What is the electron configuration for aluminum?

##”Al: ” 1s^2 2s^2 2p^6 3s^2 3p^1##

For starters, grab a periodic table and look for aluminium, ##”Al”##. You’ll find it listed in period 3, group 13. Notice that the element has an equal to ##13##.

This tells you that a neutral aluminium atom contains ##13## protons inside its nucleus and ##13## electrons surrounding its nucleus. You can thus say that the for aluminium must account for a total of ##13## electrons.

As you know, electron configurations are written in accordance with the Aufbau Principle. The available empty orbitals in order of increasing energy look like this

Your goal now will be to start adding electrons to these orbitals. The first energy level contains a single orbital, so the first two electrons go in the ##1s## orbital

##”Al: ” color(blue)(1s^2)##

You’re now down to ##11## electrons. The second energy level contains a total of ##4## orbitals. The first orbital to be filled on this energy level is the ##2s## orbital

##”Al: ” color(blue)(1s^2) color(red)(2s^2)##

You’re down to ##9## electrons. The next ##6## electrons are distributed in the ##2p## orbitals

##”Al: ” color(blue)(1s^2) color(red)(2s^2 2p^6)##

You’re down to ##3## electrons. The first orbital to be filled on the third energy level is the ##3s## orbital

##”Al: ” color(blue)(1s^2) color(red)(2s^2 2p^6) color(green)(3s^2)##

Finally, the last electron is added to one of the ##3p## orbitals

##color(green)(|bar(ul(color(white)(a/a)color(black)(“Al: ” 1s^2 2s^2 2p^6 3s^2 3p^1)color(white)(a/a)|)))##

And there you have it, the complete electron configuration for aluminium.