Rules of Electron Distribution

The electron of a hydrogen atom in its ground state is located in the nearest orbital to the nucleus. But, what about the electron distribution of the atoms with more than one electron Answering this question in 1925, Wolfgang Pauli stated his exclusion principle thus  

According to this principle, the quantum numbers, n, 1, mp and ms, can never be identical for two electrons in an atom. This means that at least one of the quantum numbers must be different. For example, even if two electrons have identical values for n, 1 and m, (as a result of being in the same orbital), their magnetic spin quantum numbers must be different. That is, these electrons are said to have opposing spins. In fact, we have already mentioned that each electron may be described by a set of the four quantum numbers  

The Aufbau principle basically states that the lowest energy orbitals are filled first. Is orbital has the lowest energy, so it is first to be filled, followed, in order, by 2s, 2p, 3s... This ordering was first stated by Wolfgang Pauli and is called the Aufbau principle (aufbau means building up in German). 

In some cases, at higher quantum levels, since the energies of some subshells are very close to each other, there may not be any coherence between the order 

an Austrian physicist, is best known for his exclusion principle regarding the distribution of electrons among the atomic orbitals, for which he was awarded the 1945 Nobel Physics Prize. In his exclusion principle, Pauli says that no two electrons in the same atom may have identical sets of all four quantum numbers..  

---

Two general rules of electron distribution are based on the periodic law ... 

---