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

From: "Robert E. Harris" <[email-masked]>
Date: Thu, 4 Oct 2001 13:39:13 -0500

The discussion given in Chs. 8 and 9 of Slater's Quantum Theory of Atomic
Structure, v. I still seems to me one of the clearest on the subject.

John C. Slater, Quantum Theory of Atomic Structure, v. I, McGraw Hill, New
York, Toronto, London, 1960.

REH

>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: [email-masked]
>Turkey
>
Robert E. Harris  Phone: 573-882-3274.  Fax:  573-882-2754
Department of Chemistry, University of Missouri-Columbia
Columbia, Missouri, USA 65211