Question

which is the electron configuration for lithium? 1s² 2s³ 1s²2s¹ 1s¹2s²

Explanation:

Step1: Determine the atomic number of lithium

The atomic number of lithium (\(Li\)) is \(3\). This means a neutral lithium atom has \(3\) electrons.

Step2: Apply the Aufbau principle

According to the Aufbau principle, electrons fill the lowest - energy orbitals first. The \(1s\) orbital has lower energy than the \(2s\) orbital. The \(1s\) orbital can hold a maximum of \(2\) electrons. After filling the \(1s\) orbital (\(1s^{2}\)), the remaining \(1\) electron goes into the \(2s\) orbital (\(2s^{1}\)).

Answer:

\(1s^{2}2s^{1}\) (the third option)