Is it FONClBrISCH or FOClNBrISCH?

[arc5005]

FONClBrISCH or FOClNBrISCH

Saw a post from 2009 saying "FONClBrISCH" was incorrect from the TBR books. Kinda confused now for remembering the electronegativity of these common elements.

Or are the electronegativity values for Cl and N just too similar, and so it doesn't really matter?

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[NextStepTutor_1]

Hi @arc5005 ,

Excellent question! The shortest answer to your question would be that it doesn't really matter for the MCAT. Electronegativity trends are way more important than specific values, especially for atoms that show very similar behavior.

However, just from the point of view of scientific thoroughness, the reason for this discrepancy is that multiple methods have been developed for calculating electronegativity. The basic trends of electronegativity are the same regardless, but the details vary based on the method. The electronegativity values you're most likely to see are known as the Pauling values (according to which Cl has an electronegativity of 3.16 and N has an electronegativity of 3.04). The Allen scale, however, has different values -- 2.87 for Cl and 3.07 for N. It looks like the top chart you included uses the Allen scale, although the value for Cl is slightly different than what I found in other sources.

That said, don't worry about it too much -- the specific differences among various electronegativity scales go beyond the scope of the MCAT.

Hope this helps, & best of luck as you study!

 

[arc5005]

Thank you.

 

[NextStepTutor_1]

You're very welcome!