Difference Between Sigma and Pi Bond

Chemical bonds are forces which keep atoms joined together. Chemical bonds are classified into covalent bond, coordinate bond, ionic bond and hydrogen bond. Covalent bonds are those bonds which are formed by sharing of electrons between two atoms. It is also known as molecular bond. Here in this article we are going to discuss sigma and pi bonds which are covalent bonds only. And also will discuss what is sigma and pi bond, difference between pi bond and sigma bond.

 

What is Sigma Bond? 

The strongest covalent bond which is formed by the head on overlapping atomic orbitals is called sigma bond. It is denoted by σ . We find sigma bonds in Alkanes, Alkenes, Alkynes. Formation of sigma bond is given below between the orbitals - 

 

What is Pi Bond? 

The covalent bond which is formed by lateral overlapping of the half-filled atomic orbitals of atoms is called pi bond. It is denoted by π. We find pi bonds in alkenes and alkynes. Formation of pi bond is given below between the two orbitals - 

 

Difference Between Pi and Sigma Bonds

S.No. 

Sigma Bond 

Pi bond 

1. 

    Covalent bond which is formed by the head on overlapping atomic orbitals is called sigma bond.

Covalent bond which is formed by lateral overlapping of the half-filled atomic orbitals of atoms is called pi bond.

2. 

It is the strongest covalent bond. 

It is weaker than a sigma bond. 

3. 

It is denoted by σ .

It is denoted by π .

4. 

In sigma bonds, overlapping orbitals can be pure orbitals, hybrid orbitals and one hybrid and one pure orbital. 

In pi bond, overlapping orbitals are always pure orbitals only. Pure orbitals are unhybridized orbitals. 

5. 

It can exist independently. Example -alkane.

It can exist with a sigma bond only. Example- alkene and alkyne. 

6. 

It allows free rotation of orbitals. 

It restricts free rotation of orbitals. 

7. 

Atoms with sigma bonds are highly reactive. 

Atoms with pi bonds are less reactive than atoms having sigma bonds only. 

8. 

It has cylindrical charge symmetry around the bond axis. 

There is no symmetry in pi bonds. 

9. 

It determines the shape of the molecule. 

It doesn’t determine the shape of the molecule. 

10. 

Example – CH4  

Example – C2H4