AUGUST, 19.54
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A SOPHOMORE COURSE IN INORGANIC CHEMISTRY JOHN A. WILKINSON Iowa State College, Ames, Iowa
DUE to the expansion of physical, organic, colldal,
3. I t may have eliminated some inorganic, where it had been used to illustrate some lam or generaland nutritional chemistry in the freshman textbooks, ization. inoreanic is being more and more curtailed in the freshman year. Thi'makes it desirable and almost a necesHowever, it does give some idea of the amount of genera1 sity to have a sophomore, or advanced, course in inormaterial in the freshman tests. ganic chemistry to teach the fundamentals of the suhI t is not right to assume that having had a year's ject. The inorganic that the usual freshman knows is work in general chemistry a student is well prepared in limited to the first two short series in the periodic table. inorganic, any more than to assume that he is prepared Anything below that is, to him, mostly a closed book. in organic or physical. This is not intended as a criticism of either the textThe enormous amount of descriptive material in book, the teacher, or the student. It is merely a stategeneral chemistry is not inorganic. For example, the ment of the fact. We must realize that the first-year only chemistry in making sulfuric acid is the oxidation chemistry as taught everywhere is general chemistry of sulfur or iron sulfide in air to sulfur dioxide, and the and not inorganic. The first course is taught, not for further oxidation of this, by air, using a catalyst, t o freshman chemists nor chemical engineers but for the sulfur trioxide, and finally the hydration of the oxide. general student who may be majoring anywhere, and A discussion of the mechanism of the lead chamber this will be perhaps the last chemistry he will ever take. process or the contact process is not inorganic chemistry For such a course, and for such students, the texts are any more than is it organic chemistry to give a comadmirable, to give a broad view of the whole field of plete discussion of the operation of a still because it is chemistry, but they are not inorganic chemistry. used in making alcohol. An examination of eight of the newer editions of presWhat is needed is a course studying inorganic in the ent-day popular texts in general chemistry shows that same manner used to study organic. If an organic stuthe amount of non-inorganic material presented varied dent is asked about the reactions of acetyl chloride, he is from 36 to 62 per cent, with a mean of about 45 per able to give them, because herecognizes it asatypecomcent. I n some ways this check may not be entirely pound which he has studied, whose reactions he knows. accurate because: If a student is asked for the reactions of sulfuryl or 1. It does not eliminate the descriptive material thionyl chloride, he is stumped. He does not realize that this also is a type compound, all members of which used in describing inorganic material. 2. The chapters on hydrogen, oxygen and water act alike. The organic instructor teaches his material were called all inorganic, although they were on the basis of type compounds and type reactions. Even a home economics sophomore girl on seeing a mostly physical.
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JOURNAL OF CHEMICAL EDUCATION
444
COOH group in an organic compound, recognizes it as an acid, and that the compound will have some acid reactions. There are three problems that are involved in presenting such a course in inorganic chemistry: 1. The time available. 2. The choice of a textbook. 3. The method of teaching. Iowa State College is a technical school and not a university, and has an outlined curriculum in chemical technology. In this the Department of Chemistry is permitted to give about what it pleases and is not bound by a general curriculum committee, as might be the case if the school were a university. In spite of the difficulty of adding more required chemistry courses to an already overloaded chemistry curriculum, in which the A. C. S. committee has stipulated a minimum of 60 quarter credits in chemistry out of a possible 192 credits to graduate, there has been introduced in the sophomore year a two-credit course for two quarters, or about 48 class periods. Originally this was closely correlated with the course in quantitative analysis and was taught by the same instructor. Although now taught by a different instructor the two courses are still closely related. I t is somewhat difficult to find a text that gives the material desired and a t the same time does not contain too much other material that is not wanted. Almost any of the intermediate texts will serve by a proper elimination. Mellor's Intermediate text was used first, but lately Foster's "Inorganic Chemistry for Colleges" has been substituted. This book has some 900 pages, and is of course too large. However, the first 90 pages cover the usual preliminary discussion about matter, energy, elements, molecules, gas laws, eta., and this may be omitted. There are 76 pages given to organic chemistry and foods, 115 pages on molecular weights and elementarv" whvsical chemistrv. * " - . which for our w r Dose may also be omitted. This still leaves 600 pages covering so-called inorganic, including descriptive material. Even this is too much for 48 class periods, We give to the student a set of study sheets, 56 pages of mimeoera~hednotes. These cover what we consider essential for him to learn. When the course was first started some 30 years ago,
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Mellor's text was used, going through it as i t was written. The good students were plainly bored by the repetition of the elementary material such as the gas laws, energy, molecular weights, etc., which they had had not only in general chemistry, but also back in the high-school chemistry and physics. Also at the end of the course the students had gained very little in inorganic because of the mass of descriptive material introdnced.
We next tried to lecture the material. This also was not too successful as the sophomore students were slightly too immature t o take notes complete enough t o get what was wanted. The present method is somewhat of a tutor system. The class sections are limited to 30 students. Assignments are made in the study sheets and in the text, and in class questions are asked about this material. Often the answers are not given directly in the text, but may always be deduced from this assignment, together with generalizations that have been previously made, or from some rule or law the student has had before. The idea is to get the student to think in terms of his previous knowledge, to use what he knows, and to guess what he does not know. As far as possible generalizations are used, and exceptions noted if there are any. Students usually like the method of generalizing and are more or less familiar with it from their qualitative analysis. There they made such generalizations, as to the solubility of chlorides, sulfates, nitrates, etc. They are also familiar with such generalizations as Le Chatelier's theorem, law of Dulong and Petit, Faraday's law, Graham's law, etc., which they can use. After a brief development of the periodic table and atomic structure, a page in the mimeographed notes gives a series of rules regarding basicity, acidity, and stability of the oxides in the different groups, and in the A and B families in the groups. Similar rules are given for the pseudo-hydrides in Groups IV, V, VI, and VII. . Further generalizations are made as t o (a) Occusrence and preparation of the elements of differenttypes. (b) P:eparation of kids, bases and salts. (c) E n d of compounds and salts formed by different types of .>--A-L-
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As the families are studied the application of these generalizations are made and the variations in the family itself shown and accounted for.
