HIGH-SCHOOL NOTES ELBERT C. WEAVER1 Bulkeley High School, Hartford, Connecticut SUGGESTION
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N ORDER to visualize the idea of valence I supply
pupils with short lengths of copper wire and modeling clay of different colors. Using these materials, the pupils are required to construct simple models of compounds. Wads of clay represent atoms of elements and the wires the valence bonds. Each element has a separate color assigned. Within a short time pupils make satisfactory models of ternary compounds.DOROTHY G. HIMES,Polytechnic High School, Long Beach, California. INQUIRIES
H f . . , Agf. Later on the following equation is given without explanation for the apparent contradiction.
How is this inconsistency best explained to high-school pupils?-E. C. WEAVER. Many elementary chemistry textbooks show diagrams of the experiment of the burning of dry hydrogen in air. The water formed is condensed in an uncooled inverted beaker or under a bell jar. The water formed is shown to run down into a vessel below where i t collects in conside~able amount. In practice, the heat from the burning hydrogen warms this simple condenser to such an extent that only a little steam condenses to water. Are these diagrams unwarranted, or is some special technic needed to get amounts of water on such a condenser more than a mist?-E. C. WEAVER.
Why are the most active elements of the alkaline metal group a t the foot of Group I?-DOROTHY G. Hm~s. Why can safety matches be ignited by scratching them on window glass?-Do~o'rm G. HIMES. In the electrolysis of alumina in fused cryolite by the POLICY Hall process is elementary fluorine first liberated? If does this in turn replace oxygen?-E. C. WEAVER. The sponsors of this column will be glad to carry /SO'Most elementary chemistry textbooks give the fol- supplementary material which will be helpful to highlowing order for electrochemical replacement: K+. ., school teachers. We solicit questions, answers, helpful suggestions, items on educational advances, experiPresent address: Polytechnic High School, Long Beach, ments, local activity news, and.requests for material. California.
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