Why are the tin(IV) halides more volatile than the tin(II) halides?

Tin(IV) halides have tin in +4 oxidation state while tin(II) halides have tin in +2 oxidation state. In tin(IV) halides, tin has formed 4 covalent bonds to the halogen atoms, whereas in tin(II) halides, tin has formed 2 covalent bonds to the halogen atoms.

Both tin(IV) halides and tin(II) halides are covalent in nature, with tetrahedral geometry for tin(IV) halides due to the 4 covalent bonds formed, and bent geometry for tin(II) halides due to the 2 covalent bonds formed. Tin(IV) halides are nonpolar, as the bond polarities cancel out in the tetrahedral geometry. On the other hand, tin(II) halides are polar due to the presence of lone pairs on the tin atom and the polar nature of the Sn-X bond (X being a halogen atom).

In general, the bond strength of tin(IV) halides is lower than that of tin(II) halides. This is because, in a tin(IV) halide, the tin atom is holding onto four electron pairs in the outermost shell, leading to an increased electron-electron repulsion and decreased bond strength. In a tin(II) halide, there are only two electron pairs in the outermost shell, resulting in less repulsion and stronger bond strength.

Volatility is the measure of the tendency for a substance to evaporate or turn into vapor. For a substance to evaporate, the intermolecular forces between the molecules need to be overcome. A higher volatility indicates weaker intermolecular forces, which can be easily overcome to turn the substance into vapor.

Tin(IV) halides are more volatile than tin(II) halides because of the differences in their polarity, bond strength, and structure. Tin(IV) halides are nonpolar, leading to weaker dispersion forces between the molecules, while tin(II) halides are polar and have stronger dipole-dipole interactions. Furthermore, tin(IV) halides have a weaker bond strength due to increased electron-electron repulsion in the tetrahedral structure. This makes it easier to break the bonds and turn the tin(IV) halides into vapor compared to tin(II) halides. In summary, the higher volatility of tin(IV) halides results from their weaker intermolecular forces (due to nonpolarity) and weaker bond strength, which enables them to more easily turn into vapor compared to tin(II) halides.