Ions Sizes QuestionWatch
I'm having trouble ordering the following ions in order of size of radius:
La^(3+), Eu^(3+), Gd^(3+), Yb^(3+).
If we were to disregard the ionization and consider the atoms, we'd get
La > Eu > Gd > Yb, since La is farthest to the left in the periodic table etc...
But when the atoms are ionized, it seems to me that only La would loose all the electrons in its outer shell when we consider La^(3+) and reach noble gas configuration [Xe]. Thus, according to my thinking, La^(3+) may be smaller in size than Eu^(3+). However, the answer to the question should be:
La^(3+)> Eu^(3+)> Gd^(3+)> Yb^(3+).
Could someone please help understand how we can get to this conclusion?
Also, I'm not sure if my notation is correct/appropriate for this forum, so comments on that too would be highly appreciated.
Thanks in advance,
Also, regarding your comment about La^3+ being smaller than Eu^3+, this is very unlikely given that Eu is towards the centre of the period so will have a much higher nuclear charge, causing the ion’s orbitals to be more contracted giving a smaller radius. Even with La^3+ compared to Ce^3+ there is a decrease, probably do to the poor shielding of the 4f orbitals causing the effective nuclear charge to increase rapidly which reduces the ion size.
If anyone thinks this is wrong/has missed points please correct me!