Hybrid Orbitals

Part 2. sp2 Hybridization of Carbon

sp2 hybridization is best illustrated using ethene, C2H4. The carbon atoms in this molecule are sp2 hybridized.


Note that each carbon now has only three bonds, and that the bonds about each carbon atom are coplanar, with 120o bond angles throughout. Note also that the C-C bond is a double bond, i.e. 4 electrons.
To make these bonds, the s orbital and two of the p orbitals of carbon are hybridized to for three equivalent sp2 hybrid orbitals. (Remember for now that this leaves one p orbital of carbon un-used.) Each sp2 orbital looks like the following. Use the mouse to rotate the figure.

When the three sp2 hybrids are arranged around the carbon nucleus, we have:
To form the C-C bond, an sp2 hybrid from one carbon atom overlaps with that of the other, creating a C-C single bond. This type of bond, resulting from the end-on interaction of the two hybrid orbitals, is termed a "sigma" bond. The other four sp2 hybrids are used to make single bonds with the hydrogens.

Remember that left over p orbital on each carbon atom? These two now overlap to produce another bond between the carbon atoms. This "pi" bind and the C-C sigma bond constitute the double bond between the carbons. Note the extra electron density between the carbons.

Cool, eh?

Back to part 1,sp3 hybridization

On to part 3, sp hybridization

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