Question

The electronic configuration of calcium ion $\left(Ca^{2 +}\right)$ is :-

• A. $1s^{2},2s^{2}2p^{6},3s^{2}3p^{6},4s^{2}$
• B. $1s^{2},2s^{2}2p^{6},3s^{2}3p^{6},4s^{0}$
• C. $1s^{2},2s^{2}2p^{6},3s^{2}3p^{6},3d^{2}$
• D. $1s^{2},2s^{2}2p^{6},3s^{2}3p^{6},3d^{5}$

Answer 1

Answer: (B)

Atomic number of calcium atom is $20$ so it has $20$ electrons
Electronic configuration of calcium atom is- $1s^{2},2s^{2}2p^{6},3s^{2}3p^{6},4s^{2}$
$Ca$ atom loses two electrons to form $Ca^{2 +}$ ion. These electrons are lost from outermost shell.
The electronic configuration of calcium ion $\left(Ca^{2 +}\right)$ is- $1s^{2},2s^{2}2p^{6},3s^{2}3p^{6},4s^{0}$