STD 12 - 4. d and f- block elements — JEE STD 11 Science — Question
Gujarat BoardEnglish MediumSTD 11 ScienceJEESTD 12 - 4. d and f- block elements4 Marks
MCQ
Electronic configuration of $Cu(Z = 29)$ is
A
$[Ar]3{d^9}4{s^2}$
✓
$[Ar]3{d^{10}}4{s^1}$
C
$[Ar]3{d^5}4{s^2}$
D
$[Ar]3{d^6}4{s^2}$
✓
Answer
Correct option: B.
$[Ar]3{d^{10}}4{s^1}$
b (b)The expected electronic configuration of $ Cu (29)$ is $[Ar]\;3{d^9}4{s^2}$ but actually it is found to be $[Ar]\;3{d^{10}}4{s^1}$. This is because fully filled $d$ orbitals are more stable than incompletely filled $d-$ orbitals. So there is a migration of one ${e^ - }$, from $4s $ orbital to $3d$ orbital to give a more stable configuration.
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