Question

The electronic configuration of $Cu$ is

• A. $[Ne]3s^23p^63d^94s^2$
• B. $[Ne]3s^23p^63d^{10}4s^1$
• C. $[Ne]3s^23p^63d^34s^24p^6$
• D. $[Ne]3s^23p^63d^54s^24p^4$

Answer 1

Answer: (B)

Atomic number of $Cu$ is $29$ .
Thus, its electronic configuration can be written as
$Cu _{29}=1 s^{2}, 2 s^{2}, 2 p^{6}, 3 s^{2}, 3 p^{6}, 3 d^{10}, 4 s^{1}$
(Since, fully filled orbitals are more stable, so one electron from $4 s$ orbital transfers into $3 d$ orbital.)
The electronic configuration of neon is
$Ne _{10}=1 s^{2}, 2 s^{2}, 2 p^{6}$
Thus, using inert gas, the configuration of Cu can also be represented as
$Cu _{2 \theta}=[ Ne ] 3 s^{2}, 3 p^{8}, 3 d^{10}, 4 s^{1}$