An Easily Constructed Bicapped Pentagonal Prism Model Shukichi Yamana Faculty of General Education, Kinki University, Kowakae, Higashi Osaka 577, Japan end IM) side of the envelope at N, 0, and P, . . and the rieht-hand " respectively. (3) The left lower part of the envelope is folded up at D so that the line DA falls on the line DP. (4) On the line DA, the point corresponding to the N is marked Q. (5) The left lower part of the envelope is unfolded. (6) A horizontal line, perpendicular to the left-hand side of the envelope at Q, is drawn so that it intersects the two lines (K) and (.M.)and therieht-hand sideof the envelope at R, S, and T, respectively
A model of a bicapped pentagonal prism, which is useful for teaching s t e r e o c h e m i s t r y (for e x a m p l e of t h e [Pt19(C0)12(fi2 - CO)10l4- tetraanion),' can be made easily by using a sealed empty envelope. The steps (illustrated in the figure) are given below.2 (1) The first figure shows the starting configuration,which is produced by steps 1-7 of the previous article.3 (2) A horizontal line, perpendicular to the left-hand side of the envelope at D, is drawn so that it intersects the two Lines (K)
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(14) On the hack of the envelope, the points corresponding to the ooints U'. W'.R'. S'.R. S. U. and W. are marked U'*. W'*.R8*. k*. R*. - ,. . . . [I*. . , Ad -~ - ~*.'reioectiveiv. . (15) Oblique lines are drawn to shade the 10 isosreles triangles (U'H'W', W'S'X', RUW, and SWX on the front; IP'R'*W'., IIV'S"X', R'Lr'W', and S'M"X on the hack; and C"Q'Lr" and QUU* on both sides). (16) The envelope is folded both backward and forward along the lines Q'T, QT, (h7(i.e., R'*R*), (M) (i.e., S'*S*), Q'U (i.e., QU ' *'), U'R' (i.e., U'*R'*), R'W' (i.e., R'*W'*), W'S' (i.e., W'*S"). S'X' (i.e..S'*X')... QU (i.e.. . QU*). UR he.. U'R1).RW .. (i.e.,~;*), wstie., W'S*), and's^ (i.k., Six): (17) The right- and left-hand sides of the envelope are pushed toward each other so that the five lines (QQ ' . R'R, S'S, S'*Sa, and R'*R*) form the five sides of a pentagonal prism. (18) The five points U', W', X', W", and U'* are pushed together and the shaded, creased triangles (U'R' W', W'S'X', WT*S'*X', Uf*R'*W'*, and U'Q'U'*) are folded inside. The sides are taped together to produce the upper pentagonal pyramid. (19) The five points U, W, X , W*, and U* are pushed together and shaded creased triangles (RUW, SWX, S*URXa, R*UaW*, and QUU*) are folded inside. The sides are taped together to produce the model given in the title.
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(7) The left upper part of the envelope is folded down a t Q so that the point D falls on the line ( a . The corresponding point is marked U. (8) The left upper part of the envelope is unfolded. (9) A horizontal line, perpendicular to the line (4at U, is drawn so that it interseets the left- and right-hand sides of the envelope and the line (L)at V ,X, and W, respectively. (10) The lower part of the envelope is folded u p along the line DP. On the original front of the envelope, the points corresponding to the points Q, R, S, T, V, U,W, and X , are marked Q', R', S', 2". V'. . U'. . W'. . and X'. resoeetivelv. (11) he lower part of theknvblupe isinfolded. (12) The upper pan of the envelope is cur off along the line V'X'. (13) The lower part of the envelope is cur off along the line VX.
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Washecheck, D. M.: Wucherer. E. J.; Dahl. L. F.; Ceridti, A.; Longoni. G.; Manassero, M.: Sansoni, M.; Chini, P.; J. Am. Chem. Soc. 1979. 101..6110. For a history of the Yamana methods of making various oolvhedral
models from a business envelope s e e Australian ?%emistr);~esource B w k . Australian National Chemistry Week: Bathurst, 1986; p 10. Yamana. S., "An Easily Constructed Pentagonal Pyramid Model," J. Chem. Educ. 1988,65,301.
Volume 66
Number 4
April 1969
303
