Sigma bond and Pi bond

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Sigma bond
The bond which is formed by end to end  or axial overlapping of orbitals are called Sigma Bond.

Its bonding orbital consists of a single electron cloud symmetrical about inter nuclear axis.

Since, the overlapping along the axis is maximum, the bond formed is strong.

• Sigma-electrons are reffered as localized.
• Sigma-electrons are less reactive.
• Sigma bond can have independent existance.
• Groups or atoms with small size attached to it are torsially rotated about sigma-bond.
• Sigma-bonds help to determine the shape of molecule.

Pi-Bond

It is a weak covalent bond formed by side wise or lateral overlapping.

Pi bond is weak because of lateral overlapping of orbitals. The bonding consists of two electron clouds - one above and other below the plane of participating atoms.

• Pi-electrons are referred as delocalized.
• Pi-bonds are more reactive.
• Pi-bonds always exists with Sigma bonds.
• Groups or atoms attached to it are not rotated about this bond.
• Pi bonds does not effect the shape of the molecule.
• It is formed by pure orbitals.

How to find the pi and sigma bond in structures.

Sigma-bond -  The first bond made with any other atom. They are made from hybridized orbitals.

Pi-bond - Any 2nd or 3rd bond made with any other atom. They are made from left over p-orbitals.