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How do alkanes differ from alkenes?
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organic compound
The structures of organic compounds can be depicted in condensed, expanded, and three-dimensional structural formulas.
Alkanes and alkenes are both types of aliphatic hydrocarbons, but they differ fundamentally in their chemical structure and reactivity.1
Structural Differences
- Bonding: Alkanes consist entirely of carbon and hydrogen atoms joined by single sigma (σ) bonds. In contrast, alkenes contain at least one carbon-carbon double bond, which consists of one sigma bond and one pi (π) bond.23145
- Geometry: Alkanes are characterized by three-dimensional structures with tetrahedral geometry around each carbon atom. Alkenes, however, feature a planar arrangement for the two carbon atoms involved in the double bond and the four atoms attached to them.6345
Chemical Properties
- Saturation: Alkanes are described as saturated hydrocarbons because they contain only single bonds and cannot undergo addition reactions to increase the number of sigma bonds. Alkenes are considered unsaturated because their pi bond can react with electron-deficient species, leading to the rupture of the pi bond and the formation of two new, stronger sigma bonds.145