From chemistry-request@server.ccl.net Thu Oct 4 14:25:43 2001 Received: from umc-mail01.missouri.edu ([128.206.10.216]) by server.ccl.net (8.11.6/8.11.0) with ESMTP id f94IPhB31236 for ; Thu, 4 Oct 2001 14:25:43 -0400 Received: from [128.206.98.1] (mu-098001.dhcp.missouri.edu [128.206.98.1]) by umc-mail01.missouri.edu with SMTP (Microsoft Exchange Internet Mail Service Version 5.5.2653.13) id 4GNNJF72; Thu, 4 Oct 2001 13:25:43 -0500 Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" X-Sender: HarrisR@pop.email.missouri.edu Message-Id: In-Reply-To: Date: Thu, 4 Oct 2001 13:39:13 -0500 To: Ulrike Salzner , ccl From: "Robert E. Harris" Subject: Re: CCL:size of s,p,d orbitals 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: salzner@fen.bilkent.edu.tr >Turkey > Robert E. Harris Phone: 573-882-3274. Fax: 573-882-2754 Department of Chemistry, University of Missouri-Columbia Columbia, Missouri, USA 65211