when comparing melting point of halides(H-Cl and H-Br), why do we compare the number of electrons and talk about their Van der Waals forces instead of comparing the degree of overlap between the H and the X atom?

Question

anonymous · Answer

Van der Waals Forces depend on three factors:
1. Polarizabilty
2. Molecular Weight (Which will help you compare boiling points)
3. Molecular Shape (Which will help you compare melting points.)
----- Using Molecular Shape to compare melting points is a  good method because you visually see the difference. As branching increases, surface area decreases, which means the boiling point lowers.... But the more symmetry, the higher the melting point...

anonymous · Answer

why can't we use the bond energy method?

sriram · Answer

well thats bcoz in using that method there is not much difference between their bond energies>