What is the strongest intermolecular force of attraction?

1 Answer
Apr 21, 2018

Quite probably #"hydrogen bonding..."#


We speak of #"intermolecular forces of attraction"#, and so immediately we can dismiss ALL non-molecular substances, i.e. ionic solids, network covalent solids, metals etc. And now let us consider the humble water molecule, and ammonia, and hydrogen fluoride...and compare its volatility with the heavier hydrides of Group 15, 16, and 17.


The boiling points of water, ammonia, and hydrogen fluoride, dwarf those of methane, and dwarf those of the heavier hydrides of the elements of Group 15, Group 16, and Group 17. And, CLEARLY, we may attribute this to the phenomenon of hydrogen-bonding, where hydrogen is bound to a strongly electronegative element, such as nitrogen, OR fluorine, OR oxygen. And the involatility of the water molecule, in which hydrogen bonding is MOST effective, is a clear consequence of this.

And so I maintain that the strongest intermolecular force of attraction is #"intermolecular hydrogen bonding"#. The volatility of water, a mere #18*g*mol^-1# with respect to mass, but which is a whopping normal boiling points of #100# #""^@C#, is clear and persuasive evidence of this proposition.