From cathode rays to alpha particles to quantum of action: A rational reconstruction of structure of the atom and its implications for chemistry textbooks

Abstract

Research in science education has recognized the importance of the history and philosophy of science. Given this perspective, it is important to analyze chemistry textbooks, at the freshman college level, to determine the degree to which they deal with recent developments in the history and philosophy of science. This study has the following objectives: of a (a) elaboration framework, based on a rational reconstruction of developments that led to the formulation of atomic models by Thomson, Rutherford, and Bohr; of eight criteria based on the framework (b) formulation that could be useful in the evaluation of chemistry textbooks; and of the textbooks (c) evaluation based on the criteria. Twenty-three textbooks were evaluated on the eight criteria. Results obtained show that most textbooks emphasize experimental details based on observations, leading to the presentation of scientific progress as a rhetoric of conclusions, based on irrevocable truths. Such an understanding lacks the conceptualization of the heuristic principles that led the scientists to design and interpret their experiments. For example, in the case of J. J. Thomson's work, besides the experimental details of cathode ray experiments (emphasized by most textbooks), the "heuristic principle" involved the testing of rival hypotheses, namely a determination of the mass-to-charge ratio would have helped to identify cathode ray particles as an ion or a universal charged particle. Most textbooks presented the experimental details, without the conceptualization that progress in science is based on competing frameworks of understanding that clash in the face of evidence. It is concluded that textbooks should emphasize not only the experimental details but also the "heuristic principles" required to "structure inquiry."

Inquiry in science education: International perspectives

“…The "Programa de Articulación" (ME, 1990) clearly states that the objectives of the unit on atomic structure are to study, among others, the contributions of Dalton, Thomson,Millikan,Rutherford,and Bohr (p. 38). This is a welcomed emphasis: Recent research in science education indicates that the historical study of atomic structure serves as a useful context for helping students investigate and internalize some consensus views about NOS, such as the tentative nature of scientific theories, and develop fundamental understandings about the nature of inquiry (Niaz, 1998(Niaz, , 2000. Interestingly, in the section on methodological suggestions for teachers, the ME document states that "it is not necessary .…”

Facilitating Chemistry Teachers’ Understanding of Alternative Interpretations of Conceptual Change

“…Readings: 1) Matthews (1994); 2) Adúriz-Bravo, Izquierdo, & Estany (2002); 3) Solbes & Traver (1996, 2001; 4) Leite (2002); 5) Niaz (1998) Sanger & Greenbowe (1997); 9) De Posada (1999); 10) Kousathana & Tsaparlis (2002); 11) Niaz (2000b); 12) Campanario & Otero (2000). Unit 3: Conceptual change in learning chemistry.…”

“…Fuller, 2000, p. 212), then how can we elaborate and accept a certain sequence, steps, algorithms or rules for introducing conceptual change in the classroom. Based on Readings 5 (Niaz, 1998) and 6 (Niaz, 2000a) participants were particularly aware that most textbooks schematize progress in chemistry as based on the scientific method, that is, a scientist observes, experiments, and as a result enunciates a theory which is later confirmed repeatedly and finally the law is enunciated.…”

Do general chemistry textbooks facilitate conceptual understanding?

“…Thomson 3 measured mass to charge ratio in order to identify cathode rays as ions (if the ratio was not constant) or as a universal charged particle (constant ratio). Of the 23 textbooks (all published in U.S.A.) analyzed only 2 described satisfactorily the reason why Thomson decided to measure the charge to mass ratio 4 . Following is an example of a textbook that had a satisfactory presentation:…”