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Question #44893

Difficulty: 8/10 | 🟢 Free

The Question

The magnetic properties of actinoid complexes deviate significantly from those of 3d transition metals due to strong spin-orbit coupling, which prevents the quenching of orbital angular momentum. Calculate the theoretical effective magnetic moment ( $\mu_{eff}$ ) of the \ce{Pu^{3+}} ion in aqueous solution at 298 K. Assume the magnetic behavior is dictated entirely by its ground state term symbol (Russell-Saunders coupling).

(Given: Atomic number of Pu = 94, $\sqrt{35} \approx 5.92$ , $\sqrt{65} \approx 8.06$ )

Options

A.
0.85 BM
B.
5.92 BM
C.
6.93 BM
D.
8.06 BM

Check Your Answer

Correct Answer

Step-by-Step Solution

Explanation

How the Examiner Thinks

Mechanism_Trap

Don't get tricked by the process! Learn the mechanical traps used in competitive exam questions.

Concepts Behind This Question

Actinoid Oxidation State Variety|Magnetic Moment Quenching|Color and Charge Transfer

Why This Question Is Tricky

Common Mistakes

This question tests the 'Chemical Exception' of magnetic moment calculations in f-block elements, specifically actinoids.

Students often blindly apply the 'spin-only' formula ( $\mu = \sqrt{n(n+2)}$ ), which is valid for 3d metals where the crystal field quenches orbital angular momentum.

However, in 5f actinoids, strong spin-orbit coupling ( $\zeta$ ) dominates over crystal field splitting.

Therefore, the orbital contribution is not quenched, and the total angular momentum $J$ must be used via the Landé g-factor.

Applying the spin-only formula to \ce{Pu^{3+}} ( $n=5$ ) yields the trap answer of 5.92 BM, whereas the true theoretical value is 0.85 BM.

Quick Facts About This Question

Question Information

Subject	Chemistry
Chapter	D and F Block Elements - Class 12
Concept	Actinoid Oxidation State Variety
Difficulty	8
Cognitive Load	7
Target Solve Time	160 sec
Access	Free