Van der Waals forces of hydrogen

wenxian

Why does the Van der Waals forces of hydrogen weakest in liquid state?

Borek

I doubt it is true that Van der Waals forces of hydrogen are weakest when the hydrogen is in a liquid state. But I also doubt this is the question you were asked, I suppose you were asked why the Van der Waals forces in liquid hydrogen are the weakest Van der Waals forces present in any substance.

wenxian

Thanks for correcting my mistake. That is what I was trying to ask. Can u explain the reason to me ?

Borek

What is the source of the Van der Waals forces?

wenxian

This force arises because electrons in molecules are moving at high speed in orbitals. At any instant in time it is possible for more electrons to lie to one side of the molecule than the other one. When this happens, Van der Waal's forces occur. The momentary imbalance of electrons provides the positive end of a dipole with the atomic nucleus providing the positive end of the dipole. Therefore, instantaneous dipole produces an induced dipole in the neighboring molecules. in my opinion,this is how Van der Waal's forces of attraction occur. Am I right? Please feel free to point out my mistake.

Borek

This is more or less correct.

Now, the answer to your original question lies in your explanation. If not for the electrons there would be no VdW forces, wouldn't it?

wenxian

Got it. Thanks!