Which of the following electron configurations represents the transition element Chromium \(_{24}Cr\)?
\(1s^{2} 2s^{2} 2p^{6} 3s^{2} 3p^{6} 4s^{2} 3d^{4}\)
\(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}3d^{6}\)
\(1s^{2}2s^{2}2p^{6}3s^{2}3d^{4} 4s^{1}\)
\(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{1}3d^{5}\)
Explanation
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Discussions (11)
Since the last electron enters the 3d-subshell, the expected electronic configuration of Chromium (Cr)(Z=24) is
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d⁴
But the observed electronic configuration is
1s² 2s² 2p⁶ 3s² 3p⁶ 4s¹ 3d⁵
The reason for this:-
We know that half filled & fully filled orbitals are stable. We also know that d-orbital can have maximum of 10 electrons. In Chromium, it is only one electron less than achieving the stable half filled electronic configuration & it also has somewhat similar energy as 4s orbital. So, it borrows ine electron from 4s-orbital & becomes half filled & stable.
answer is D ooo... half filled orbitals tend to show stability hence they are most preferred
They selected a wrong answer for the electron configuration of Chromium. The correct answer is meant to be (D) and not (A)
