The classification of chemical substances is a concept little explored in Chemistry teaching literature and in Chemistry textbooks at higher and secondary levels. The aim of this paper is to discuss theoretically the importance and contributions of this concept for teaching and learning Chemistry. The History of Chemistry reveals that the chemical criteria for classifying materials came up with the modern concepts of chemical element and chemical reaction, which gave rise to the notion of chemical similarity. Later, such similarity was related to molecular structure through functional groups. The classes of substances are related throughout chemical reactions, during which substances of given classes are transformed into substances of other classes, constituting a wide network. The classification of chemical substances can contribute to the intellectual development of Chemistry students, in order to study it, it becomes necessary to understand its theoretical foundation, as well as its characteristics of objectivity, completeness, simplicity and prediction. In this sense, one can contribute to the stimulation of perception, attention and abstraction that are typical of the chemical ways of thinking and communicating necessary for learning the chemical concepts linked to classification.
Keywords:
classification of chemical substances; chemical similarity; chemical education
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