Mendeleev's Periodic Table- Cover Sheet SCI Home | SCI Faculty Page | Case Notes | Reference List | Users Notes

Author - Tom Huber – Summer 1998

Case Purpose This case requires students to discern patterns in a group of observations concerning some of the chemical elements known to Mendeleev, and to use the resulting ordered knowledge to make a specific prediction. Observations must be organized using two criteria (atomic mass and chemical properties) into a grid that reproduces part of Mendeleev’s periodic table. Because one chemical element is "missing," students should be able to predict its atomic mass and its chemical properties.

Relation to Texts Students are provided a set of cards that provide information about 18 of the elements known to Mendeleev. This information includes for each element (1) the name, (2) the symbol, (3) the relative atomic mass, (4) one or two physical properties, (5) the reactivity of the element, and (6) various ways the element combines with oxygen and hydrogen to form molecules. This information represents "primary scientific information" (Ziman, ISS, 2.2), which is descriptive. The students must notice that some of the chemical or physical properties of the elements allow one to categorize the elements into more "general" groups (Ziman, ISS, 2.3). By using increasing relative atomic mass as one criterion, and common chemical or physical properties as a second criterion, the students can discern a particular "pattern of facts" (Ziman, ISS, 2.4). Because one element is "missing," students should be able to make a "prediction" (Ziman, ISS, 3.6) as to its existence, its atomic mass and its chemical or physical properties.

Description of Case Materials Two set of cards constitute the case materials: one set of element cards for building the Mendeleev table and a second set of cards of organic molecules. The cards need to be printed, cut, and organized alphabetically for issuance to the student groups.

Case Use Student groups are given the set of cards and asked to organize them in the most meaningful way possible (i.e., one which allows them to discern a pattern and make a specific prediction). Of course, any periodic table in the classroom should be removed, and they must not use their chemistry books! While trying to organize the cards, groups should be asked by the roving professor what criteria they are using. After about 30 minutes of work, each group explains to the class their method of organization. A consensus (Ziman, ISS, p. 10) of the grid is determined, and each group writes a specific prediction. The prediction is the existence of an element between calcium and titanium in RAM, and with similar chemical and physical properties as boron and aluminum. Mendeleev predicted this element (scandium) in just this manner. If a second set of cards is desired (for homework or instead of the elements) they are available in another word document. Their use is explained in Case Notes.

Reference List Any introductory chemistry book will provide ample background or one could consult Chapter 7 in Trefil, J. and R. M. Hazen. 1998. The Sciences; An Integrated Approach. John Wiley & Sons, New York, New York. ISBN 0-471-16117-9.