Hey all, This is a problem I can't really wrap my head around. 1.) The lanthanoid series is formed through the progressive filling of the 4f subshell, whereas the first row transition metal series is formed through the progressive filling of the 3d subshell. a) What is the relative magnitude of crystal field splitting energies for metal ion complexes within each of these series? Explain the reason for any difference. Attempt at Solution: In my notes I've written that since the lanthanides are formed through the progressive filling of the 4f subshell, these electrons in the f-orbitals are much more tightly held/embedded in the nucleus. Hence the crystal field splitting energies are much smaller, almost 100x as small as the d-block. Ligand field splitting energies for 4f: 50 - 100 cm^-1 5f: 1000 - 2000 cm^-1 (Hence there's a 20 fold difference). There is also no Jahn-Teller Distortion for lanthanides.