Final answer:
The condition where net movement of molecules stops when they're evenly distributed throughout a space is called dynamic equilibrium.
Step-by-step explanation:
The condition where the net movement of molecules stops due to the containment of molecules being evenly spread is known as dynamic equilibrium. When a substance has diffused completely through a space, such that its concentration gradient is removed, molecules continue to move, but there is no longer a net movement of molecules from one area to another. Dynamic equilibrium is encountered in both living and nonliving systems, and it is essential for processes such as the diffusion of nutrients and gases within the body, as well as in the evaporation and condensation of liquids in a closed container.