Question

The spin only magnetic moment of a divalent ion in aqueous solution (atomic number 29) is ________ BM.

Hint:

The formula for spin-only magnetic moment is $\mu = \sqrt{n(n+2)}$ BM. Memorize the values for n=1 to 5: n=1, $\mu$=1.73; n=2, $\mu$=2.83; n=3, $\mu$=3.87; n=4, $\mu$=4.90; n=5, $\mu$=5.92 BM. Notice the value is always slightly less than n+1.

Answer 1

Correct Answer: 2

Q59. Atomic number 29 $\Rightarrow$ Copper (Cu). Step 1: Electronic configuration \[ \mathrm{Cu^{2+}} : [Ar]\,3d^9 \] Step 2: Number of unpaired electrons \[ n = 1 \] Step 3: Spin-only magnetic moment \[ \mu = \sqrt{n(n+2)} = \sqrt{3} \approx 1.73\text{ BM} \] \[ \boxed{1.73} \]