Ionisation energy of He+ is 19.6 × 10–18J atom–1. The energy of the first stationary state of Li2+ is

IP1 of He+ = 19.6 × 10-18 JIP of one electron species = E1 Z2IPHe+IPLi+2=2232IPLi+2=9419.6×10-18          = 4.41 × 10-17 J/atomMagnitude of IP1 = Magnitude of energy of electron in first orbitEnergy of e- in first orbit of Li+2 = - 4.41 × 10-17 J/atom