This manuscript (i) presents the Chemical Concepts Inventory (CCI), an inventory that faculty can use to judge for themselves the extent of several common alternate conceptions among their students; (ii) demonstrates that students come to general chemistry with a variety of the alternate conceptions described in the chemical and science education research literature; and (iii) shows that a traditional general chemistry course results in only modest improvements in understanding of basic concepts. The incorrect concepts include inappropriate ideas about atoms and molecules, microscopic behavior, heat and temperature, chemical formulas, gases, and other qualitative concepts—concepts that form the foundation of several topics of first-semester college chemistry.The inventory is a multiple choice instrument composed of one- and two-tiered nonmathematical questions based on alternate conceptions reported in the science education literature. Administration of the inventory before the first semester of a two-semester general chemistry course for science and engineering majors confirmed that students hold many alternate conceptions in diverse areas of chemistry prior to the course. An administration of the inventory at the beginning of the second semester indicated that these students retained many of their alternate conceptions through a semester of instruction.
Extensive chemical, spectrophotometric, and x-ray structural studies have shown that trivalent rhenium is strongly homophilic-that is, it tends to form bonds to other Re(111) atoms-and it forms at least three different series of [ReX(4)](n)(n-) complexes. The mononuclear, square complex, [ReBr(4)](-), adds two water molecules to give trans-[ReBr(4)(H(2)O)(2)](-). The binuclear complexes [Re(2)Cl(8)](2-) and [Re(2)Br(8)](2-) have strong Re-Re bonds, unsupported by halide bridges. The trinuclear species, [Re(3)X(12)](3-) or Re(3)X(9)L(3), contain the triangular Re(3)X(9) clusters. Use of ReCI(3) appears always to lead directly to products containing Re(3)Cl(9); this unit exists in ReCl(3) itself and does not appear to be kinetically labile. The [Re(2)X(8)](2-) ions are obtained by reduction of ReO(4)(-) in aqueous HCl or HBr. Salts of [ReBr(4)(H(2)O)(2)](-) can be obtained directly from solutions of ReBr(3) in HBr along with numerous other compounds, some containing trinuclear clusters.
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