Question

Which is more paramagnetic, Fe²⁺ or Fe³⁺? Give reasons.

Answer 1

1. The Fe²⁺ ion is more paramagnetic than the Fe³⁺ ion because it has more unpaired electrons.
2. Fe²⁺ (d⁶) in hexaaquairon(II) complex has 4 unpaired electrons due to weak field water ligands, making it high spin and strongly paramagnetic.
3. Fe³⁺ (d⁵) in hexacyanidoferrate(III) complex has only 1 unpaired electron because CN⁻ ligands are strong field ligands, causing electron pairing (low spin).
4. More unpaired electrons in Fe²⁺ mean stronger paramagnetism compared to Fe³⁺ with fewer unpaired electrons.

Thus, Fe²⁺ is more paramagnetic than Fe³⁺ due to a greater number of unpaired electrons in typical complexes.