JOURNAL OF CHEMICAL EDUCATION
To the Editor: The teaching of systematic inorganic chemistry in our schools and universities has long suffered from the circnmstance that there is no standard form of the periodic classification of the elements. For purposes of descriptive inorganic chemistry it is common practice to employ the Mendeleev type of periodic table in which the groups are divided into A and B subgroups, hut a perusal of modern textbooks reveals several inconsistencies and in some cases considerable confusion in the grouping of the elements on this basis. In England, for example, we find that Sidgwick ["The Chemical Elements and Their Compounds," Oxford University Press 1950, p. xxviii] presents a periodic table in which nitrogen and phosphorus, oxygen and sulfur, and fluorine and chlorine are represented as A elements, although it is categorically stated in the text that "from Group IV onwards the first two elements of every group belong definitely more to the B than to the
A subgroups, whereas in Groups I, I1 and 111 they are more closely allied to the A elements." Apart from the representation of carbon and silicon as intermediate in character between A and B elements, this feature is correctly expressed in the classification adopted by Emeleus and Anderson ["Modern Aspects of Inorganic Chemistry," Routledge and Kegan Paul, London, 1952, P 21. The periodic table published by Paneth [Discouery, 9, 289 (1948)l diiers in several respkcts from that used by other authors, and all the elements of the short periods are treated as B elements with the exception of lithium, sodium, beryllium, and magnesium. It is true that these inconsistenciesmay be avoided by treating the members of the short periods as Typical Elements, but the difficulty remains with the elements of the long periods. The confusion arising from the different designation of subgroups is also evident in American publications. For example, Pauling ["General Chemistry," Freeman and Co., San Francisco, 1947, p.61 I represents the members of the transition series as A elements in accordance with the English custom, but in a recently published chart [The Laboratmy, 1951, 1001 they are designated B elements, and it is claimed in this connection that the data are "based on the results of a comprehensive survey of chemistry professors and instructors from many colleges and universities." The position a t present is far from satisfactory and can only lead to further bewilderment of the student.
AUGUST. 1953
It may well be that the real remedy lies in (a) replacing the A and B suhgronping by the more rational classification into Normal Elements (N), Transition Elements (T) and Rare Earth Type (R) in accordance with their electronic structures, and (b) introducing a special group for copper, silver, and gold, since these metals can function chemically as normal or transition elements [WEEELER,Chemistry & Industry, 42, 639 "Physicochemical Periodic Table," (1947); BOWDEN, Priory Press, Cardiff, 1947; DURANT, "General and
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Inorganic Chemistry," Longmans, Green and Co., London, 1952, p. 1171. It is surely time for the chemist to put his house or, a t least, his table in order, and steps should be taken, preferably by an International Committee, to standardize for pedagogical purposes what is, after all, "the most basic document of chemistry."
