Its well-known that crystal field splitting occurs because the electrons in d orbitals repel incoming ligands and the d orbitals are no longer degenerate.
My question is now: is the repulsion (with the incoming ligands) between the electrons in the d orbitals or the orbitals itself? If its the former,then does Sc3+ not undergo d orbital splitting ie it exists as 5 degenerate 3d orbitals?
The answer to this question is quite obvious, an orbital has no physical meaning, it's a mathematical object, an electron is a physical charge particle. An occupied orbital is therefore the state of the electron, an empty orbital is a virtual state. Virtual orbitals are useless, have no meaning and are used for convenience to understand things like transitions, the available states and so on. Sc$^{3+}$ has only unoccupied virtual $d$ orbitals, which cannot be split by a crystal field.
