[dontwanttofail]

For example, methane is a gas at room temp while pentane is a liquid.  Does it have to do with polarizablitiy of electrons at all?  because this came up in a section talking about polarizability

Thanks   

[UG]

The polarity of the molecules is certainly a factor, gases have weak intermolecular forces, solids have strong ones.

[dontwanttofail]

but how would that determine what phase it is in?

My prof said that the gas phase favors neutural molecules.  I don't exactly understand this.  So are you saying that less polar molecules that are less likely to have intermolecular interactions are more likely to be in the gas phase whereas polar molecules that are interacting are more likely to be in the liquid because they are more stable there?

[UG]

So are you saying that less polar molecules that are less likely to have intermolecular interactions are more likely to be in the gas phase whereas polar molecules that are interacting are more likely to be in the liquid because they are more stable there?

Yes! That is exactly what I'm saying (okay maybe not exactly but close enough) 

Less polar molecules aren't less likely to have intermolecular forces, they just have weaker ones, i.e. temporary/instantaneous dipole induced-dipole attractions, these dispersion forces are very weak, so the molecules are further apart from one another, making it more likely to be gaseous. Polar molecules have stronger intermolecular interactions,i.e. permanent dipole-dipole attractions, they are more likely to be a liquid or a solid because these attractions keeps the particles closer together so that less escapes, resulting in a liquid or a solid. 

[dontwanttofail]

OH maaan... thanks so much.

I am taking a computational chemistry course.  I've taken through Org I and II and Biochem but had such baaad gen chem courses that its plauged me for years, didn't know anything about gen chem... not sure how I passed org I.  Now I took this course so I would force myself to learn gen chem properly, something I thought I could never do.. I really feel I am starting to get the hang of it.  This question really made me think and my prof is reluctant to help.... you really helped me a lot out here in thinking the right way.  I'm so grateful!