Why are London dispersion forces attractive?

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    Dispersion Forces
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Discussion Overview

The discussion revolves around the nature of London dispersion forces, specifically questioning why these forces are considered attractive rather than repulsive. The scope includes conceptual clarification and technical explanation related to intermolecular forces in chemistry.

Discussion Character

  • Conceptual clarification, Technical explanation, Debate/contested

Main Points Raised

  • One participant expresses confusion about whether London dispersion forces could be both attractive and repulsive, suggesting that this might lead to no net force.
  • Another participant asserts that London dispersion forces are always attractive, explaining that transient dipoles in one molecule induce dipoles in nearby molecules, resulting in attraction.
  • A further analogy is provided, comparing the interaction of dipoles to bar magnets, emphasizing that induced dipoles will always align to attract rather than repel.
  • A participant acknowledges the complexity of the topic and expresses a desire to improve their understanding.

Areas of Agreement / Disagreement

There is disagreement regarding the nature of London dispersion forces, with one participant questioning their exclusively attractive nature while another insists they are always attractive.

Contextual Notes

The discussion does not resolve the initial confusion about the nature of London dispersion forces, and assumptions about the definitions of attraction and repulsion are not fully explored.

fedaykin
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I've looked around in my basic chemistry books and haven't seen this directly answered, and I'm having trouble with it on the internet too.

Wouldn't said force be repulsive just as often as attractive and therefore have no net force?
 
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London forces are considered both attractive and repulsive fedaykin!
Hope that helps.
 
No Ed, London dispersion forces are always attractive. These are also known as induced dipole-induced dipole interactions. In one molecule, a transient dipole can be formed from there temporarily being more electrons on one side of the atom/molecule than the other. This transient dipole will then induce a dipole (uneven distribution of electrons) in a nearby atom/molecule. This induced dipole in the second molecule will always point in the same way as the dipole of the first molecule, resulting in an attractive interaction. A dipole will never induce a dipole that results in a repulsive interaction (as an analogy, putting a bar magnet next to another bar magnet will never cause the second magnet to align itself to repel itself from the first magnet).
 
Ah, thank you very much. I'm trying to become more diligent in my reading. That's hard for me, especially at 3:00 a.m.
 

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