Ball and Stick Models for Oraanic Chemistrv " A set of baU and stick models large enough for organic chemistry lectures can be rather cumbersome. To overcome this we have devised s.set of balls and sticks which can be easily assembled into most of the molecules required during lectures. The set consists of duminum rods and polystyrene foam balls (oistern floats) into which sockets are fitted. These sockets are positioned according to the atom that the hall is to represent, and its state of hybridization. The sockets are made of aluminum drilled to accept the rods. The inner end of a socket is stepped and into this is epoxy glued the female portion of a carpet press-stud. The male portion of the pressatud is fitted into the drilled end of a rod. When a rod is inserted into a socket, once the end reaches the bottom it snaps into the carpet press-stud and is held in place, but it is nevertheless free to rot&. A washer is used to protect the press-stnd springs while glueing the socket into the ball. For r bonds the rods must be bent and to accommodate discrepancies greater clearances can be given, or a tightly wound spring incorporated into the md. The set has some useful properties. Rotating bonds rotate and a "boat" cyclohexane is flexible while a "chair" cyclohexane is rigid. An spa ball can be made that contains s frame of rectangular tubing, and inside this two of the sockets can be pivoted. Springs hold the sockets into the 109' angle but they can be made to increase this angle. Such a ball, assembled into a cyclohexme ring, and provided that pressure is applied to this ball alone, will allow'a cyclohexane to be changed from "boat" to "ch&' and back again. I must thank Mr. J. A. C. Baxter for his help while devising this ball.
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29 IYAN SMUTSAVENUE KRUGERSDORP, SOUTH AFRICA
MARTINTURNER
Volume 48, Number 6, June 1971
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407
