Question

Calculate the ‘spin only’ magnetic moment of a divalent ion of a metal M in aqueous solution. The atomic number of the metal M is 25.

Hint:

Spin-only magnetic moment depends on unpaired electrons:
\(\mu = \sqrt{n(n+2)}\), where \(n =\) number of unpaired electrons.

Answer 1

Step 1: Atomic number of M = 25 → Mn
Mn: [Ar] 3d⁵ 4s²
Step 2: In divalent state (Mn²⁺): loses two electrons → 3d⁵ configuration
Step 3: Number of unpaired electrons \(n = 5\)
Step 4: Magnetic moment (spin only):
\[\mu = \sqrt{n(n+2)} = \sqrt{5(5+2)} = \sqrt{35} \approx 5.92 \, \text{BM}\]