From chemistry-request #at# ccl.net Mon Jun 2 10:07:08 2003 Received: from soul.helsinki.fi (soul.helsinki.fi [128.214.3.1]) by server.ccl.net (8.12.8/8.12.8) with ESMTP id h52E76gC031240 for ; Mon, 2 Jun 2003 10:07:07 -0400 Received: from localhost (mpjohans-: at :-localhost) by soul.helsinki.fi (8.9.3p2/8.9.3) with ESMTP id RAA349313 for ; Mon, 2 Jun 2003 17:07:06 +0300 (EEST) X-Authentication-Warning: soul.helsinki.fi: mpjohans owned process doing -bs Date: Mon, 2 Jun 2003 17:07:06 +0300 (EEST) From: Mikael Johansson X-X-Sender: mpjohans(at)soul.helsinki.fi To: chemistry(at)ccl.net Subject: CCL: Summary: History of atomic shell labels Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=ISO-8859-1 Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from QUOTED-PRINTABLE to 8bit by server.ccl.net id h52E78gC031241 Hello All! The recent discussion on orbitals reminded me that I never posted a summary on a few questions I posed two years ago. As it's some time ago, and I didn't get an answer for everything, here comes the questions again. The summary part is further below: 1.) Who came up with the idea of starting labeling of the atomic shells from K, L, M..., and more interestingly; why start from K? 2.) The subshell labels came from the spectral lines of alkali metals, but where Sharp, Principal and Diffuse lines are quite self explanatory, I have some difficulty of picturing a "Fundamental" spectral line :-) Any help? 3.) Was there a good reason for leaving out j from the labels for subshells? So far I've managed to get a definitive answer on the origin of K, L, M, etc., which was introduced by Barkla, 'K' coming from German "K|rzere Wellenldngen" and 'L' from "Ldngere Wellenldngen". This was suggested by Eric Scerri (see below) and I also found it in a book by V. Trkal, Electronic Structure of Atoms and Molecules (1969). j was apparently left out just to avoid confusion. No definitive answer on that though. No-one has had any idea of the origin of the "fundamental" spectral line. Below is a list of the replies I've got. The book by Trkal was recommended to me by Dr. Henrik Konschin of our lab. Have a nice day, Mikael J. http://www.helsinki.fi/~mpjohans/ ===================================== From: Steve Williams [...] >3.) Was there a good reason for leaving out j from the labels for > subshells? The story I have heard about this is that since j and J are used both as general angular momentum quantum number symbols, as well as for total (spin + orbital) angular momentum, it was thought too likely to cause confusion if j and J were used as orbital angular momentum symbols as well. Good luck with your search... Steve Williams ASU Chemistry Boone, NC 28608 USA ======================================== From: Eric Scerri [...] (1) The historical origin of K, L, M etc dates back to the work of the British X-ray spectroscopist George Barkla who was later awarded a Nobel Prize. If I recall his key article was in 1911 in the Philosophical Magazine. He is mentioned in all standard historical accounts such as the books by Pais for example. Title: Inner Bound. It was his work which led to van den Broek's suggestion that the ordering principle for the periodic system might be atomic number rather than atomic weight which in turn inspired Moseley to experimentally verify this idea in 1914. van den Broek also cited Geiger and Marsden's famous experiements on the scattering of alpha radiation. More about all these episodes appears in my forthcoming book on the Story of the Periodic System to be published by McGraw-Hill as a 'trade book'. (2) no idea! (3) Presumably because j or even J is used for the vectorial sum of l and s and L and S respectively. Having an orbital labeled j would just confuse matters. regards, -- Dr. Eric Scerri , UCLA, Department of Chemistry & Biochemistry, 607 Charles E. Young Drive East, Los Angeles, CA 90095-1569 USA ======================================== From: Michael Nolan Hi, I can answer number 1 for you: K = kurz L = lang and after that it's alphabetical. kurz is german for short lang is german for long. The early spectroscopists were german! regards Mick [...] -- ******************************************************** Michael Nolan Computational Modelling, NMRC Lee Maltings, Prospect Row, Cork, IRELAND ======================================== From: Huub van Dam [...] > 3.) Was there a good reason for leaving out j from the labels for > subshells? I would think it was thought that j could be mistaken for being an i too easily. However, I have authorative information on this one. [...] -- ======================================================================== Huub van Dam E-mail: CCLRC Daresbury Laboratory phone: +44-1925-603362 Daresbury, Warrington fax: +44-1925-603634 Cheshire, UK WA4 4AD ========================================================================