For atoms, we obtained electronic configurations by writing them as 1s2 2s1, 1s2 2s2 2p5 and so on. The principles used in filing the orbitals were the aufbau principle and the Pauli exclusion princilple. For MOs too, similar procedure is used with the labels for MOs being 1, 2 or , , and so on where the subscript indicates the atomic orbitals used in the MO and the integer on the left is the label or the index of the MO. The electronic configurations of the first and second row diatomics are given in Table 1. Also included in the Table are the number of bonding and antibonding electrons in each molecule, the bond order, the binding energy and the bond length.