No, there are plenty of molecules of elements. You can make molecules where all of the atoms are the same kind. O2 is a molecule. O3 is a molecule. H2 is a molecule. S6 and S8 are both molecules.
Thanks Chronos.
What if you have an antiproton and an antielectron ? Would that be hydrogen or anti-hydrogen? Could two anti-hydrogens form a molecule of anti H2 ?
Normal hydrogen is the one with “ordinary” protons and electrons. Anti-hydrogen is the stuff they manufacture at CERN. Due to symmetry you would expect to be able to get anti-dihydrogen, anti-water, etc.
If you could somehow make enough of them, antielements made of antiprotons, antineutrons (yes, that’s a thing), and antielectrons would behave (almost) just like the “normal” elements we’re familiar with.
The “almost” is because there are some extremely subtle differences, but even with particle accelerators and extremely carefully designed experiments, they amount to differences in the parts-per-thousand range. You’d have no hope of detecting them by mere ordinary chemical reactions.
But O2 is molecular oxygen and O is elemental oxygen. Extremely nasty and found in low earth orbit.