They spread outward in every direction to regions where they are in low concentration. Your nose is able to detect the smell of the cologne or perfume even if you are quite a distance from the bottle that has been opened. Diffusion occurs in all states of matter: solid, liquid, and gas.
enclave, exclave - An enclave is a group or area different from the surroundings, a secured area within another secured area, from Latin clavis, key; an exclave is the same thing, but usually describes a portion of a country separated from the main part and surrounded by politically alien territory.
enclave. n. 1. (Government, Politics & Diplomacy) a part of a country entirely surrounded by foreign territory: viewed from the position of the surrounding territories.