The collection

Every essay — page 40

Page 40 of 40, continuing through the fields in the same order.

Orbitals Where the atoms go Bonding models What symmetry decides Beyond the octet What a spectrum settles When the molecule does not stop What the shape is for What is taught wrongly Series Named objects Orbitals Refutations Search

What is taught wrongly

The explanations that are confident, memorable and false — stated fairly and then tested against a calculation rather than an opinion.

$The repulsion each bond needs, and the one Born and Mayer's law supplies. For each bond, the fraction of the ion pair's attraction a repulsion must reach before moving a whole electron stops paying (open circle), and the fraction a Born–Mayer repulsion of range 0.345 Å supplies at the measured length if the ion pair is to sit at its own minimum there, ρ/R (filled). Three bonds need none because they never transferred. Hydrogen fluoride needs 0.351 and is supplied 0.376; hydrogen chloride needs 0.116 and is supplied 0.271; the alkali halides need three quarters and are supplied a fifth or less. Every verdict comes out right — hydrogen fluoride's by a margin of 0.025.$

A repulsion the proton does not have

Asked whether moving one whole electron pays, eight bonds with measured dipoles came out six right and two wrong: hydrogen fluoride and hydrogen chloride, both predicted ionic. The proposed fix was the repulsion between the two ions' closed shells. Add it the way an ion pair demands of itself, and the score becomes eight of eight — but the repulsion that does it is largest for the shortest bonds, and the shortest bonds are the ones whose cation is a bare proton with no shell at all. The term a proton really has, penetration into the anion's cloud, undoes hydrogen chloride and not hydrogen fluoride. And the measured bond energies demand a repulsion only for the three alkali halides.

6 figures