ionization energy

[Physicsiscool]

Can someone please help me understand the following question?

The ionization energy of the outermost electron in Li is 5.390 eV. What is the effective charge seen by the outermost electron? (Li has 2 energy levels)

[dextercioby]

Can someone please help me understand the following question?

The ionization energy of the outermost electron in Li is 5.390 eV. What is the effective charge seen by the outermost electron? (Li has 2 energy levels)

Think as Litium atom as a hydronenoid ion with one lousy electron orbiting the positively charged core (i don't call it nucleus,since it includes the other 2 electrons of Litium) of charge +Z_eff times e.
Plug it in Balmer formula (the one which assumes infinite mass nucleus and that,for the reason of simplicity) for n_1=2 and n_2=infinity and you'll get your result by a simple division.I would advise using Heaviside-Lorentz units.