An electrically neutral entity consisting of more than one atom (n > 1). Rigorously, a molecule, in which n > 1 must correspond to a depression on the potential energy surface that is deep enough to confine at least one vibrational state. This tag should be applied to question about certain molecules or a class of them.
From the IUPAC goldbook:
An electrically neutral entity consisting of more than one atom ($n > 1$). Rigorously, a molecule, in which $n > 1$ must correspond to a depression on the potential energy surface that is deep enough to confine at least one vibrational state.
It is, therefore, a necessary requirement to be a molecule, that the atoms are covalently bound to each other, i.e. covalent-compounds.
This tag should be applied to questions about certain molecules or classes of them. Other tags should also be applied to further narrow the field, for example organic-chemistry, inorganic-chemistry, physical-chemistry.
