I am taking AP Chemistry, and have noticed that I can identify a polyatomic polar molecule, but struggle to determine which molecule is the most polar given a set of several polar molecules.

What would be a basic procedure/set of questions to ask myself in determining which molecule is the most polar? I hope my question is not too general...

Thank you!


closed as too broad by airhuff, jerepierre, Todd Minehardt, paracetamol, M.A.R. Apr 24 '17 at 10:59

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  • $\begingroup$ Difference in electronegativity values between the two atoms sharing the bond should give some idea about the bond's polarity. $\endgroup$ – Pritt says Reinstate Monica Apr 24 '17 at 4:19
  1. Determine which molecules are polar out of the given options.
  2. Determine the polar bond (This will be the bond causing the molecule to be asymmetrical)
  3. The molecule with the polar bond that has the greatest difference in electronegativity is the most polar. For example a carbon-oxygen bond is more polar than an oxygen-fluorine bond because the difference in electronegativity for oxygen and carbon is greater than the difference between fluorine and oxygen.

You can find electronegativity values in the following table or a table like it, I am not sure if you are provided with one. If not you can normally judge electronegativity by the how fare an atom is from fluorine, as seen in the table below. The size of the molecule also affects polarity, for example polarity decreases with the size of alcohols, but large complex molecules should not come out at your level.

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