Helium has two electrons in its only energy shell while Argon and Neon have 8 electrons in their valence shells. As these have maximum number of electrons in their valence shells they do not have any tendency to combine with other elements. Hence they have a valency equal to zero.
Answers & Comments
Verified answer
Answer:
because they are noble gases
Explanation:
they fill the k l m n shell properly
Answer:
hope you like it
Explanation:
Helium has two electrons in its only energy shell while Argon and Neon have 8 electrons in their valence shells. As these have maximum number of electrons in their valence shells they do not have any tendency to combine with other elements. Hence they have a valency equal to zero.