Question

Generalize the rules for writing electronic configuration of the first eighteen elements found in the modern periodic table.

Answer 1

We have to know that the distribution of electrons in the atomic orbital can be expressed in terms of electronic configuration. For example, the electronic configuration of sodium is $1{s^2}2{s^2}2{p^6}3{s^1}$ . The electronic configuration can be used to find out valency of an element. And it is used to determine the properties of the element present in a group. If the elements have the same electronic configuration, it exhibits the same properties. And the electronic configuration can be written by using the subshell labels.

Complete answer:
Let’s discuss about that there are some rules for writing electronic configuration of the first eighteen elements found in the modern periodic table and that is,
If n represents the energy level or number of orbit, then 2n is equal to the maximum number of electrons present in the given energy level. The number of electrons present in the K shell is equal to two, the L shell contains a maximum of eight electrons, and the maximum number of $18$ electrons.
The outermost orbits should not contain eight electrons.
The electrons should be filled in a stepwise manner in the different orbital. Which means, the electrons will not accommodate in a higher orbit or shell without completing the given orbit.

Note:
As we know, according to quantum chemistry, the arrangement of electrons of an atom in atomic orbital or arrangement of electrons of molecules in molecular orbital is known as electronic configuration. For writing the electronic configuration, it should be started from the shell number and the symbol is ‘n’. And the electronic configuration may help to determine the properties of an element.