1. The problem statement, all variables and given/known data What is the third ionization energy of Li in its ground state? A. 4.91 E-18 J B. 6.54 E-18 J C. 7.79 E-18 J D. 9.20 E-18 J E. 1.96 E-17 J 2. Relevant equations Maybe: EN=-(2.18E-18)(Z2/N2) 3. The attempt at a solution Plugging in values doesn't give me any of the answers. At first I thought Z was the number of electrons, but now I think it is the atomic number. Either way, I'm at a loss for this question.