Question

What is the effective nuclear charge of the following?

F-
Na+

I know that for F- it is 9-7=2
and for Na+ it is 11-2=9, but what about the charges??

I don't understand what effect do the charges make?

If 9-7 then isn't it just simply F and not F-? Similarly, if 11-2 then isn't it just simply Na and not Na+??

Answer 1

I think you are confused with the definition. Here is a site that gives you the effective nuclear charge for Na^+ and F^-.
Zeff = #protons -#inner electrons = ?
For Na^+ that is 11-2 = 9+.
For F^- that is 9- 2 = 7+.
https://www.google.com/search?q=effective+nuclear+charge&ie=utf-8&oe=utf-8