# Are nucleons, atoms and molecules identical particles?

Why are nucleons, atoms and molecules considered identical particles (bosons or fermions) even if they can be distinguished by the state of their most elementary components?

Also, what size does a molecule have to be so we can we cease to consider two molecules of that specie identical?

• Buckyballs (C$_{60}$ molecules) have been shown to create an interference pattern. – Pieter Feb 13 '18 at 21:15
• @Pieter I think you need to explain why an interference pattern is significant in this context. – StephenG Feb 13 '18 at 21:18
• @undead, you are wrong. nucleons, atoms and molecules are not identical particles. Also, all molecules of one particular substance are identical. – niels nielsen Feb 13 '18 at 22:53
• OP referred to "molecules of that specie", and that is quite clear. – Pieter Feb 13 '18 at 23:41
• This explanation is pretty good: en.wikipedia.org/wiki/…. Notice that whereas in principle you can never distinguish identical particles, in some cases you can. See here: physics.stackexchange.com/questions/377078/…. Also related: physics.stackexchange.com/questions/283682/… – valerio Feb 14 '18 at 14:45