* 1s² 2s² 2p⁶ 3s¹
Explanation:
* 1s²: The first energy level (n=1) has one sublevel (s), which can hold up to 2 electrons.
* 2s²: The second energy level (n=2) also has an s sublevel that holds 2 electrons.
* 2p⁶: The second energy level also has a p sublevel, which can hold up to 6 electrons.
* 3s¹: The third energy level (n=3) starts with the s sublevel, which contains only 1 electron in the case of Sodium.
Key Point: The outermost electron (3s¹) is what determines Sodium's chemical properties and makes it highly reactive.
