Question

Why does hydrogen naturally form diatomic molecules (H2), whereas helium exists as a single atom (He)?

Answer 1

Answer:

Hydrogen is a very reactive element. It doesn't exist as a single atom in nature. Neither do any of the other binary nonmetals -- nitrogen, oxygen, fluorine, chlorine, bromine, and iodine. They're too prone to react with something. They react with each other and form binary molecules because the binary molecules are more stable than single atoms (by a lot!). Compounds with other atoms are even more stable, so hydrogen reacts with oxygen to form water, and chlorine reacts with sodium to form table salt.

Explanation: