# Properties of superfluid Helium

h ttp://en.wikipedia.org/wiki/Superfluid

Wikipedia states that, in the context of superfluids:
Helium-4 atoms are bosons [whereas] helium-3 atoms are fermions.
I assume what is meant is that the atoms have bosonic an fermionic properties under super-cooled conditions.
I gather that the spin of the constituents of the atom (protons, neutrons, electrons) are added up to predict the properties.
My question is, why does the atom behave like one quantum mechanical entity, having it's own spin, when it is actually many parts?

I'm sorry for asking a sophomoric question.

Gokul43201
Staff Emeritus