Question

$Cr$ is member of $3d$ transition series of atomic number $24$. What will be its electronic configuration?

• A. $ [Ar]3{{d}^{6}}\,4{{s}^{2}} $
• B. $ [Ar]3{{d}^{5}}\,4{{s}^{2}} $
• C. $ [Ar]3{{d}^{4}}\,4{{s}^{2}} $
• D. $ [Ar]\,3{{d}^{5}}\,4{{s}^{1}} $

Answer 1

Answer: (D)

The correct electronic configuration of Cr is $ [Ar]\text{ }3{{d}^{5}},4{{s}^{1}} $ and not $ [Ar]\text{ }3{{d}^{4}},4{{s}^{2}} $ because exactly half filled and exactly full filled orbitals are more stable than nearly half filled and nearly full filled orbitals.