Question

Valencies of the elements isdetermined by the number of electrons present in the outermost shell ,so why the valency of argon is 0 not 8?

Answer 1

Valency of an atom is defined as the combining capacity of the atom. The valency of an atom is determined by number of electrons present in the valence shell of the atom. It is equal to the number of electrons lost, gained or shared by an atom in order to achieve the nearest noble gas configuration. Argon itself is an inert gas which contains 8 electrons in its valence shell. Hence it does not need to lose, gain or share the electrons present in the valence shell. Thus its valency is zero.