[curiouscat]

Generally (very crudely) as molecular size increases it is less likely that a molecule is gaseous (say at Room Temp).

Got me thinking: what's the highest MW molecule that is still gaseous? Let's say, BP <20 C at 1 atm.

I can think of Radon (MW 222 ; BP -60 C) or SF6 (MW 146 ;  BP -64 C )

Alternatively, what's the molecule with the largest (number of constituent atoms) that is still a gas?

Wondering how high we can go? Especially interesting among hydrocarbons.

[fledarmus]

Going down the periodic table, SeF₆ and TeF₆ are both still gases, the later at MW ~ 242 and bp ~-40°C. Wikipedia shows that PoF₆ (MW 323) has been synthesized and was predicted to have a bp around -40°C, but I haven't seen the measurement.

[Borek]

WF₆?

[curiouscat]

WF₆?

That does seem the highest so far. Thanks!