the potential energy of electron present in the ground state lithium ion+2 can be represented as

As the potential energy is twice of total energy so potential energy of electron in ground state of hydrogen is -27.2 and as energy of proportional to Z²/n². So for lithium is -244.8 MeV.Hope it clears. If u have doubts then please clearify. And if u like my answer then please approve answer

We assume under the Born-Oppenheimer approximation that the nucleus can be treated as nearly stationary, so that the net charge of it is Z⋅e .You know the atomic number of Li is 3 . So...ˆVLi2+=−3e24πε0→r