Two oxygen atoms can form a double covalent bond with each other. This is because each oxygen atom has six valence electrons and needs two more to achieve a stable octet configuration.

Here's how it works:

* Each oxygen atom shares two electrons with the other oxygen atom. This forms a double bond.

* This double bond is represented by two lines in a chemical structure (O=O).

The resulting molecule, O2 (oxygen gas), is a very stable and common molecule in our atmosphere.