Tuesday, February 7, 2012

Conversations with Henry

Henry: "Isoelectronic" is a perfectly fine concept. No need for you to feel it's inadequate. I'll give you an even easier example. We can play the same game with carbon, nitrogen, and oxygen:

[Henry sketches the Lewis structures for N2 and CO]:
Henry:  Forget about the labels "C", "N", and "O" for a moment.  Don't let them color your thoughts. Think of them as the numbers 12, 14, and 16:

Me:  OK, but what does the little curved arrow 1p, 1n mean in your picture?

Henry:  That's your little Maxwell's Demon, moving a proton and a neutron from one side to the other. There's no net loss or gain, but rather just a transfer.

Me: Are you pushing electrons too?

Henry: No! The electrons haven't moved yet but they feel the polarization: suddenly there's an extra charge on the oxygen side and one less charge on the carbon side. The electrons rearrange, being drawn slightly closer to the oxygen, but not completely, and the carbon, having less positive nuclear charge, is polarized negatively by the electrons. The molecules electron's are polarized like this:
Me: Ah, that explains why carbon monoxide binds to metals like iron in hemoglobin via its carbon.

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