ELI5, why do some gases, like oxygen or hydrogen form a molecule with a pair of atoms, while others like helium are just single atoms flying around?

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ELI5, why do some gases, like oxygen or hydrogen form a molecule with a pair of atoms, while others like helium are just single atoms flying around?

In: Chemistry
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It has to do with the number of electrons available for bonding.

The first “orbital” can contain a maximum of two electrons.
The second “orbital” can contain a maximum of eight electrons.

Helium has two protons and two electrons, and is happy all by itself.

Hydrogen has one proton and one electron, so it bumps up against another hydrogen, and the two hydrogens share the two electrons, and they’re both fairly happy.

Oxygen has eight electrons total.
Two of them are happy in the first orbital.
Another four are fairly happy in the second orbital,
and the remaining two choose to tango with the loose two from another oxygen. Or with two hydrogens.

I can go into better depth, but this is ELI5