Question

Explain the paramagnetic behaviour of transition metal ions.

Answer 1

1. Transition metal ions show paramagnetism due to the presence of unpaired electrons in their (n − 1)d orbitals.
2. The number of unpaired electrons increases from one to five across a transition series, so paramagnetism increases and is maximum in the middle of the series.
3. Magnetic moment, a measure of paramagnetism, depends on the number of unpaired electrons.
4. An unpaired electron acts like a tiny magnet because its spinning and orbital motion generate a magnetic field.
5. Electrons paired with opposite spins cancel each other’s magnetic field, so ions with all paired electrons are diamagnetic (no paramagnetism).
6. The magnetic moment (in Bohr magneton units) for transition metal ions can be calculated using the formula: μ = `sqrt[n(n+2)]`, where n is the number of unpaired electrons.

Therefore, ions with more unpaired electrons show stronger attraction to magnetic fields, exhibiting paramagnetic behavior.