![]() Then, the remaining five electrons occupy at 3p orbitals which have (n+ l) value of 4. In such cases, the orbital with a low ‘n’ value is filled first, and hence 3s orbital is filled after 2p orbital. 3s orbitals are filled after 2p orbital though both have the same (n+l) value of 3. Then electron will occupy at 2s orbital having (n+l) value of 2, and then to the 2p orbital which has 3 ( (n+l) value. ![]() According to this Principle, as well as Hund’s rule and Pauli exclusion principle, the first two-electron will occupy in 1s orbital as this orbital possesses the lowest (n+l) value of 1. Let us write the electronic configuration of Chlorine (Cl).Ĭhlorine has an atomic number of 17, which means that it possesses 17 electrons. This is the reason, 2 p orbital is filled first before 3 s orbital. Thus the factor 2 explained above operates and the orbital with the lowest ‘n’ value gets filled first. In the case of 2p and 3s orbitals, both have same (n+ l ) value i.e. After filling of 1s orbital, electrons will be consequently filled in 2s, 2p, 3s, and so on. The diagram given below explains the correct sequence of filling up of energy levels.Īs shown in the figure, electrons will be first filled in 1s orbital as it possesses the lowest (n+ l ) value. In the case where two orbitals have the same (n+l) value, the orbital with the lowest ‘n’ value will be filled first by electrons.Orbital having the lowest value of (n+l) is filled first.The correct sequence of filling of electrons in an orbital depends on two factors. in the pattern of their increasing energy. In other words, electrons are filled in the orbital in such a way that the orbital with the lowest energy gets filled first, then to the next higher energy level, and so on i.e. Aufbau Principle DefinitionĪccording to the Aufbau principle, “ electrons are filled in an orbital in the increasing order of orbital energy level“. The electrons are filled in an orbital following Pauli’s exclusion principle as well as Hund’s rule. Basically, this principle explains how electrons are distributed among energy levels in the ground states of atoms. This is the reason, it is also called a building-up principle or construction principle. ‘Aufbau’ is a german word that means construction or build up. ![]() Aufbau principle states that an electron occupies an orbital in the order of lowest to highest energy orbital.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |