I don't know if ALL gases exist as a diatom but several do. Hydrogen can exist as a single proton, or 1 in about 6420 in sea water will exist as a diatomic molecule called deuterium or (heavy water). read more
Hydrogen can exist as a single proton, or 1 in about 6420 in sea water will exist as a diatomic molecule called deuterium or (heavy water). Hydrogen can also exist as a proton and two neutrons, called tritium. read more