Question

select the most likely electron configuration for a stable positive ion for each of the elements below.

1. lithium

a $1s^1$

b $1s^2$

c $1s^2 2s^1$

d $1s^2 2s^2$

Explanation:

Step1: Recall Lithium's electron config

Lithium (Li) has atomic number 3, so its neutral electron configuration is $1s^2 2s^1$.

Step2: Analyze stable positive ion

A stable positive ion (Li⁺) loses its outermost (valence) electron. The valence electron is in the $2s$ orbital, so Li⁺ will have the electron configuration of $1s^2$ (since it loses the $2s^1$ electron).

Step3: Match with options

Option B is $1s^2$, which matches the electron configuration of Li⁺.

Answer:

B. $1s^2$