2
$\begingroup$

I've been told by my teacher that van der Waals forces is the formal name for intermolecular forces. But on the internet, many people are saying van der Waals forces is another name for London dispersion forces. If van der Waals forces is another name for dispersion forces, why is it named after another scientist?

$\endgroup$
1
  • 1
    $\begingroup$ I think these terms are often loosely defined. For example in general chemistry, van der Waals would also include dipole-dipole, dipole induced dipole etc. interactions (which are not dispersion), but wouldn't include hydrogen bonds. However, in molecular dynamics, the van der Waals parameters also contain information about hydrogen bonds, but it does not include dipole-dipole etc. forces. $\endgroup$
    – S R Maiti
    Mar 27 at 23:28
4
$\begingroup$

van der Waals forces is not another name for London dispersion forces. In his answer, airhuff has given IUPAC definition for van der Waals forces.

London dispersion forces are the intermolecular forces that occur between atoms and between nonpolar molecules as a result of the motion of electrons in those atoms and molecules. They are induced dipole-induced dipole interaction, better described in following diagram:

London dispersion forces

These inter-atomic or inter-molecular forces are the weakest of van der Waals intermolecular forces. London dispersion forces got its name due to its discoverer, Fritz London (Ref.1). You can find some details of the distance dependence on London forces here.

References:

  1. Fritz London, "The general theory of molecular forces," Trans. Faraday Soc. 1937, 33, 8b-26 (https://doi.org/10.1039/TF937330008B).
$\endgroup$

Not the answer you're looking for? Browse other questions tagged or ask your own question.