Question

The electronic configuration of potassium is 2, 8, 8, 1 and not 2, 8, 9.

Answer 1

Hint: In order to deal with this question first we will elaborate the octet rule further we will take an example of potassium to prove the question statement is true.

Complete step-by-step answer:

Octet law: The octet rule states that atoms are most stable when eight electrons occupy their valence shells. It is based on the fact that the atoms of the main group elements appear to be involved in chemical bonding in such a way that each atom of the resulting molecule has eight electrons in the shell of valence. The law of the octet applies only to the principal group elements.
The halogens, oxygen, nitrogen, and carbon molecules are believed to follow the laws of the octet. The elements that follow this law usually include the s-block elements and the p-block elements (except hydrogen, helium, and lithium).
Therefore, according to the law of the octet, an atom's outermost shell can accommodate up to 8 electrons (with the exception of a K shell that can accommodate up to 2 electrons). Hence, the electronic configuration of potassium is 2,8,8,1 and not 2, 8, 9.

Note- The outermost shell of any element is the shell of Valence. Atoms in individual elements have various electrical properties, based on the atomic number of each element. The electrical arrangement refers to the distribution of electrons in various shells / orbits / levels of energy at each atom.
The number of electrons in the outermost shell of a given atom determines either its reactivity, or a propensity to form chemical bonds with other atoms. This outermost shell is known as the valence shell, and the electrons trapped inside are known as valence electrons.