BRAINCAKEBonding
A C=C double bond is made of two different kinds of covalent bond: one sigma (σ) bond and one pi (π) bond.
The σ bond forms by direct (end-on) overlap of orbitals, so its electron density lies on the line between the two carbon nuclei. Each carbon of the C=C forms three σ bonds, and these lie in one plane at 120° to each other, so the arrangement around each carbon is trigonal planar.
Each carbon also has one p orbital left over, at right angles to that plane. The π bond forms by sideways overlap of these two p orbitals. Its electron density sits in two regions, above and below the plane of the molecule.
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More in Alkenes
- General Formula
- Naming Alkenes
- Position Isomerism
- Geometric Isomerism
- Nomenclature (Cahn-Ingold-Prelog)
- Physical Properties of Alkenes
- Combustion
- Electrophiles
All 23 lessons in Alkenes · All AQA AS-level Chemistry topics