How to write the electronic configuration of any element

The electronic configuration of an element is written in the following format: 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6 7s2. This is the universal order in which electrons fill up different orbitals. However, each element has a unique electronic configuration depending on the number of electrons it has.

To write the electronic configuration of an element, you need to follow the Aufbau principle which states that electrons fill up orbitals starting from the lowest energy level and moving to higher energy levels. The order in which the electrons fill up different orbitals is determined by the Pauli exclusion principle and Hund’s rule.

The Pauli exclusion principle states that each electron in an atom must have a unique set of quantum numbers. Two electrons cannot occupy the same orbital unless they have opposite spin. Hund’s rule states that when electrons fill up orbitals with the same energy level, they tend to occupy individual orbitals with the same spin before pairing up.

Let us consider the electronic configuration of carbon which has an atomic number of 6. The atomic number of an element is the number of protons in its nucleus. Carbon has six electrons which are distributed in different energy levels or shells. To write the electronic configuration of carbon, we need to follow the Aufbau principle and fill up the orbitals starting from the lowest energy level.

The first two electrons of carbon occupy the 1s orbital. Therefore, the first part of the electronic configuration of carbon is 1s2. The next two electrons occupy the 2s orbital which is at a slightly higher energy level. Therefore, the electronic configuration of carbon becomes 1s2 2s2. The remaining two electrons occupy the 2p orbital. However, since the 2p orbital has three suborbitals, we need to apply Hund’s rule which states that they need to occupy individual orbitals with the same spin first before pairing up. Therefore, the electronic configuration of carbon becomes 1s2 2s2 2p2.

Another example is the electronic configuration of oxygen which has an atomic number of 8. Oxygen has eight electrons which are distributed in different energy levels or shells. Again, we need to follow the Aufbau principle and fill up the orbitals starting from the lowest energy level. The first two electrons of oxygen occupy the 1s orbital. Therefore, the first part of the electronic configuration of oxygen is 1s2. The next two electrons occupy the 2s orbital which is at a slightly higher energy level. Therefore, the electronic configuration of oxygen becomes 1s2 2s2. The remaining four electrons occupy the 2p orbital. Applying Hund’s rule, we find that three of these electrons occupy individual orbitals with the same spin first before pairing up. Therefore, the electronic configuration of oxygen becomes 1s2 2s2 2p4.

In conclusion, writing the electronic configuration of any element requires an understanding of the Aufbau principle, Pauli exclusion principle, and Hund’s rule. By following these principles, one can predict the electronic configuration of any element and understand its chemical properties. The electronic configuration is an essential concept in chemistry and forms the basis of many chemical calculations and predictions.