sigma star orbital

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July 13, 2026

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A sigma bond is a type of chemical bond where two atoms share an electron pair. This shared pair occupies an orbital located primarily between the two nuclei, with a symmetrical distribution around the line connecting them.1

In molecular orbital theory, a sigma star ((\sigma^)) orbital is an antibonding molecular orbital. It is formed by the destructive interference of atomic orbitals, resulting in a nodal plane between the nuclei. Electrons in a (\sigma^)-orbital are excluded from the internuclear region, leading to a higher energy state compared to bonding orbitals.2

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chemical bonding
Molecular orbitals of H2 and He2
…(and referred to as “sigma star”) or, because it is the second of the two σ orbitals, 2σ.
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…(and referred to as “sigma star”) or, because it is the second of the two σ orbitals, 2σ.
Read More