Identificação das dificuldades enfrentadas pelos alunos da 8ª e 9ª classe durante o tratamento de conceitos de Valência e Nox

Abstract

The present work has as objective to identify the difficulties presented by the 8th and 9th grade students during the treatment of concepts of valence and number of oxidation. For this purpose, we studied the difficulties that students have, using a series of interviews based on questionnaires to 6 Chemistry teachers and 390 8th and 9th grade students using the qualitative and quantitative method. In this work, the data collection instruments such as interviews, questionnaires, assistance to classes had the purpose of identifying the difficulties that the students present during the treatment of valence and Nox concepts. The result of the degree work allowed to identify the following difficulties in 8th grade students: lack of mastery of the concepts of atoms, chemical substance and chemical element. In the 9th grade, the Students' difficulties are linked to the assembly of chemical formulas through the its valences and oxidation reactions. In addition, 390 notebooks were evaluated of students and carrying out two diagnostic tests of the type of control activity systematic. From the evaluation of the 390 notebooks, 117 notebooks (30%) had notes that could be read, that is, those that were actually given by the teacher. Of the 390 students evaluated in the form of diagnostic tests of the type ACS, 296 were negative in the first test and 257 were negative in the second test, showing a slight increase in positive.