The Li atom has a nucleus with a 3e positive charge, which is surrounded by a full 1s shell with two electrons, and a single valence electron in the outer 2s subshell. The atomic radius of the Li atom is about 0.17 nm. Using the Virial theorem, and assuming that the valence electron sees the nuclear 3e shielded by the two 1s electrons, that is, a net charge of e, estimate the ionization energy of Li (the energy required to free the 2s electron). Compare this value with the experimental value of 5.39 eV. Suppose that the actual nuclear charge seen by the valence electron is not e but a little higher, say 1.25e, due to the imperfect shielding provided by the closed 1s shell. What would be the new ionization energy