editorially /peaking An Arbitrary Aspect of Science Have you ever wanted t o express your opinion on an imDortant issue in chemistrv? You mav"verv.well have that ooportunity soon. One aspect of science involves the confrontation of the unknown-in the physical world; another is the search for Datterns of understanding derived from ex~erimentalresults. understanding often comes from attempts t o organize facts, data, observations, etc., by processes that are invariably the product of human intellect. Frequently understanding derives from organizational schemes that incorporate rather arbitrary components. For example, introduction of the mole concept which focuses attention on the number of combining entities that undergo reaction rather than on their masses, makes chemical stoichiometry comprehensible and much more useful than ordinary recipes. Chemistry developed in an environment where it was much easier to weieh reactine substances than to count the number of reacting species, and, indeed, the concept of a species wns derived from an attrmDt ro organize mass relationshins. The organizational concepi of themole allows chemists to determine the number of a particular molecular species from the mass of a sample; weighing a sample is a rather simple experimental task cornoared to counting the number of molecules p r e w ~ in t that ~r?mple.~lln~s, insight as well as simpliriry ii introdured into a bewildering array of numhers rhst represent rracting masses when ideas are expressed in terms of moles. Mnssei of reacting suhstances usually make little sense to the uninitiated whereas the same basic information expressed in terms of moles leads to substantial simplification. Thus the fact that 1.37 e of barium react comoletelv with 2.52 g of iodine does not convey as much understanding does the counteroart statement that 0.01 moles of barium react completely kith 0.01 moles of iodine. Arbitrariness in chemistrv. is e~itomized in the nomencla. ture oithe elements. Hirtorirally, the disroverer of an element claimed the right to name it. This practice has led to an array of names commemorating places, people, and things. he dispute in recent years over the right to name element 104 has soawned the sugeestiou that all of the elements should he ;amed on the h& of their atomic numbers which, of course, 59.123 (1982)l. Since elements are unioue [THIS JOURNAL. combine to-form compounds, it was iogicii to establish the identity of a compound from its constituent elements using combinations of symbols for the constituent elements. Although these symbols are arbitrary, they have come to rep-
resent a variety of ideas: a mole of the element: a sinale atom of the element; and all of the properties associated-with an atom of the element, such as its relative or absolute mass. Such symbols can be elaborated to impart more information. Thus, the symbol Na+ implies that a stable compound containing this species, which is derived from the element sodium in a specific way, must also contain a species of the opposite charge. Perhaps it is the special way in which chemists try to provide insieht into the nature of chemical nrocesses hv anolvine "controlred arbitrariness" that causes drohlems for students. For examole. . . it doesn't matter what vou name an element. if you are considering the position it occupies in the periodic chart, but the name becomes very important if you want t o search the literature. I t is not often that practicing chemists-both teachers and researchers-have an opportunitv to express an opinion on a subject which may aff& our fuiure pe;ception oirhe periodic chart. They du have that opportunity today. As Fcrnelius and Puwell desrribe in this issue innee .. 6'741.,, the modern o c riodic chart evolved without much guidance or apparent need for meement concemine the details of submouo oreanization. ~ ~ m oby s tdefault wk now have a situation where there is confusion reeardine the desienation of the A and B elements. The root of the con&xion is ciearly demonstrated by Fernelius and Powell. However. the best amroach to eliminatine" the .. confusion is less ob\,ious and more runtro\w.iiirl. The lnternational IJnion of Pure and Aoolied rhemistw tlL'PAC1 u,ill probably make a recommendai
