Final answer:
The alkali metal in period 2 is lithium (Li) with an atomic number of 3, and its electron configuration is 1s² 2s¹.
Step-by-step explanation:
The alkali metal in period 2 of the periodic table is lithium (Li), with an atomic number of 3. The electron configuration of lithium can be determined by adding electrons one at a time to the lowest energy orbitals available in sequence, which for lithium is up to the 2s orbital. The first two electrons fill the 1s orbital, giving us 1s² for helium, and the remaining electron goes into the 2s orbital. Therefore, the full electron configuration of a neutral lithium atom is 1s² 2s¹.