Question

Give a reason why-- Helium is considered monoatomic , but hydrogen a diatomic molecule​

Answer 1

Answer:

Helium is considered monoatomic and hydrogen is considered diatomic. A molecule is said to be monoatomic if they cannot form molecules by combining with other atoms because their outer shell is complete with no free valence electrons. ... Hydrogen is diatomic because it has to valence electrons in its outer shell.

Answer 2

bcoz it has ns1 electron configuration like alkali metal as it form h+ cation