12 Difference Between Sigma Bond(σ) And Pi Bond(π)

There are two types of overlapping orbitals, that is, sigma (σ) and Pi (π). Both bonds are formed from the overlap of two orbitals, one on each atom. Sigma bonds occur when orbitals overlap in an end-to-end fashion, with the electron density concentrated between the nuclei of the bonding atoms also referred to as the internuclear axis.

Pi bonds occur when orbitals overlap in a side-by-side fashion with the electron density concentrated above and below the plane of the nuclei of the bonding atoms. By occupying the region of space that is above, below, and on the sides of an atom’s nuclei, two pi bonds can form.

Both types of overlapping orbitals can be related to bond order. Single bonds have one sigma bond. Double bonds consist of one sigma and one pi bond while triple bonds contain one sigma and two pi bonds.

Sigma Bond(σ)

Characteristics Of Sigma Bond

• Sigma bond is formed as a result of an end to end overlap i.e head-on collision of atomic orbitals.
• The bond is rotationally symmetrical about the internuclear axis.
• Sigma bonds are formed first when atoms interact.
• Sigma bonds are stronger bonds due to a greater extent of overlapping.
• It can be formed between any two orbitals i.e s-s, s-p or p-p etc.
• Sigma bonds are more reactive.
• It determines the direction of the bond, internuclear distance and shape of the molecule.
• Sigma bonds are involved in the control of geometry in polyatomic molecules.
• Bond energy is more.
• It results in high electron density between two nuclei on internuclear axis.
• Pure and hybrid orbitals can form sigma bonds.
• The lobe participating in the overlapping is stretched and the other lobe is reduced.
• The relativity of the compound formed is inversely proportional to some sigma bonds whereas the stability of the compound is directly proportional to the number of sigma bonds.

Pi Bond(π)

Characteristic Of Pi Bond

• Pi bond results from the formation of a molecular orbital by the end-to-end overlap of atomic orbitals along a plane perpendicular to a line connecting the nuclei of the atoms.
• The bond is not rotationally symmetrical about the internuclear axis.
• Pi bonds are formed after the formation of sigma bonds.
• Pi bonds are usually very weak due to the lower extent of overlapping.
• It can be formed only between ‘p’ orbitals.
• Pi bonds are less reactive.
• It does not affect the direction of the bond, internuclear distance and shape of the molecule.
• Pi bonds are not involved in the control of geometry in polyatomic molecules.
• Bond energy is less.
• The bond is not rotationally symmetrical about the internuclear axis.
• Only pure orbitals can form Pi bonds.
• Both the lobes take part in bonding and remain the same in size.
• The relativity of the compound formed is directly proportional to some Pi bonds whereas the stability of the compound is inversely proportional to the number of pi bonds.

Difference Between Sigma Bond(σ) And Pi Bond(π) In Tabular Form