Q1(j). Magnetism of vanadium ions

Answer in brief

V³⁺ is [Ar]3d² and normally has two unpaired electrons; V⁵⁺ is [Ar]3d⁰ and has none.

Key points

• Vanadium has Z = 23 and neutral configuration [Ar]3d³4s²; remove 4s electrons before 3d electrons when forming these ions.
• V³⁺: remove two 4s electrons and one 3d electron to obtain 3d²; in an octahedral field the two electrons occupy separate t₂g orbitals.
• Two unpaired electrons give paramagnetism; μso = √(2(2 + 2)) = 2.83 μB.
• V⁵⁺: removal of all five valence electrons gives 3d⁰; no unpaired electrons remain, so it is diamagnetic.