Which is stronger, sigma or pi bond?

A sigma bond is stronger because head-on overlap of orbitals is more effective than the sideways overlap of a pi bond.

Can a pi bond exist alone?

No. A pi bond is always accompanied by a sigma bond. A single bond is a sigma bond; a double bond is one sigma + one pi; a triple bond is one sigma + two pi bonds.

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Difference Between Sigma (σ) Bond and Pi (π) Bond

Covalent bonds form when atomic orbitals overlap. The way they overlap decides whether the bond is sigma or pi.

In short

A sigma (σ) bond forms by head-on (axial) overlap of orbitals and is stronger; a pi (π) bond forms by sideways (lateral) overlap of p-orbitals and is weaker.

Sigma (σ) Bond vs Pi (π) Bond — Comparison Table

Basis	Sigma (σ) Bond	Pi (π) Bond
Overlap	Head-on / axial	Sideways / lateral
Strength	Stronger	Weaker
Rotation	Free rotation possible	Restricted rotation
Exists	Independently	Only with a sigma bond
Electron cloud	Along internuclear axis	Above and below the axis
Example	Single bonds (H–H)	Double/triple bonds (C=C)

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Frequently Asked Questions — Sigma (σ) Bond vs Pi (π) Bond

Which is stronger, sigma or pi bond?: A sigma bond is stronger because head-on overlap of orbitals is more effective than the sideways overlap of a pi bond.
Can a pi bond exist alone?: No. A pi bond is always accompanied by a sigma bond. A single bond is a sigma bond; a double bond is one sigma + one pi; a triple bond is one sigma + two pi bonds.

Difference Between Sigma (σ) Bond and Pi (π) Bond

Sigma (σ) Bond vs Pi (π) Bond — Comparison Table

Frequently Asked Questions — Sigma (σ) Bond vs Pi (π) Bond

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