Polar vs. NonPolar

(Polar molecules, Non-polar molecules, etc.)

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Emma Randolph 1J
Posts: 65
Joined: Fri Sep 28, 2018 12:29 am

Polar vs. NonPolar

Postby Emma Randolph 1J » Tue Nov 13, 2018 10:20 am

How can you tell if a molecule is nonpolar or polar by just looking at the periodic table rather than looking up electronegativity?

Fanny Lee 2K
Posts: 73
Joined: Fri Sep 28, 2018 12:29 am

Re: Polar vs. NonPolar

Postby Fanny Lee 2K » Tue Nov 13, 2018 10:44 am

Depending on where an element is on the periodic table, you can estimate how strong the electronegativity is. The larger the difference, the more polar since elements on the upper right is more electronegative than the upper left elements. Another ways is to see if the structure of the molecule is symmetrical. If it is symmetrical then it non-polar. If it is not, then it is polar.

Mayaal_Khan_4H
Posts: 41
Joined: Fri Sep 28, 2018 12:28 am

Re: Polar vs. NonPolar

Postby Mayaal_Khan_4H » Tue Nov 13, 2018 12:18 pm

Polarity depends on the electronegativity difference between two elements, if you go across the periodic table, the electronegativity increases and if you go towards the left of the periodic table, the electronegativity decreases, for example, the electronegativity difference of Cl2 would be 0 since the difference between the electronegativity of both Cl molecules cancel off, which makes it a non-polar molecule. On the other hand, HCl is a polar molecule because Cl is very electronegative whereas H has a low electronegativity which results in a bigger difference in electronegativity making HCl a polar molecule.

MaggieMatern_Dis1H
Posts: 30
Joined: Fri Sep 28, 2018 12:19 am

Re: Polar vs. NonPolar

Postby MaggieMatern_Dis1H » Tue Nov 13, 2018 1:23 pm

It is also important to note that molecular structure plays an important role in polarity. For example, C02 would be expected to be a polar molecule, since the difference in electronegativity of C and O is large. However, the two O's are on either side of the C, giving it a linear shape. Due to this shape, the partial negative charges cancel out, and the molecule is actually nonpolar.

dgerges 4H
Posts: 65
Joined: Fri Sep 28, 2018 12:24 am

Re: Polar vs. NonPolar

Postby dgerges 4H » Tue Nov 13, 2018 2:20 pm

MaggieMatern_Dis1H wrote:It is also important to note that molecular structure plays an important role in polarity. For example, C02 would be expected to be a polar molecule, since the difference in electronegativity of C and O is large. However, the two O's are on either side of the C, giving it a linear shape. Due to this shape, the partial negative charges cancel out, and the molecule is actually nonpolar.

and a good counterexample to this is h2o which has a bent shape and is polar!

daisyjimenezt
Posts: 30
Joined: Fri Sep 28, 2018 12:26 am

Re: Polar vs. NonPolar

Postby daisyjimenezt » Tue Nov 13, 2018 2:28 pm

If you only have a periodic table look for the electronegativities to be different enough but not too different that they are ionic. I believe that Prof. Lavelle said that the examples he will give us will be fairly obvious.


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