A standalone atom has direct part one 'nucleus' and one 'electron_cloud'. An O 'atom' within an O2 'molecule' is an 'e-bonded_atom'. In this material branch, H atom is a particular case, with respect to higher atomic number atoms, since as soon as it shares its electron it has no nucleus entangled electron cloud. We cannot say that H2 molecule has direct part two H atoms, but has direct part two H nucleus.
Atom