D-And F-Block Elements Ques 417
Question: Electronic configuration of $ Cu(Z=29) $ is
[Pb. CET 2001]
Options:
A) $ [Ar]3d^{9}4s^{2} $
B) $ [Ar]3d^{10}4s^{1} $
C) $ [Ar]3d^{5}4s^{2} $
D) $ [Ar]3d^{6}4s^{2} $
Show Answer
Answer:
Correct Answer: B
Solution:
The expected electronic configuration of Cu (29) is $ [Ar]\ 3d^{9}4s^{2} $ but actually it is found to be $ [Ar]\ 3d^{10}4s^{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.
