Calculate the magnetic moment (spin-only) of a trivalent ion in aqueous solution if its atomic number is 22.

1.73 BM

The correct answer is Option (2) → 1.73 BM

Atomic number 22 → Titanium (Ti)

Electronic configuration of Ti:

$\text{Ti} = [Ar]\,3d^2\,4s^2$

For Ti³⁺ (trivalent ion):  three electrons are removed.

• Loses 2 electrons from 4s and 1 from 3d

$\text{Ti}^{3+} = [Ar]\,3d^1$

So, number of unpaired electrons:

$n = 1$

Spin-only magnetic moment:

$\mu = \sqrt{n(n+2)} = \sqrt{1(1+2)} = \sqrt{3} \approx 1.73 \text{ BM}$