The argon spontaneously disperses throughout the argon because dispersion of argon atom produces an increase in disorder.The disorder of element is measured by use of entropy.According to the second law of thermodynamic in a closed system tend to maximize entropy.
Answer is: the dispersion of argon atoms produces an increase in disorder. Argon and neon are gases, so they have high kinetic energy and move through space (gases move more disorderly. Entropy (amount of disorder) of system increases, the higher the entropy the greater is disorder.
