Hydrocarbon structures and isomers
Hydrocarbons are diverse!
Branching, multiple bonds, and rings in hydrocarbons
- Ethane (), with a single bond between the two carbons, adopts a two-tetrahedron shape (one tetrahedron about each carbon). Importantly, rotation occurs freely about the carbon-carbon bond.
- In contrast, ethene (), with a double bond between the two carbons, is planer (all of its atoms lie in the same plane). Furthermore, rotation about the carbon-carbon double bond is restricted. This is a general feature of carbon-carbon double bonds, so anytime you see one of these in a molecule, remember that the portion of the molecule containing the double bond will be planar and unable to rotate.
- Finally, ethyne (), with a triple bond between the two carbons, is both planar and linear. As with the double bond, rotation is completely restricted about the carbon-carbon triple bond.