The Periodic Building of the Elements: Can a Periodic Table Be

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In the Classroom

The Periodic Building of the Elements: Can the Periodic Table Be Transformed into Stereo? Fu-cheng He and Xiang-yuan Li Department of Applied Chemistry, Chengdu University of Science and Technology, Chengdu, Sichuan 610065, The People’s Republic of China As we have shown, many molecular and crystalline models can be constructed by using a paper ribbon (1, 2). Interestingly, a periodic table of any size can be transformed into a stereo model, which we call the “Periodic Building of the Elements”. This model is useful and instructive in teaching general and inorganic chemistry. Moreover, it might attract the students’ attention to the periodic law of the elements, which is of fundamental importance in chemistry. To construct a periodic building of the elements, a submodel of the main group and the transition elements should be made in advance, and then a submodel of the lanthanides and the actinides is made in a simple procedure. The whole model is obtained by simply combining these two submodels together. In fact, by slightly changing the procedures described in the following paragraphs, the periodic building of the elements with other forms can be constructed. The reader is encouraged to try. Submodel of Main Group and Transition Elements The steps for making the submodel, including the main group elements and transition elements from a periodic table (with shortened version), are illustrated in Figures 1 and 2 and given below. 1. Cut a periodic table into two parts (excluding the lanthanides and actinides) along the vertical line at the right of Sc, Y, La, and Ac. 2. Use a paper ribbon about 3 units wide (the length of one side of a small square in the periodic table is taken as the unit length), to join the two cut parts of the periodic table together with glue, leaving the three squares vacant at the lower part (Fig. 1).

3. Draw lines as shown in Figure 1. Cut out the paper pattern along its outside edges, and make cuts along those lines with arrows at their terminal points. 4. Fold the cut pattern so that the dash lines in Figure 1 become concave folds and the dash-dot lines become convex folds. 5. Turn squares a and c to coincide and glue them together; then let square b (with some glue) cover the top. Notice that the rectangular d is perpendicular to squares a, b, and c. 6. Put some glue at the backs of the Sc and Zn squares and stick them to the two terminal parts of d. 7. Let f cover e and h cover g, and glue them together. Then stick j to h with k attached to the left edge of h. 8. Put some glue at the back of the Be square and stick it to h so that the right edge of l coincides with the left edge of m. 9. Let the squares labeled 1, 2, … ,7 at the left in Figure 1 coincide with the squares labeled 1, 2, … ,7 at the right in Figure 1, and glue them together. 10. Put some glue on the left parts of squares 1′, 2′, … , 9′ and glue them together in proper order so that the octagon at the top of the submodel is nearly covered (Fig. 2). As shown in Figure 2, the squares of the transition el-

Figure 2. The submodel including the main group elements and transition elements.

Figure 1. The pattern for the submodel including the main group elements and transition elements.

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Journal of Chemical Education • Vol. 74 No. 7 July 1997

In the Classroom

Figure 3. The pattern for the submodel including the lanthanides and actinides.

Figure 4. The submodel of the lanthanides and actinides.

ements form a box on which there is a reactangular gap 2 units high and one unit wide. This gap will be mended when another submodel including the lanthanides and actinides is connected to this one.

thanides and actinides (Fig. 4).

Submodel of the Lanthanides and Actinides The steps for making the submodel including the lanthanides and actinides are shown in Figures 3 and 4 and given below. 1. Draw lines around the squares of the lanthanides and actinides as shown in Figure 3. The lengths cb and pb′ are equal to 2 and 1/4 units, respectively, so as to make ∠ acb approximately 97°.

The Periodic Building of the Elements Put glue on the parts having oblique lines of the submodel of the lanthanides and actinides as shown in Figures 3 and 4, and insert these parts into the rectangular gap on the submodel of the main-group elements and transition elements (Fig. 2). Thus the two submodels are connected to yield the periodic building of the elements (Fig. 5), where the octagon at the highest top is covered with a piece of paper having the same dimension. It is fantastic that a real building having the form shown in Figure 5 can be seen on a university campus! Literature Cited 1. He, F.-c.; Liu, L.-b.; Li, X.-y. J. Chem. Educ. 1990, 67, 650. 2. He, F.-c.; Liu, L.-b.; Li, X.-y. J. Chem. Educ. 1994, 71, 734.

2. Cut out the paper pattern along its outside edges, and make cuts along those lines with arrows at their terminal points. 3. Fold the cut pattern so that the dash lines coincide with concave folds and the dash-dot lines coincide with convex folds. 4. Let the square above Ho cover the square above Er, and the square below Es cover the square below Fm. Glue each pair of squares together so that e 1e2 and e1 ′ e2′ coincide with e3e4 and e3 ′ e4′, respectively. 5. Let the rectangular part above Ce and Pr cover the rectangular part above Lu and Yb, and the rectangular part below Th and Pa cover the rectangular part below Lw and No, and glue each two rectangular parts together so as to cause f1f2 and f1′f2′ to coincide with f5f6 and, f5′f6′, respectively. 6. Fold the tetragons above Gd–Tb and Sm–Eu downwards and glue them together so that cb coincides with cd (see Fig. 3). 7. Finally, stick the reactangular part above Nd– Pm on the top of the submodel so f3f4 coincides with gd. Thus we obtain the submodel including the lan-

Figure 5. The periodic building of the elements.

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