Para além das fronteiras da química: relações entre filosofia, psicologia e ensino de química

The concepts of molecule and of molecular structure are so central to understand chemical phenomena that seems to be no doubt about the uniqueness of its meanings. Nevertheless, the idea that the world exhibits a multiform structure and that to different spheres of the world correspond different ways of knowing (Berger & Luckmann, 1967) has received support from different areas of scientific inquiry. Bachelard (1940, 1982) showed that a single philosophical doctrine is not enough to describe all the different ways of thinking when we try to explain a single concept. Wooley's question about the possibility of deducing the concept of molecular structure from quantum theory (Wooley, 1978) strengthened the feasibility of thinking the concept of molecule as a profile that encompasses different meanings. Moreover, research on students' learning of scientific concepts have brought to light that students use several ideas to explain scientific and everyday phenomena which are different from those learned in formal schooling. These ideas are not extinguished or replaced by scientific concepts, despite the efforts to do so in science classes. The common sense and scientific ways of understanding and talking about reality seems to be complementary in the same sense of the Bohr's complementarity (Halliday & Martin, 1993). So, we have to include in our profile of the concept of molecule not only scientific but also common sense zones. Drawing from Bachelard's notion of epistemological profile, from the history of science and from the research on children's ideas in science, we have developed the idea of a conceptual profile and used it to analyse basic scientific concepts, such as the concepts of matter and physical states of matter (Mortimer, 1995) and to investigate new ways to teach them. In the present paper, we will discuss the zones that might constitute a conceptual profile of molecule. The need of complementary views to account for the molecular structure in different contexts bring important issues for understanding and teaching chemistry, which will be discussed further in the article.

Curso noturno de licenciatura em química: uma década de experiência na UFMS

This is a study concerned with determining the efficiency in training high school chemistry teachers in the Federal University of Mato Grosso do Sul. The analysis was based on the following information, i.e., the opinion of the students who were enrolled in the course, university entrance examinations and academic performance. We reach the conclusion that the goal was partially achieved in training high schools' teachers. Further suggestions and strategies are proposed in order to overcome the problems.

Simulação da Química da Atmosfera Poluída por Automóveis Movidos a Álcool

Numerical modeling studies of urban atmospheres were performed with a photochemical box submodel which incorporates primary emission rates, temperature and solar irradiance rate coefficients. Actinic flux calculations were made for an appropriate latitude for Rio de Janeiro and initial concentrations and emission rates were taken from experimental data. The relative importance of individual reactions is discussed as well as the effect of enhanced aldehyde emissions from vehicles using ethanol and ethanol-containing fuel.

Modelagem Molecular: Uma Ferramenta para o Planejamento Racional de Fármacos em Química Medicinal

The molecular basis of modern therapeutics consist in the modulation of cell function by the interaction of microbioactive molecules as drug cells macromolecules structures. Molecular modeling is a computational technique developed to access the chemical structure. This methodology, by means of the molecular similarity and complementary paradigm, is the basis for the computer-assisted drug design universally employed in pharmaceutical research laboratories to obtain more efficient, more selective, and safer drugs. In this work, we discuss some methods for molecular modeling and some approaches to evaluate new bioactive structures in development by our research group.

Algumas Considerações sobre a Regra de Hund e a Estrutura Eletrônica de Átomos no Ensino de Química

Hund's maximum multiplicity rule as stated in most elementary and intermediate level textbooks on general and inorganic chemistry and usually taught at the college and undergraduate level is incorrect. It is true that electrons entering a subshell of an atom tend to occupy the orbitals singly as far as possible but not necessarily with parallel spins. Also, proper definitions and correct use of terms like configuration, microstate, spectroscopic term, level and state are essential if confusion on the part of the student, especially the beginner, is to be avoided.

Multicomutação e amostragem binária em análise química em fluxo: determinação espectrofotométrica de ortofosfato em águas naturais

A flow system based on multicommutation and binary sampling process was developed to implement the sample zone trapping technique in order to increase the spectrophotometric analytical range and to improve sensitivity. The flow network was designed with active devices in order to provide facilities to determine sequentialy analyte with a wide concentration range, employing a single pumping channel to propel sample and reagents solutions. The procedure was employed to determine ortophosphate ions in water samples of river and waste. Profitable features such as an analytical throughput of 60 samples determination per hour, relative standard deviation (r.s.d.) of 2% (n = 6) for a typical sample with concentration of 2.78 mg/L were achieved. By applying the paired t-test no significant difference at 95% confidence level was observed between the results obtained with the proposed system and those of the usual flow injection system.

