Question

Q. helium atom has 2 electrons in its valence shell but its valency is not 2. explain.

Answer 1

Valency is known as the capability of an element to form and react with other compounds.

Since , Helium had a complete octate and didn't react with any other elements .

That's y the valency of helium is not 2 .

Answer 2

because the octate of helium is complete and it is a stable element which does not reacts with other elements to form compound.as valency is the combining capacity;so helium has a complete octate it does not combine with other element to become stable as it is stable before because it's valance shell is completed so because of these reasons valency of helium and all the other noble gases there valency is 0