explique this:  I read in "Solomons", book organics chemistry that   WHEN there arent hidrogenio bounds(ponte de hidrogenio), the forces of van der walls are more important than atractions dipole dipole, so the book  show the example of NH3 that the energy of dipole dipole is 3.3  Kcal. mol-1 and the van der walss is 3,5 Kcal. mol-1 , other example is HBr that dipoloe dipole is 0,006 kcal.mol-1 and de van der walls is 6,7 Kcal. mol-1

AND i learn with my professor that dipole dipole is more  effective and more strong than van der walls, and i read  in teory books it too, Brady,Masterton, Kotz, Peter Atkinz.....  SO WHY  THIS??

AND which POLARITY or POLARIZABILITY then influence more in prediction about TEemperatura of ebulition??

because the both are opposite  increases in  tabela periodic, polarity increases with eletronegative and polarizability increases with the  raio atomic(volume)(small ou big). ANSWER THIS  please!

van der Waals forces of attraction may originate from dipole-dipole and dipole-induced dipole interactions as follows :

i) Dipole- dipole interactions : In case of polar molecules, the van der Waals' forces are mainly due to electrical interaction between oppositely charged ends of the molecules called dipole-dipole interactions. For example, gases such as NH3, SO2, HCl, HF, etc. have permanant dipole moments as a result of which there is appreciable dipole-dipole interactions between the molecules of these gases. The magnitude of this type of interaction depends upon dipole moment of the molecules concerned. Evidently greater the dipole moment, stronger is the dipole-dipole interactions. Because of these attractive forces, these gases can be easily liquified.

ii) Dipole induced-dipole interactions : A polar molecule may sometimes polarize a non-polar molecule which lies in its vicinity and thus induce polarity in a that molecule just as a magnet induces magnetic polarity in a neutral piece of iron lying close by.The induced dipole then interacts with the dipole moment of the first molecule and thereby the two molecules are attracted together. The magnitude of this interaction, evidently depends upon the magnitude of the dipole moment of the polar molecule and the polarizability of the non-polar molecule. The solubility of inert gases in H2O increases from He to Rn due to a corresponding increase in magnitude of the dipole induced dipole interaction as the polarizability of the noble gas increases in size from He to Rn.