999 resultados para livros impressos
Resumo:
This work evidences a survey conducted during a teacher professional qualification in Rio Grande do Sul, Brazil. This survey analysed the textbooks used by these teachers. The dynamics consisted of choosing the analytic criteria used by teachers, and adding new criteria for examining their difficulties and ways to choose textbooks. This article emphasises the problematics and difficulties teachers have to make choices and their loss of skills and authority to consider these books more profoundly.
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Despite of being used as thermodynamic criterion to rank alkene stability in a number of undergraduate textbooks, the heat of hydrogenation does not describe adequately the relative stability of disubstituted alkenes. In this work, both the heat of formation and the heat of combustion were used as thermodynamic criteria to rank correctly the stability of alkenes according to the degree of alkyl substitution and also in the disubstituted series (geminal > trans > cis). An operational model based on molecular orbital and valence bond representations of hyperconjugation is proposed to show how this effect can explain the order of stability of this class of compounds.
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The results of an exercise on electrochemistry for General Chemistry students are presented. The difficulty encountered by students in predicting the shift in the potential of the hydrogen electrode under non-standard conditions prompted a search in textbooks on how the subject is developed. Besides several instances of inconsistencies in defining the standard state, such as including the temperature in the definition, a number of incorrect depictions of the hydrogen electrode were discovered. Of the 28 General Chemistry books, 16 Physical Chemistry books and 24 Internet pages, 30, 20 and 46%, respectively, showed devices that would not work in practice.
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This paper aims at analyzing the history of science content of three general chemistry textbooks used in Brazilian universities: the translations of Kotz and Treichel's Chemistry & Chemical Reactivity, Atkins and Jones's Chemical Principles, and Garritz and Chamizo's Química. Results revealed different trends for the inclusion of history of science in chemistry teaching. Kotz & Treichel and Atkins & Jones used history mainly as curiosity and ornament. Garritz & Chamizo adopted the historical approach as one of the organizing axis of their textbook. Nevertheless, the historical content of the three textbooks may be criticized from current historiographical standpoint.
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Chemical imprinting technology has been widely used as a valuable tool in selective recognition of a given target analyte (molecule or metal ion), yielding a notable advance in the development of new analytical protocols. Since their discovery, molecularly imprinted polymers (MIPs) have been extensively studied with excellent reviews published. However, studies involving ion imprinted polymers (IIPs), in which metal ions are recognized in the presence of closely related inorganic ions, remain scarce. Thus, this review involved a survey of different synthetic approaches for preparing ion imprinted adsorbents and their application for the development of solid phase extraction methods, metal ion sensors (electrodes and optodes) and selective membranes.
Resumo:
This paper deals with the Brazilian textbooks of Chemistry from the XIX century to 1930. After presenting the science and its teaching contexts in Imperial Brazil and describing the first Chemistry textbook written by a Brazilian, the state of knowledge about these prime Brazilian books is presented. These works show the texts had strengths overlooked by current materials, a fact confirmed by analyzing textbooks from three authors from the period. The study concludes by compiling a list of 50 titles of early Chemistry books to help guide future research.
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The aim of this paper was to analyze the historical approaches to the periodic table in general chemistry textbooks used in Brazilian universities in the twentieth century. Textbooks were qualitatively analyzed according to the following criteria: position of the discussion about the periodic table in the book; presence or absence of a specific chapter on the subject; presentation of attempts to classify chemical elements before Mendeleev; presentation of the construction process of the periodic table by Mendeleev; identification of problems in the original table; discussion of Mendeleev's predictions about unknown elements; organization of the periodic table; periodic properties presented and discussed; and the enunciation of the periodic law. The analysis revealed different approaches at specific periods of the twentieth century, from more descriptive approaches to emphasis on attempts to explain the periodic table in terms of atomic orbitals. These changes point to different ways of understanding chemistry during the period studied.
Resumo:
Os livros didáticos são referência para professores e estudantes na construção das relações entre o ser humano e o meio ambiente, e devem proporcionar práticas capazes de despertar nos estudantes, a formação de uma consciência comprometida com a sustentabilidade socioambiental. O objetivo da investigação voltou-se à compreensão conceitual e metodológica da apresentação dos temas efeito estufa e aquecimento global nos livros didáticos de Geografia, aprovados pelo Plano Nacional do Livro Didático do Ensino Médio e sua interação com o debate articulado com educação ambiental. A análise dos livros se deu de acordo com as categorias: manual do professor, conceito relacionado à temática no texto e metodologia, esta última, direcionada à investigação do texto e de imagens associadas ao efeito estufa e ao aquecimento global. A investigação assumiu a dimensão qualitativa, com orientação centrada na modalidade documental. Os dados recolhidos para a investigação obedeceram ao método de análise de conteúdo, utilizando a técnica de análise temática categorial, proposta por Laurence Bardin. As considerações finais desta investigação apontam na direção de que, mesmo admitindo a relevância das avaliações promovidas pelo Governo Federal Brasileiro, os livros didáticos e seus manuais sugerem a necessidade de aprofundar reflexões que atestem contribuições para a formação de professores e estudantes comprometidos com a sustentabilidade do meio em que vivem.