When you are studying the Aufbau principles, it is important to understand every single line of the principles. Aufbau comes from the German word “Aufbauen” which means “to build”. This means that when we are writing electron configurations, we are also building up electron orbitals as we proceed from atom to atom. These orbitals can be seen in these Aufbau diagrams below. The first one here is the electron configuration for carbon.
You can study the example of the Aufbau diagram above, as the electron configuration is written for an atom, the orbitals in order of increasing atomic number are filled. The Aufbau principle originates from Pauli’s exclusion principle which says that no two fermions in an atom can have the same set of quantum numbers, hence they have to “pile up” or “build up” into higher energy levels. How the electrons build up is a topic of electron configurations. The following diagrams below are the Aufbau examples of the chlorine and fluorine.
One of the rules of the Aufbau principle is that the orbitals are filled by one type of spin before the opposite spin starts to appear. In this case, the two spin-up electrons are placed in the first two empty slots, but the actual order is arbitrary. It could have been the second and third slot or the first and third. Below are the Aufbau examples of nitrogen and oxygen.
All of the diagrams provided above are examples of Aufbau principles. The diagrams are printable and can be downloaded in high quality. We also have other posts of educational diagrams that you can browse through our categories!