To determine the electron configuration for lithium, we'll take into account that lithium has an atomic number of 3. This means lithium has 3 electrons.
The electron configuration follows a specific order based on increasing energy levels:
1. The first energy level (1s) can hold up to 2 electrons.
2. The second energy level starts with the 2s orbital, which can hold up to 2 electrons.
Following these rules, we can distribute the 3 electrons of lithium:
1. The 1s orbital can hold 2 electrons. So we start by filling this orbital: [tex]\( 1s^2 \)[/tex].
2. After the 1s orbital is filled, we move to the 2s orbital. We have 1 electron left to place in the 2s orbital: [tex]\( 2s^1 \)[/tex].
Combining these, the electron configuration for lithium is [tex]\( 1s^2 2s^1 \)[/tex].
Therefore, the correct option is:
[tex]\[ 1s^2 2s^1 \][/tex]
