difference between a sigma and pi bond
A sigma bond is the end-to-end overlap of the bonding orbitals, usually hybrid orbitals. The sigma bond is a single bond. A pi bond is the side-to-side overlap of unhybridized p-orbitals. A pi bond, along with a sigma bond form a double bond. A triple bond is two pi bonds and a sigma bond. Take a look at this diagram showing a sigma bond and a pi bond, forming a single bond and a double bond. http://metafysica.nl/ethylene01.jpg.