Answer to Question #59962 in Engineering for chi

Question

Doubly-ionized lithium is hydrogen-like atom. Atomic ionization energy can be predicted by an analysis using electrostatic potential and the Bohr model of the atom. For this model ionization energy will be:
E= −(Z2 13.6[eV])/n2
where Z - nuclei charge. n - principal quantum number.
So, for Li2+ (Z=3) energy diagram will be something like this:
n=1. E1=-122.4 eV
n=2. E2=-30.6 eV
n=3. E3=-13.6 eV
….....................................
n = infinity E = 0 (vacuum level)
When n=1, corresponded E = 122.4 eV – this is ionization energy for ground state.

why the answer is not E= -122.4eV instead it is E= 122.4eV?