Rn: [Xe] 4f15 5d10 6s2 6p6?
That would just be the wrong number of electrons. You can only fit 14 into 4f.
La has 4f0
, Lu has 4f14
Periodic tables vary; some have La below Y (in the d block) with Ce-Lu separate, as the f block, while some have La-Yb separate, with Lu below Y (then all the 3rd row transition metals have 4f14
). Some, like www.ptable.com
, have La-Lu separate, illogically suggesting a 15-element f block. I prefer the first style.