1s² 2s² 2p⁶ 3s² 3p¹

Here's how to understand it:

* 1s²: The first energy level (n=1) has one subshell (s) with 2 electrons.

* 2s²: The second energy level (n=2) has an 's' subshell with 2 electrons.

* 2p⁶: The second energy level also has a 'p' subshell, which can hold up to 6 electrons.

* 3s²: The third energy level (n=3) has an 's' subshell with 2 electrons.

* 3p¹: The third energy level also has a 'p' subshell, which has 1 electron in Aluminum.

Important Note: Aluminum has 13 electrons. The electron configuration follows the Aufbau principle, which dictates filling orbitals in order of increasing energy.