Potential Energy of London interactions

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Steven Garcia 1H
Posts: 79
Joined: Fri Sep 28, 2018 12:16 am

Potential Energy of London interactions

Postby Steven Garcia 1H » Wed Nov 07, 2018 11:46 pm

The equation for the potential energy of London interactions is -(alpha1*alpha2)/r^6. The concept that the potential energy increases with increasing polarizability of the molecules involved makes sense to me. However, for highly polarizable molecules, we would expect for them to have a larger radius since the outer electrons are farther from the nucleus and therefore more easily distorted. If this is case and the radius increases with polarizability, then wouldn't it make since for the potential energy of the London interaction to decrease (since the equation divides by the sixth power of the radius)?

Tarika Gujral 1K
Posts: 62
Joined: Fri Sep 28, 2018 12:27 am

Re: Potential Energy of London interactions

Postby Tarika Gujral 1K » Thu Nov 08, 2018 12:30 pm

In terms of bond strength: type of bond is more important than size of molecule

A larger radius, as you said, implies greater electron distortion
Greater distortion of electrons means that the atom is more easily polarizable: will more easily form a dipole
Since LDF forces are based on the formation of a dipole, an increased likelihood of dipole formation corresponds more to increased bond strength, rather than radius size.

George Ghaly 2L
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Joined: Fri Sep 28, 2018 12:29 am
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Re: Potential Energy of London interactions

Postby George Ghaly 2L » Thu Nov 08, 2018 5:00 pm

London Forces are the weakest forms of bonds created by instances moments of ionization, therefore bond length does not necessarily matter when discussing these bonds as their potential energy Is more influenced on the type of bond rather than distance.


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