Why is the ionization energy of Vanadium higher than Sodium?

Question

Explain why please. I'm not interested in periodic trends, I want to know why on a basis of electrons, protons, nuclear charge, or whatever may apply.

I was expecting the sodium to have a higher ionization energy because it has a lot less electron shielding than vanadium. You're also a removing an electron (for sodium from the 3s1 layer whereas you're removing one from the 4s2 layer from vanadium. I was expecting it to be harder to remove an electron from 3s1 than it is to remove one from 4s2 due to their proximity to the nucleus.There is also repulsion between the two electrons in the valence 4s2 orbital in Vanadium that makes it easier to pull out.

Why does Vanadium have a higher ionization energy?

Is my reasoning completely false? Please correct me if I am.

Answer 1

You're asking if you're correct that Na has LESS e- shielding than V?

lol.  What do you think!  Sure and although the electrons in V are more shielded they magically act like there is more  energy required for ionization?  Just think about it!

The reason is inner electrons don't do a great job of shielding outer electron (depends on obitals involved, of course).  You are right that there is a balance between e - e repulsion and e - nucleus attraction.  Spin -spin interactions are important determinants in only a couple of cases.