[thedoc (OP)]

Nina asked the Naked Scientists:

   

I was wondering which had a lower boiling point, liquid hydrogen or liquid helium?



I think I have read that helium has a lower boiling point, but could you explain why?



Thank you!



What do you think?

[djandersonza]

Helium has a lower boiling point because of weaker van de Waals Forces

[chiralSPO]

Helium has a lower boiling point because it is a single spherical atom. It has very little surface area, and is not very polarizable. Elemental hydrogen exists as a diatomic molecule (H2). Even though it has a lower mass than helium, H2 has the same number of electrons, and they are distributed over a larger space in the linear (not spherical) molecule. These electrons are more free to move within the molecule, which means it is polarizable. This difference in polarizability is responsible for the difference in strength of intermolecular forces.

[thedoc (OP)]

We discussed this question on our  show
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Click to visit the show page for the podcast in which this question is answered. Alternatively, [chapter podcast=1000582 track=13.12.24/Naked_Scientists_Show_13.12.24_1001784.mp3] listen to the answer now[/chapter] or [download as MP3]