Covalent bonds are formed by overlapping of atomic orbitals. The bond parameters viz. bond length, bond angle, bond enthalpy, etc. depend a lot upon the way the overlapping of atomic orbital takes place. There are majorly two ways in which the overlapping of atomic orbital takes place leading to the formation of two types of bond – Sigma Bond and Pi Bond.
- Sigma Bond (σ)
This type of covalent bond is formed by head-on positive (same phase) overlap of atomic orbital along the internuclear axis. This kind of overlapping is known as axial or head-on overlapping. Sigma Bond is the single bond formed during chemical combination. This can be formed in some of the following combination of atomic orbitals:
- S-S Overlapping
In this kind of overlapping, one s orbital from each participating atom undergoes head-on overlapping along the internuclear axis. S orbital should be half filled before undergoing overlapping.
- S-P overlapping
In this kind of overlapping, one half filed s orbital overlaps with another half-filled p orbital from along the inter-nuclear axis to form a bond.
- P-P overlapping
In this kind of overlapping, one half filled p orbital from each participating atom undergoes head-on overlapping along the internuclear axis.
- Pi Bond(π)
This type of covalent bond is formed by sidewise positive (same phase) overlap of atomic orbital along the perpendicular direction to the internuclear axis. In the formation of π bonds, atomic orbital’s axis is parallel to each other and overlapping is perpendicular to the internuclear axis. Pi Bond is the double or triple bond formed during chemical combination. The orbital formed by sidewise overlapping of atomic orbital consists of two saucer type electron clouds above and below the plane of the two participating atoms.
For more information about Sigma and Pi bonds and their interactive visuals, download Byju’s learning app from play store or app store.
Practise This Question