[shehri]

Hi all,

     In text books it's said that CH4 has lowest B.P in its group because it's a very small molecul as compared with SnH4 etc.& has least polarizability.Plz. explain the reasons of its low B.P.Thanks.

[Yggdrasil]

How would the polarizability of the molecule affect London dispersion forces (i.e. induced dipole-induced dipole interactions)?  Are these types of interactions stronger for molecules with greater polarizability?

[shehri]

yes indeed,Lomdon Dispersion forces're stronger for heavy molecules because elements of higher atomic numbers have their outer most electrons loosely bonded & so electronic cloud distortion which cuses london forces increases.So resultantly their polarizability increases too.CH4 has less size than SnH4 because Carbon at the top of IV-A group has atomic number 6 while Sn has 50.Other reason is symmetric structure of CH4 which hinders polarization too..