A pi bond
is a type of bond that is related to the p orbital
s of an atom
. A normal (sigma bond
) bond is a direct interaction between the orbitals of two atoms. However, how can an atoms have more than one bond, such as carbon
which can create a triple bond
, when the other p orbitals are pointing away? The answer is the pi bond, which is a bond between two parallel
p orbitals in each bond.
Best pictured as the blank space between the vertical lines being the atoms, the horizontal lines are the bond. While it looks like there's two bonds, the pi bond has bands of dense electron probability, but is really considered one bond. The second pi bond can come from the p orbital that is perpendicular to the original pi bond, but on the same place, rather than the plane of the sigma bond.
The pi bond leads one to the idea of resonance.
And example and picture of pi bonds can be found here: http://www.uoregon.edu/~ch111/L30.htm
One should also travel to Hybrid Electron Orbitals for an example of more hot electron bonding action.
Source: Mostly myself.