[sunshin3]

i m doing summerwork for ap chem but i never learn this before so  can anyone please explain this?

predict the formula of the solid ionic compound when each of the followig pairs are combines: Na and I

Also, how can you explain why propane is a gas, hexane is a liquid, and an dodecane, C12H26 is a solid at room temp.?

thanks

[yl88]

1) NaI
2) Dispersion force is the only force acting on those molecules. Larger molecules usually have stronger dispersion forces, thus a denser physical state.

[xiankai]

based on what u know about melting and boiling points, why would bigger molecules exist as low energy solids while smaller molecules exist as high energy gases?

[Donaldson Tan]

sunshin3: have you learned inter-molecular bonding?

[sdekivit]

thus a van der Waals force for example if you don't know what intermolecular bonding means

[sunshin3]

so i should figure out which intermolecular attraction they are, and then explain how different intermolecular forces effect the molecules?

[sunshin3]

actually i figured out that the second questions has something to do with polarizability so i get it now. thanks everyone!

[Donaldson Tan]

Also, how can you explain why propane is a gas, hexane is a liquid, and an dodecane, C12H26 is a solid at room temp.?

actually i figured out that the second questions has something to do with polarizability so i get it now. thanks everyone!

what polarizability? it is just that these 3 substances exhibit different degree of intermolecular bonding, with propane the weakest and dodecane the strongest. the strength of van der waals' forces is directly proportional to the size of the molecular electron cloud. whereby dodecane has the biggest number of electron.

in polarizability, you have to describe a 2 entities. the first entity that exhibits polarising power and the second entity that experiences the polarising power. the effect of the polarising power on the 2nd entity is term the polarizability.

[sunshin3]

i read about polarizbility so i thought maybe they r related. now i know it's worng, thanks geodome!