Molecular orbitals are formed by the overlap of atomic orbitals . Two atomic orbitals combine to form two molecular orbitals, called Bonding Molecular Orbital (BMO) and Anti - Bonding Molecular Orbital (ABMO). Different atomic orbitals of one atom combine with those atomic orbitals of the second atom which have comparable energles and proper orientation Further, if overlapping is head on, the molecular orbitals is called 'sigma' and if the overlap is lateral, the molecular orbital is called 'pi' . The molecular orbitals are filled with electrons following the same rules as followed for filling of atomic orbitals . However, the order of filling in not the same for of the most important parameter to compare a number of their characteristics H_(2), Li_(2), B_(2) each has bond order equal to 1 . The order of their stability is

H_(2), Li_(2), B_(2) each has bond order equal to 1 the order of their stability is

MO' s are formed by the overlap of A'O s Two AO's combine to form two MO's called bonding molecular orbital (BMO) and antibonding molecular orbital (ABMO) Differnet AO' s of one atom combine with these AO 's of the second atom which have comparable energies and proper orienation Further, If the overlapping is head on, the MO is called 'pi' The MO's are filled with electrons following the same rules as followed for filling of atomic orbitals However the order of filling is not the same for all molecules or their ions Bond order is one of the most important parameter to compare a number of their characteristics H_(2),Li_(2)B_(2) each has bond order equal to 1 The order of their stability is .