MadSci Network: Chemistry
Query:

Re: Why do the melting points of the transitional metals peak at 6B?

Date: Fri Oct 2 16:16:46 1998
Posted By: Dan Berger, Faculty Chemistry/Science, Bluffton College
Area of science: Chemistry
ID: 907005881.Ch
Message:

I am not an inorganic chemist, but the question is intriguing. My guess
would be that Group VIB (IUPAC Group 6) has six valence electrons -- but a
half-filled d subshell shell is especially stable.  This means that the
outer s subshell tends to have just one electron, possibly encouraging
metallic bonding to the point that the bond becomes much stronger and the
metals have rather higher melting points. From this argument one would
expect Group VIB metals to also be harder, and in fact my CRC handbook says
that chromium has a Moh's hardness of 9 (where diamond is 10); manganese
(Group VIIB, same row) has a hardness of 5. Unfortunately I was unable to
find hardnesses for other metals in the "neighborhood."

You may want to forward this to a solid-state physicist for comment.

Dan Berger




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