Coulomb Energy in the KI Molecule: Solving for Separation Distance

[mateomy]

The ionization of potassium is 4.34 eV; the electron affinity of iodine is 3.06 eV. At what separation distance will the KI molecule gain enough Coulomb energy to overcome the energy needed to form the K^+ and I^- ions?

I'm looking at the solution to this problem and I'm not understanding how they get the Coulomb energy. Is it just the
<br /> E_n=\frac{-Z^2 (13.6eV)}{n^2}<br />
equation? I'm not getting the same numbers they're getting so I think I'm confused on the definition of Coulomb energy. Can someone clarify it for me. I understand the Coulomb repulsion/attraction is what I've seen over and over again from electrostatics...but I don't see how to tie that into this problem. Specifically because I don't know the radius of the particular ions.

They're getting values of 3.06 and 4.34 eV

Please and Thanks.

 

[mateomy]

Ugh, nevermind. My brain is fried...I figured it out.