H2S and H2Se Relative Boiling Points

[Keerthana Sundar 1K]

Hello! This may be a dumb question, but I was wondering about this question from Matthew Nguyen's UA Worksheets?

Discuss the forces present in H2S and H2Se. Explain why H2Se has a higher boiling point than H2S.

So I initially thought, since S has a higher electronegativity than Se, H2S would have the higher boiling point. However, I feel like I'm missing something. Can someone explain to me why H2Se would have the higher boiling point? Thanks!

[Steph Du 1H]

When looking at what has a higher boiling point, we look at what has the strongest intermolecular forces. They both have dipole-dipole which I think are the same strength. I'm not sure if the higher electronegativity of S would make the dipole-dipole interaction stronger. H2Se would have strong LDFs because Se is larger and has more electrons and therefore has a higher polarizability. The strength of LDFs depends on polarizability.