Theoretical Question: third ionization energy

[medemic]

Here's a question for y'all...we are taught that second ionization energy is always greater than the first. Fine. Logical would follow that third ionization would be greater than the second and the first due to electrostatics. But, lets take iron for example and compare the ionization energies. The first electron would be the 4s2, and we could predict this would take a good deal of energy since the orbital is filled and stable. What about the second ionization energy? Would this be less or greater since the atom is unstable with only one electron in the s orbital? One step further, what about the third ionization energy. The third ionization energy would be removing the 3d6 electron, allowing the atom to become more stable since it would have all the d orbitals half filled. My question is...predict the first second and third ionization energies for iron. Does it follow the general trend where first IE<second IE< third IE?

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[QrtrLifeCrisis]

Regardless of the the stability gained from half-filled or filled orbitals, IE1 < IE2 < IE3 will always be true.

Electrostatics consideration > Filled/half-filled orbitals.

 

[FeinMS]

I get what you're saying though. I was thinking like that in the beginning. I think another explanation is that when you remove an electron to make cation, ionic size decreases, so the rest of electrons are much closer to the nucleus than before. So it follows that the next electron is harder to remove.

 

[medemic]

K thanks guys.