Chemistry Transition Elements BUMHS 2022
PMDC Verified Question 34 of 68
The outer shell electronic configuration of transition block elements is give by
A
\( (n-1)d^{1-10} \; ns^{2} \)
B
\( (n-1)d^{1-10} \; (n-1)s^{0-2} \)
C
\( (n-1)d^{1-10} \; ns^{0-2} \)
D
\( nd^{1-10} \; ns^{0-2} \)
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option A: \( (n-1)d^{1-10} \; ns^{2} \)
Concept:

The general electronic configuration represents how valence electrons fill the ultimate and penultimate shells across the transition metals.

Solution:

  • For most standard transition elements (Group IIIB to IIB), electrons fill the \(ns\) orbital and then sequentially fill the \((n-1)d\) orbitals.


  • The vast majority have 2 electrons in the \(s\)-orbital, yielding a general formula of \((n-1)d^{1-10} \; ns^2\).


  • Note: While anomalies like Cr and Cu have \(ns^1\), and Pd has \(ns^0\) (making \(ns^{0-2}\) technically more exhaustive for the whole block), \((n-1)d^{1-10} \; ns^2\) is the accepted textbook standard generic form tested here.


Why other options are incorrect:

  • Option D: Incorrectly states \(nd\). It must be \((n-1)d\) because the \(d\)-subshell is always one principal quantum number lower than the valence \(s\)-subshell.

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