[kinslow135]

Hi, i need to know why the Ce(IV) oxidation state is especially stable, and also the Eu(II) and Yb(II) state as opposed to the rest of the lanthanides that generally only have the III oxidation state available, why is this?  It looks like the 4f5d6s would all be emptied out to make it like xenon, but what significance does this heave?  the 4f and 5d both have one so i guess they won't be repelled?

[kriggy]

If the orbitals are full/empty or half filled it increases the stability of the ion. That is the case of Ce(IV) - 4f0, 5d0, 6s0, Eu(II) 4f7 5d0, 6s0 and Yb(II) 4f14, 5d0 6s0.