Question

How many Valence Electrons are there in Argon?

Answer 1

Hint: Electrons which are present in the outermost shell of the atom are known as valence electrons and for the calculation of the number of valence shell electrons we should know about the electronic configuration of the atom.

Complete Solution :
Symbolically Argon is denoted as ‘$\text{Ar}$’ in the periodic table and its atomic number is 18.
-As we know that the atomic number $\left(\text{Z}\right)$ of an atom is always equal to the number of protons present inside the nucleus or number of electrons present in the orbitals outside the nucleus.
i.e. Atomic Number = No. of protons = No. of electrons
-So, the number of electrons in the Argon atom is 18 because it is present in the neutral state.
-Electronic configuration of Argon is shown as follow:
$1s^2,2s^{2}2p^6,3s^{2}3p^6$
Hence, from the above given configuration it is clear that the number of valence electrons in the Argon atom is eight.

Additional information-
Argon is present in the VIII A group of the periodic table and it is a noble gas, which means it is chemically very less reactive in nature due to stable configuration of outermost shell; that’s why it is always present in the monatomic form. Argon is present in the gaseous state, its appearance is colorless and it is an odorless gas. Argon is the most abundant gas in the environment after Nitrogen and Oxygen.

Note: Here some of you may do wrong calculation if you only count p-orbital electrons and leave s-orbital electrons. During the calculation of valence electrons always add electrons present in the s-orbital as well as in p-orbital of the outermost shell.