D

Double Bond

σ bond (head-on) + π bond (lateral)
Quick Reference
Formula / Notationσ bond (head-on) + π bond (lateral)
Also Known AsSigma bond, Pi bond, Single bond, Double bond, Triple bond

What is Double Bond?

A covalent bond formed when two atoms share two pairs of electrons, consisting of one sigma bond and one pi bond. Double bonds are shorter and stronger than single bonds but allow less free rotation. They are found in alkenes and carbonyl compounds.

Formula & Notation

σ bond (head-on) + π bond (lateral)

Other Names / Synonyms: Sigma bond, Pi bond, Single bond, Double bond, Triple bond

Properties & Characteristics

Single bond = 1σ. Double bond = 1σ + 1π. Triple bond = 1σ + 2π. Sigma bonds: direct overlap along internuclear axis — free rotation allowed. Pi bonds: lateral overlap above and below — no free rotation (explains cis/trans isomerism in alkenes). Bond energies: C−C = 347, C=C = 614, C≡C = 839 kJ/mol. Bond order increases: shorter bond, higher energy, more restricted rotation.

Uses & Applications

Foundation of organic chemistry molecular structure. Double bonds enable electrophilic addition reactions (alkenes). Triple bonds reactive to both addition and substitution (alkynes). Conjugated π systems: aromatic stability (benzene), color of organic dyes (extended conjugation), photovoltaic materials. Peptide bond partial double-bond character restricts protein backbone conformation.

Safety Information

Molecules with many π bonds tend to be more reactive and potentially more flammable. Peroxides contain weak O−O single bonds prone to homolytic cleavage — explosion hazard. Aromatic compounds (benzene, toluene) with delocalized π systems are generally toxic (carcinogenic) — handle in fume hood with respiratory protection.

Always consult the SDS/MSDS before handling any chemical. This information is for educational purposes only.

Key Facts

Term Double Bond
Formula σ bond (head-on) + π bond (lateral)
Synonyms Sigma bond, Pi bond, Single bond, Double bond, Triple bond

Frequently Asked Questions

A covalent bond formed when two atoms share two pairs of electrons, consisting of one sigma bond and one pi bond. Double bonds are shorter and stronger than single bonds but allow less free rotation. They are found in alkenes and carbonyl compounds.

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