Re: CCL:size of s,p,d orbitals

[John Bushnell <bushnell at.at chem.ucsb.edu>]

 Regarding the argument about "the lack of repulsion between
 the 2p orbital and a lower shell p-orbital", I would think
 that this would not be an issue.  If there was such a thing
 as a "1p" orbital, it would be spherically symmetric when
 filled.  Thus I wouldn't expect any inherently p-specific
 repulsion to such a filled subshell, if it existed.  That
 is, the s orbital would also experience such a "lack of
 repulsion" :-)
         - John          bushnell at.at chem.ucsb.edu
 On Thu, 4 Oct 2001, Ulrike Salzner wrote:
 > Dear Collegues,
 > until 1 hour ago, I firmly believed that p-orbitals are larger than s-
 > orbitals for atoms that are in the same row of the periodic table. Only
 > for the second row the sizes were about same. This conviction is mainly
 > due to a paper by Werner Kutzelnigg, Angew. Chem. 1984, 96, 262-286. I
 > further believed that s electrons are attracted stronger by the nuclei
 > because they have no node at the position of the nucleus and that the
 > similar size of s- and p-orbitals in the second row is due to the lack of
 > 1p orbitals and therefore cancellation of two effects: less attraction of
 > p electrons due to the node and lack of repulsion between 2p and a lower
 > shell p-orbital. This is also what I kept telling our first year students.
 >
 > Today a collegue approached me who teaches inorganic chemistry to our
 > third year students. She told me that she was surprized that the students
 > did not know that the order according to decreasing size is s > p > d
 > within the same row. After admitting that this was to be blamed on me, she
 > showed me the Inorganic Chemistry textbook by Huhee. There are plots of
 > radial distribution times r square, clearly indicating that the maximum
 > shifts to smaller values from s to p to d. Huhee quotes Herberg's
 "Atomic
 > Spectra and Atomic Structure" from 1944. In Kutzelniggs article the
 > average distance of electrons from the nucleus was used not radial
 > distribution times r square.
 >
 > The question now is: Do the two ways to determine the size of the orbitals
 > lead to different conclusions? Is there a mistake somewhere? Is there
 > newer information? Which orbitals are bigger? What is best method to
 > determine the size to explain bonding, hybridization, or lack thereof and
 > so on?
 >
 > Thanks in advance for suggestions,
 > Ulrike Salzner
 > ===================================================================
 >
 > Dr. Ulrike Salzner
 > Associate Professor
 > Department of Chemistry		Tel.: (312) 290-2122
 > Bilkent University		Fax.: (312) 266-5097
 > 06533 Bilkent, Ankara 		e-mail: salzner at.at fen.bilkent.edu.tr
 > Turkey
 >
 > ====================================================================
 >
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