We’ve all seen and use the so-called Aufbau Diagram. It is a mnemonic used to remember the order of “filling” of atomic orbitals during the construction of the ground state electron configurations of the elements. The presentation of this diagram is largely disconnected from any physical meaning. Here’s what we tell our students: “Memorize the diagram, learn to use it, and you’re guaranteed to get the right answer.”
A complete understanding of why each element has a particular electronic configurations is a very complex subject. Even so, some confusion regarding the electronic configurations of the elements may be alleviated by looking at the physical properties of the electronic orbitals.