ABSTRACT
Both the σ-bonds and the π-bonds are pure covalent bonds, and their nature has been studied for decades prior to the discovery of graphene due to their wider importance in organic chemistry [1]. To understand their nature, we begin with a description of molecular orbital theory (applying it to the simplest possible molecule, the hydrogen molecule-ion). We will then apply molecular orbital theory to the bonding in graphene and diamond. The comparison between the interatomic bonding in graphene and diamond is instructive in several ways.
