Most single bonds are sigma bonds (σ-bond). In the valence bond theory, a sigma bond is a valence bond that is symmetrical around the imaginary line between the bonded atoms.
Generalic, Eni. "Sigma bond." Croatian-English Chemistry Dictionary & Glossary. 29 June 2022. KTF-Split. {Date of access}. <https://glossary.periodni.com>.
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