1s² 2s² 2p⁶ 3s² 3p¹

Here's a breakdown:

* 1s²: The first energy level (n=1) has 2 electrons in the s orbital.

* 2s²: The second energy level (n=2) has 2 electrons in the s orbital.

* 2p⁶: The second energy level also has 6 electrons in the p orbital.

* 3s²: The third energy level (n=3) has 2 electrons in the s orbital.

* 3p¹: The third energy level has 1 electron in the p orbital.

Important Note: Aluminum has 13 electrons, as indicated by its atomic number. This electron configuration follows the Aufbau principle, filling orbitals in order of increasing energy.