Oxygen exists as a diatomic molecule in nature when it is not combined with any other element. It forms O2 molecule because it is stable when it is uncombined. It has the lowest energy level when uncombined. ... By achieving octet configuration, the diatomic elements become more stable compared to the single atom.
Aluminum, boron, and gallium are likely together in one group because they have the same number of valence electrons, and carbon and germanium are likely together in another group because they have the same number of valence electrons.
