How Do You Define a Pi Bond in Chemistry

A pi bond (Ï€ bond)  is a covalent bond  formed between two neighboring atoms unbonded p-orbitals. An unbound p-orbital electron in one atom forms an electron pair with a neighboring atoms unbound, parallel p-orbital electron. This electron pair forms the pi bond. Double and triple bonds between atoms are usually made up of a single sigma bond and one or two pi bonds. Pi bonds are generally denoted by the Greek letter Ï€, in reference to the p orbital. The symmetry of a pi bond is the same as that of the p orbital as viewed down the bond axis. Note d orbitals also form pi bonds. This behavior is the basis of metal-metal multiple bonding.