From chemistry-request@server.ccl.net Thu Oct 4 07:54:19 2001 Received: from century.fen.bilkent.edu.tr ([139.179.97.100]) by server.ccl.net (8.11.6/8.11.0) with ESMTP id f94BsGB22204 for ; Thu, 4 Oct 2001 07:54:17 -0400 Received: from pinar (pinar [139.179.97.99]) by century.fen.bilkent.edu.tr (8.9.1/8.9.1) with ESMTP id OAA09242 for ; Thu, 4 Oct 2001 14:51:59 +0300 (EET DST) Date: Thu, 4 Oct 2001 15:03:19 +0300 (EET DST) From: Ulrike Salzner X-Sender: salzner@pinar To: ccl Subject: size of s,p,d orbitals Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII 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@fen.bilkent.edu.tr Turkey ====================================================================