Polarity based on number of lone pairs

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Frenz Cabison 1B
Posts: 54
Joined: Fri Sep 29, 2017 7:07 am

Polarity based on number of lone pairs

Postby Frenz Cabison 1B » Sun Nov 26, 2017 6:33 pm

Why is a molecule polar when the central atom has one lone pair of electrons? Can we determine the polarity of a molecule just by looking at the number of lone pairs?

Gurshaan Nagra 2F
Posts: 49
Joined: Thu Jul 27, 2017 3:01 am

Re: Polarity based on number of lone pairs

Postby Gurshaan Nagra 2F » Sun Nov 26, 2017 6:51 pm

Lone pairs force the molecule to not be symmetric and thus polar

Ozhen Atoyan 1F
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Re: Polarity based on number of lone pairs

Postby Ozhen Atoyan 1F » Sun Nov 26, 2017 7:00 pm

When the central atom has a lone pair the molecule will be polar. In general if we look at the dipoles of two atoms, they may cancel, however, if a lone pair is present then the atoms will not have the same equal and opposite dipoles. Therefore, the lone pair will interfere and the dipoles will change, which will not allow it to cancel. Thus, it will be polar. To determine polarity we should still look at the the bonded atoms. Technically, if there is a lone pair then the molecule will be polar, so yes maybe that is a shortcut?


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