Junior Class 1 Answered

The ligand's electrons interact with the electrons of the d orbitals, the electrostatic interactions cause the energy levels of the d-orbital to fluctuate depending on the orientation and the nature of the ligands. For example, the oxidation state and the strength of the ligands determine splitting; the higher the oxidation state or the stronger the ligand, the larger the splitting.

Ligands are classified as strong or weak based on the spectrochemical series:

I^- < Br^- < Cl^- < SCN^- < F^- < OH^- < ox^2-< ONO^- < H₂O < SCN^- < EDTA^4- < NH₃ < en < NO₂^- < CN^-