Stability of the species Li2, Li2– and Li2+ increases in the order of :

Li2 = kkσ2s2 Bond order = Li2 > Li+2 = Listability order  Li2>Li2+>Li2-when two molecular species have same bond order then the species with maximum number of electrons in antibonding molecular orbitals is less stable. Number of ABMO electrons in Li2-= 3Number of ABMO electrons in  Li2+= 2