[Winga]

e.g.1

H atom vs F atom:
About their AOs in HF MO diagram, the energy level of F 2p orbitals is lower than that of H 1s orbital. So, does it imply that F atomic size is smaller than H atomic size?


e.g.2

For transition metal ions, Fe³⁺ vs Ru³⁺
Is it possible that the energy level of Ru 4d orbitals lower than that of Fe 3d orbitals due to increasing Zeff down the group?

[Major Werner]

Winga, it is not possible for hydrogen to have a larger atomic size than fluorine just for the mere fact that the belong to different periods. hence, the flurine atom will have two shells instead of one, thus proving that it is higher in atomic size as compared t thehydrogen atom.

Also the 4d orbitals of Ru are expected to be higher in energy than the 3d orbitals despite the fact that Zeff increases down the group.