicular to the internuclear axis is called a pi bond.
2. The overlapping orbitals are oriented perpendicular to the inter nuclear axis.
3. The bond is not rotationally symmetrical around the internuclear axis.
4. Only p orbitals can form this bond.
5. It is weaker than a sigma bond.