Question

For each of the following substances, state whether the intermolecular forces are primarily hydrogen bonding, permanent dipole, or temporary dipole.  

Sil_4  

HCN

Answer 1

A. In case of SiI4,

Electronegativity are Si = 1.8 and I = 2.5 . Bond is polar.

But as molecule is tetrahedral , net polarity cancel each other. Therefore it is temporary dipole. And hydrogen bonding is not possible as H is not present

B. In case of HCN , H is not directly bonded to N therefore no possibility of hydrogen bond.

Electronegativity differences show that it is a polar bond. And all polar bonds are permanent dipole. Therefore, HCN has permanent dipole as intramolecular force .