- In distinguishing between states of matter why do books refer to how closely particles are held together, rather than atoms or molecules?
Resources I have looked at distinguish between the three basic states of matter in terms of how closely particles are held together; i.e. in solids they are bound most closely, in liquids less so and in gases they're much freer. Would it not be more correct to refer to how closely atoms or molecules are held together rather than particles? Referring to particles suggests to me that particles are being exchanged between the atoms, is that the case? (If particles are not being exchanged then I would have thought the unit under consideration is the atom or molecule.)