Finding negative pole of a molecule

[Lusin_Yengibaryan_3B]

How would we go about finding where the negative pole of a given molecule is? For example, how would we solve a problem given the lewis structures of the molecules?

Also, how do we figure out which molecule should have the higher dipole moment when given two lewis structures of molecules?

[Shanna Yu 1C]

Hi!

Without a specific example, I'm afraid I'm going to have to speak in more general terms, but I believe what you need to know is electronegativity.

We figure out which end of the molecule the negative pole is by asking ourselves which of the atoms/ends is more electronegative than the other, as the more electronegative end pulls harder on electrons.

It's the same reasoning with your second question. We'd look at the difference in electronegativities for the atoms in each molecule. Whichever molecule has the greater difference in electronegativity between its atoms is the one with a higher dipole moment.

Lemme know if you need clarification!

[Tanner Bartyczak 1K]

I agree with Shanna. There is probably another way to figure it out, but I always look at electronegativity, being how much an atom pulls on electrons. The atom with the higher electronegativity will most likely be the part of the molecule with the negative charge.

[Astha Patel 2J]

The best way would be to compare electronegativities and whichever atom has the greater electronegativity (electron pulling power) would be the negative end of the pole. The relative differences in electronegativity would also tell us which ones have a greater dipole moment (greater difference in electronegativity). Use the periodic table and the trend for electronegativity to qualitatively decide which end would be the negative pole.

[Andre Fabian 1F]

I agree with what everyone has stated beforehand.

Adding on, electronegativity tends to increasing going up a group or across (left to right) in a period. As such, we could infer that the more "negative" pole of a molecule tends to center around atoms found in the upper right corner of the periodic table. Furthermore, we can determine relative charges/attraction of each atom within a molecule by subtracting the electronegativity of one of the atoms in a bond with the other. \

Hope this helps!