I cannot for the life of me figure out how it works.
Edit: got it, thanks guys
In: 1
Most molecules have some sort of electric “dipole” – the electrons prefer to spend their time on one side of the molecule and so it has one negatively charged end and one positively charged end. This helps the molecules stick together in the liquid and solid phase.
But what about perfectly symmetric molecules like carbon dioxide?
We know it can still solidify when it gets cold enough, but it doesn’t have any sort of permanent dipole that would help this along. What’s holding the molecules together?
This is where the dispersion forces come in. The molecule has no *permanent* dipole but electrons are jumpy little things. At any given moment they may randomly shift to one end of the molecule or the other, creating a temporary negatively charged bias on that end.
This then encourages a reaction in the next molecule over, repelling those electrons and producing a positive. Repeat down the chain. The molecules slightly magnetize themselves by sheer randomness, and stick together in a chain reaction of self-reinforcing temporary dipoles.
It’s the weakest of the intermolecular forces, but in large volumes at low temperatures it still adds up. It’s what holds liquid oxygen and dry ice together.
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