Polarisability and Size

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Ashley Kao 1H
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Joined: Thu Jul 25, 2019 12:16 am

Polarisability and Size

Postby Ashley Kao 1H » Sat Nov 09, 2019 11:35 pm

In lecture last week, we learned that stronger attractive interactions could be the result of increased size or molar mass, but why is this true? Wouldn't the bonds between the two molecules be longer if they were bigger which would indicate that the bonds are weaker?

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Joined: Sat Aug 24, 2019 12:17 am

Re: Polarisability and Size

Postby Goyama_2A » Sun Nov 10, 2019 2:21 am

I think I remember Lavelle explaining it as those larger molecule have more electrons, resulting in stronger London dispersion forces due to the fact that they have stronger instantaneous-induced dipoles.

Louise Lin 2B
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Joined: Sat Aug 17, 2019 12:15 am

Re: Polarisability and Size

Postby Louise Lin 2B » Sun Nov 10, 2019 12:32 pm

Polarizability increases as the volume of the atoms increase. This means that polarizability typically increases down a group and decreases left to right in a period. High polarizability makes molecules have larger dispersion forces that allow them to form temporary dipoles more easily. Bonds between molecules are formed by the temporary dipoles. This also means that molecules with high dispersion forces have higher boiling points as a property as well.

Sofia Barker 2C
Posts: 101
Joined: Wed Sep 18, 2019 12:21 am

Re: Polarisability and Size

Postby Sofia Barker 2C » Sun Nov 10, 2019 2:03 pm

I was confused by this concept too, but a classmate helped explain to me that when a molecule is larger, there are more electrons and thus more potential intermolecular forces to take place within the molecule. With more electrons, the intermolecular forces will be stronger and this influence distortions in other molecules. Hope this makes sense!

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