Boiling point trend

[akimhaneul]

When comparing boiling point of h2o, h2s, h2se, and h2te, the trend is h2o>h2te>h2se>h2s. I understand that the greater molecular weight allows greater van der waals forces, but doesn't h2s have a greater dipole than h2te? H2o should definitely be first because of hydrogen bonding but I do not understand the trend for rest.



When you compare boiling points of molecules, does London dispersion usually beat dipole dipole forces unless it was hydrogen bonding?


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[aldol16]

If you look at electronegativity tables, the difference in electronegativity between H and S, Te, and Se is pretty small. So there isn't likely to be a huge dipole there anyway. So vdW contacts will likely be more important. But without knowing the electronegativity difference, it is difficult to tell.