Question

Why helium is considered monoatomic but hydrogen a diatomic molecule ?

Answer 1

Answer:

1. helium can exist independently symbol=H therefore monoatomic hydrogen cannot exist independently symbol=H2 therefore diatomic

Answer 2

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.
• Although helium has two electrons to share, it is stable and hence is considered as a noble gas and monoatomic.
• Hydrogen is diatomic because it has to valence electrons in its outer shell.