Question

An ion is an atom with an electric charge due to a loss or gain of an electron.
Which of the following is the electron configuration of a ground state of the most common alkali metal ion?

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

Answer 1

The correct option is B $1s^{2}2s^1$

Alkali metals are the group one $s$ block elements in which last electrons enter in nS energy level.

The general electronic configuration of $s-block$ elements is $n{s}^1$ where $n=2$ to $7.$