Electronic Configuration of Transition Metals for NEET: Key Points, Tricks & MCQs
Electronic ConfigurationTransition Metalsd and f Block ElementsNEET ChemistryNEET 2025d-block elementsAufbau principle
Electronic Configuration of Transition Metals for NEET: Key Points, Tricks & MCQs
d and f Block ElementsĀ·2 min readĀ·NEET 2026
What NEET Asks
Direct Configuration: Identify correct configurations for atoms and ions, a frequent question type.
Exceptions: Questions on anomalous configurations of Cr and Cu are common and high-yield.
Properties Link: Relate electronic configuration to magnetic properties or stability, often as part of a multi-concept question.
Key Points
General Configuration: The general outer electronic configuration for transition metals is (n-1)dĀ¹ā»Ā¹ā° nsĀ¹ā»Ā². Here, n refers to the outermost shell.
Orbital Filling: Electrons generally fill the ns orbital before the (n-1)d orbitals according to the Aufbau principle.
Electron Removal: When forming cations, electrons are always removed first from the outermost ns orbital, then from the (n-1)d orbital.
Stability Rule: Half-filled (dāµ) and fully-filled (dĀ¹ā°) d-orbitals provide extra stability due to symmetry and exchange energy.
Exceptions (Cr, Cu): Chromium (Z=24) has the configuration [Ar]3dāµ4sĀ¹ (not 3dā“4sĀ²). Copper (Z=29) has [Ar]3dĀ¹ā°4sĀ¹ (not 3dā¹4sĀ²).
Must-Know Formula / Reaction
General Electronic Configuration: (n-1)dĀ¹ā»Ā¹ā° nsĀ¹ā»Ā²
(n-1)d: Represents the penultimate d-subshell, holding 1 to 10 electrons.
ns: Represents the outermost s-subshell, holding 1 or 2 electrons.
Common Mistakes
Students often forget the crucial exceptions for Chromium and Copper, applying the Aufbau principle strictly.
Don't confuse the order of electron filling (Aufbau) with the order of electron removal from ions (always ns first).
Mistakenly removing electrons from (n-1)d before ns when deriving configurations of transition metal cations.
Rapid Revision
Master (n-1)dĀ¹ā»Ā¹ā° nsĀ¹ā»Ā². Crucially, for ions, remove ns electrons first, then (n-1)d. Always remember Cr (3dāµ4sĀ¹) and Cu (3dĀ¹ā°4sĀ¹) exceptions; they're high-frequency NEET targets.
Frequently Asked Questions
What is the general electronic configuration of transition metals?ā¾
The general electronic configuration for transition metals is `(n-1)dĀ¹ā»Ā¹ā° nsĀ¹ā»Ā²`. Here, `n` represents the principal quantum number of the outermost shell, and `(n-1)` is the principal quantum number of the penultimate shell containing the d-orbitals.
Why do chromium and copper show anomalous electronic configurations?ā¾
Chromium (Cr) and Copper (Cu) exhibit anomalous configurations due to the extra stability associated with half-filled (dāµ) and fully-filled (dĀ¹ā°) d-orbitals, respectively. This stability outweighs the energy cost of promoting an electron from the ns orbital to the (n-1)d orbital.
How are electrons removed from transition metals to form ions?ā¾
When transition metals form ions, electrons are always removed first from the outermost `ns` orbital, regardless of whether the `ns` orbital was filled before the `(n-1)d` orbital. After the `ns` electrons are removed, electrons are then removed from the `(n-1)d` orbitals if further ionization is required.
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