Size and Electronegativity difference

[Diana_Diep2I]

When do we look at size and when do we look at electronegativity difference when it comes to checking to see which molecule has the higher boiling point? For example, H2S vs H2Se or SiH4 vs SiF4. Do I look at the electronegativity or the size/polarizability of the molecule?

[Jessica Castellanos]

For H2S vs H2Se, you should look at the size because the electronegativity of S and Se are really similar but size are very different. For SiH4 vs SiF4, you should look at electronegativity because the big difference in electronegativity of H and F. Hope this helps!

[Matt F]

From what I've been told you will usually be able to tell which one to compare. The molecules given will usually be similar in either electronegativity or size, so use that as a baseline and look at the one that's different

[Nick Lewis 4F]

Do you have any example questions of how this would be tested? I understand the concepts but dont see how it could be tested on a test