Molecular nitrogen is a diatomic molecule - N2. Atomic nitrogen has an atomic number of 7 and an electron configuration of 1s2, 2s2, 2p3. Following the Aufbau Principle and Hund's Rule the electrons in the 2p half-fill each of the px, py and pz configurations. This gives atomic nitrogen the ability to form three covalent bonds. In this case nitrogen is bonding to itself so there is no difference in electronegativity and the bond will be purely covalent. The px orbital forms a sigma bond with the px of the other nitrogen. The other two - the py and pz - form pi bonds with the corresponding orbitals from the other nitrogen atom. This gives molecular nitrogen one unshared pair and three shared pairs of electrons in each atom. This results in a triple bond - probably the strongest covalent bond of all. It gives molecular nitrogen its characteristic unreactivity in the atmosphere. Except for certain nitrogen fixing bacteria and lightning bolts, virtually nothing can break this bond.
