In crystal field theory, how are anionic ligands treated?

The correct answer is Option (2) → As negative point charges

Crystal field theory is an electrostatic model: it takes the metal–ligand bond as ionic, arising only from attraction and repulsion of charges. An anionic ligand such as \( \ce{Cl^-} \) or \( \ce{F^-} \) is therefore treated as a point charge, and since it is an anion that charge is negative.

Why the other options are incorrect

Option (1) As positive point charges — Incorrect. An anion carries a negative charge; the negative field of the ligands is what repels the metal d electrons and splits the d orbitals.

Option (3) As point dipoles — Incorrect. Point dipoles are used for neutral molecules such as \( \ce{NH3} \) and \( \ce{H2O} \), whose negative ends face the metal.

Option (4) As electron-pair donors forming covalent bonds with the metal — Incorrect. This is the picture of valence bond theory, where ligand electron pairs enter the metal’s hybrid orbitals; crystal field theory treats the bond as purely ionic.

NCERT (2026-27 edition):
5.5.4 Crystal Field Theory – “The crystal field theory (CFT) is an electrostatic model which considers the metal-ligand bond to be ionic arising purely from electrostatic interactions between the metal ion and the ligand. Ligands are treated as point charges in case of anions or point dipoles in case of neutral molecules.”