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Question #44261

Difficulty: 8/10 | 🟢 Free

The Question

Chromium (Cr, $Z=24$ ) and Tungsten (W, $Z=74$ ) are Group 6 transition metals. While Cr adopts an anomalous ground-state electronic configuration to maximize exchange energy, W deviates from this expected group trend due to the relativistic contraction of its orbitals. Based on its actual ground-state electronic configuration, determine the spin-only magnetic moment ( $\mu_s$ in BM) of an isolated gaseous Tungsten atom and the total number of electrons present in its outermost $s$ -orbital.

Options

A.
$4.90 \text{ BM}, 2$
B.
$6.93 \text{ BM}, 1$
C.
$4.90 \text{ BM}, 0$
D.
$5.92 \text{ BM}, 1$

Check Your Answer

Correct Answer

Step-by-Step Solution

Explanation

How the Examiner Thinks

Exception_Exposure

Learn to identify edge cases and boundary exceptions that JEE examiners hide in math problems.

Concepts Behind This Question

Hund’s Rule of Maximum Multiplicity|Variable Oxidation State Stability|d-orbital contraction

Why This Question Is Tricky

Common Mistakes

The question tests the 'Chemical Exception' of electronic configurations in the 5d transition series.

Students typically apply Hund's rule of maximum multiplicity to predict a half-filled d5 configuration for Group 6 elements, as seen in Chromium.

However, they overlook the 'Hidden Variable' of relativistic effects in post-lanthanoid elements.

The relativistic contraction of the 6s orbital and the expansion of the 5d orbitals increase the 6s to 5d promotion energy, overriding the exchange energy stabilization.

This makes the textbook prediction fail, trapping students into choosing the 5d5 6s1 configuration.

Quick Facts About This Question

Question Information

Subject	Chemistry
Chapter	Structure of Atom - Class 11 Part 1
Concept	Hund’s Rule of Maximum Multiplicity
Difficulty	8
Cognitive Load	7
Target Solve Time	160 sec
Access	Free