Question

Electronic configuration of copper is?
A. \[[Ar]4{{s}^{2}}3{{d}^{9}}\]
B. \[[Ar]4{{s}^{1}}3{{d}^{10}}\]
C. \[[Ar]4{{s}^{1}}3{{d}^{8}}\]
D. \[[Ar]4{{s}^{2}}3{{d}^{7}}\]

Answer 1

Hint: Attempt this question by writing the atomic number of Copper. Then, arrange the elements in such a way so as to put them in the state of maximum stability. Keep in mind – half filled orbitals are very stable.

Complete step by step answer:
Copper is a d block element Group 11 (I b) of the periodic table with atomic number = 29. The electronic configuration of copper should be \[[Ar]3{{d}^{9}}4{{s}^{2}}\], but instead it is \[[Ar]3{{d}^{10}}4{{s}^{1}}\]. This is due to the fact that a completely filled (containing one electron per orbital) orbital has a greater stability.
The greater stability is due to the following factors –
Symmetrical distribution of electrons –
As we know, symmetry leads to stability. Therefore, electronic configurations of half-filled and completely filled orbitals are more stable.
In case of copper, \[3{{d}^{10}}\]is completely filled and is more stable compared to \[3{{d}^{9}}\].
Exchange energy –
Half-filled and completely filled electronic configurations are also stable due to the large exchange of energy of stabilization. Exchange means shifting of electrons from one orbital to another in the same subshell.
Therefore, the answer is option (b) – the electronic configuration of copper is \[[Ar]3{{d}^{10}}4{{s}^{1}}\].

Note: Chromium, atomic number – 24 also shows an exceptional configuration like copper. Its configuration should be \[\text{ }\!\![\!\!\text{ Ar }\!\!]\!\!\text{ 3}{{\text{d}}^{4}}\text{4}{{\text{s}}^{2}}\]. But due to stability on the basis of symmetrical distribution of electrons and stability due to exchange energy. \[\text{ }\!\![\!\!\text{ Ar }\!\!]\!\!\text{ 3}{{\text{d}}^{\text{5}}}\text{4}{{\text{s}}^{\text{1}}}\].