# High Viscosity of Noble Gases

Why are the viscosities of noble gases higher than almost all other gases? This seems counter-intuitive since they have much weaker inter-molecular interactions and lower boiling points.

Gas Viscosity Table: http://www.engineeringtoolbox.com/gases-absolute-dynamic-viscosity-d_1888.html

• I wonder if this is at all related to the unintuitive fact that gasses increase in viscosity as temperature is increased, unlike the majority of liquids. Noble gasses and higher temperatures both provide situations which behave closer to an ideal gas. – Nicolau Saker Neto Jan 9 '16 at 9:45
• It is very related. Higher gas temperature means higher particle velocity. Higher velocity means more collisions. More collisions means higher viscosity. – Agriculturist Jul 18 '16 at 20:49
• In the case of temperature particle velocity is increased by higher temperature as opposed to lighter particles (He, Ne, Ar.) – Agriculturist Jul 18 '16 at 20:55

Some noble gasses (He, Ne, Ar) are monatomic particles with a lighter mass than the diatomic elemental gasses. The light mass results in a much higher velocity particles at a given temperature (consider $E=\frac{3}{2}kT=\frac{1}{2}m \bar{v^2}$) resulting in more collisions. Xenon has a high molecular diameter, so the shear increase in size of the molecule increases the probability of a collision, thus reducing the mean distance it travels before a collision.