Perfil sócio-econômico dos alunos, repetência e evasão no curso de Química da UFMG

This paper describes a study about the causes for the dropout of chemistry undergraduate students at UFMG in the nineties. The students' social and economic profile was outlined. It was observed a correlation between family income and academic performance and between failure at the beginning of the course and the dropout, but it seems that family income doesn't affect markedly the dropout. The endogenous and exogenous causes contribute equally for the dropout. The authors suggest that the dropout could be significantly reduced if the endogenous causes such as large classes, inadequate curricula and programmes, poor teaching and the unapproachability on the part of the teachers were faced.

As "Disquisitiones" do naturalista Arruda da Câmara (1752-1811) e as relações entre a Química e a Fisiologia no final do Século das Luzes

This work is intended to rescue the field of validity of the "Disquisitiones" by the naturalist Arruda da Câmara placing them in the scientific and historical context of the end of the "Century of Light". Thus, a tentative is made here to reconstruct the debate established among the several theories that served as background of the relationships between Chemistry and Physiology of that time. In the present work is presented by the first time an integral translation of the "Disquisitiones" and a biographical resume of the naturalist in the historical context of his epoch in Northeast Brazil, especially in Pernambuco.

Análise de extratos de plantas por CCD: uma metodologia aplicada à disciplina "química orgânica"

extracts of the regional plants Annona squamosa and Annona muricata were analysed by silica gel thin-layer chromatography using adequate systems of solvents and spray reagents. Carbohydrates, amino acids, alkaloids, flavonoids and terpenoids were detected in both species. These data agree with those on the literature about phytochemistry of the Annonaceae.

Conhecimento escolar em química: processo de mediação didática da ciência

xThe aim of this article is to present a contribution of the school knowledge research to Chemistry Teaching. The object of research is school knowledge on physical sciences, considering the existence of a rupture between scientific knowledge and everyday knowledge. The differences between analogies and metaphors and the process of didactic mediation were thoroughly examined. The conclusion is that the process of didactic mediation is built on their own cognitive configurations, which not always make public the private scientific knowledge to certain social groups.

Superordem corniflorae: química, etnofarmacologia e farmacologia

Corniflorae (sensu Dahlgren, 1980) is a superorder of the Angiospermae formed by the orders Fouquieriales, Ericales, Eucommiales, Sarraceniales, Cornales and Dipsacales, comprising 50 families with more than 7000 cosmopolitan species. Many of these species are used in tradicional medicine and some of them had their pharmacological activities confirmed. The chemistry of these plants is very diversified. Iridoids, triterpenoids and flavonoids were used as taxonomic markers.

A química da família bombacaceae

The Bombacaceae family consists of 28 genera and 200 species. This work reviews all the chemical studies carried out on the members of this family, and shows that only ten genera were investigated. From this review it can be seen that no particular class of chemical metabolites is ubiquitous in this family.

Currículo de licenciatura em química da universidade de brasília: uma proposta em implantação

This article presents the conception, principles and academic structure of the evening course leading to the formation of a Licentiate in Chemistry, at the University of Brasília. The curriculum has been carried out since the beginning of 1993. This curriculum has as its basic axis the graduation of future teachers integrated with the conceptual formation in Chemistry. Interdisciplinary actions are planned between the Chemistry Department, the Psychology Institute and the Faculty of Education so as to provide mechanisms which would allow the licenciate to acquire teaching experience along the course.

O impacto do PADCT na química e engenharia química

Among all activities related to the management of science and technology in Brazil, program monitoring and evaluation is certainly one of the less developed and most needed. There are no universal methodologies that can be applied. In essence programs can be evaluated by relating their achievements to pre-established goals. A second strategy is to compare programs similar in nature, utilizing as reference common indicators. Finally programs can be evaluated by their socio-economic impact comparing investments to outcomes. All strategies mentioned require appropriate program design monitoring and expert independent evaluation. In Brazil as in many other countries including developed ones this activity is complicated by the fact that programs vary widely in their scope and goals. In Brazil program designs often do not specify clearly their purposes and output indicators, many are not monitored properly which makes evaluation difficult. Consequently science and technology programs are difficult to be compared to each other, and even evaluated on the basis of pre-established goals. In PADCT monitoring and evaluation proved to be the most challenging activities. Two lessons however were learnt. One is that the process of monitoring and evaluation has to be continuously exposed to criticism to be perfected; and the second is that the evaluation process must not be exhausted shortly after investments since translation of scientific knowledge into industrial applications may prove to be a lengthy process. In this exercise we certainly do not pretend to evaluate the QEQ subprogram but to organize some of the information produced by different sources related to this subject, including the PADCT administration. We use somewhat each strategy described: compare the outputs of the QEQ to predetermined proposed goals (particularly in PADCT II), compare the QEQ to other PADCT subprograms, and specify some outputs in terms of technological and industrial applications. Finally, we utilize this opportunity to discuss science and technology M&E in general and the complexity of developing this area in Brazil.