Part 3. sp
Hybridization of Carbon
sp2 hybridization is best illustrated
using ethylene, C2H2. The carbon atoms in
this molecule are sp hybridized.
- Note that each carbon now has only two bonds, and that
the bonds about each carbon atom are colinear, with 180o
bond angles throughout. Note also that the C-C bond is a triple
bond, i.e. 6 electrons.
- To make these bonds, the s orbital and one of the p
orbitals of carbon are hybridized to form two equivalent
sp hybrid orbitals. (Remember for now that this leaves
two p orbitals of each carbon un-used.) Each sp orbital
looks like the following. It may not at first glance
appear to be very different from the sp3 or sp2
hybrids, but it does have less p character and more s
character than the others. Use the
mouse to rotate the figure.
- When the two sp hybrids are arranged around the carbon
nucleus, we have:
- To form the C-C bond, an sp 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 two sp hybrids are used
to make single bonds with the hydrogens.
Remember those left over p orbitals on each carbon atom? These
now overlap to produce two pi bonds between the carbon atoms.
These pi bonds and the C-C sigma bond constitute the triple bond
between the carbons. Note the extra electron density between the
Back to Part 2, sp2
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