question_answer

The electronic configuration of chromium \[\text{(Z}\,\text{=}\,\text{24)}\]is:

A)  \[[Ar]4{{d}^{4}}4{{s}^{2}}\]                       

B)  \[[Ar]3{{d}^{5}}4{{s}^{1}}\]

C)  \[[Ar]3{{d}^{4}}3{{s}^{2}}\]                       

D)  \[[Ar]4{{d}^{5}}4{{s}^{1}}\]

Correct Answer: B

Solution :

                 Electronic configuration of chromium (atomic number = 24) is written as : To stabilize d-orbital one electron jumps from 4s to 3d. Now, the correct configuration is: \[=1{{s}^{2}},2{{s}^{2}}2{{p}^{6}},3{{s}^{2}}3{{p}^{6}}3{{d}^{5}},4{{s}^{1}}\]or    \[=[Ar]3{{d}^{5}},4{{s}^{1}}.\]