Answer:
There is an interaction called intermolecular forces.
Step-by-step explanation:
Intermolecular forces are the forces exerted to hold together two or more molecules. They correspond to chemical bonds that have the function of binding or repelling the molecules of a compound.
In the case described in the question, the intermolecure forces would act by imposing a force of attraction between the molecules that would make those particles that move freely if they "stick" to the clumped particles.