Is electron's probability density. This is normally introduced bv askine. "Does the electron soend the same amount of time ai all po&s in the volume?"?he students are asked to consider the tvpe of plot that would he derived if the instantaneous posiikms o? the electron were recarded overa long period of time. Most students are able to see that the electron spends more time in some locations than others and that if these positions were plotted, the results would be a spherical cloud which is darker in some areas than others due to the higher probability of the electron occurring in those locations. We are well aware of the approximate nature of this treatment and of the model. We can not claim originality for its design since we are probably not the only chemists who have spent time in a Keno lounge. Rather, we present the idea because it has proved to be an inexpensive instructional aid for presenting an abstract concept and it may be helpful toothers. We will be most happy to provide any additional details which others may require. ~~
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A Modified Thermit Lecture Demonstration S ~ s l l l n BY: ~o George B. Kauffman California Slate University. Fresno Fresno. CA 93740 CIEWEO BY: Marvln K. Kemp Universiw 01 Tulsa Tulsa. OK 74104
T h e recent note on the thermit lecture demonstration' prompts me to report some modifications of this well-known d e m o k r a t i o n that 1 have used for the past two decades to make ic more dramatic and interesting for students. I tm have employed the KXlnO4-glycerin ignition mixture (which, incidentally, seems to work hetter if the finely.powdered over the .. elvcerin rather than the reverse) KXlnO,. is sorinkled . . and :
