Interpretación submicroscópica de una propiedad física: ¿un problema resuelto?

Abstract

The aim of the work in hand is to come to conclusions as to why students relate boiling points of substances, such as halogens, with their atomic properties. The fact that this mistake has been observed in many evaluations brought about the implementation of a specific test to find out whether the students know that the boiling point is a macroscopic property of an elemental substance as in this case and not an atomic property.As the energy associated with a physical change is generally much lower than the one related to chemical bond breaking, the test also included a question aimed at finding out if students are able to differentiate between physical and chemical properties. It is thought that this could be helpful for them to relate boiling points to strength of intermolecular forces, and therefore overcome one of the most common alternative conceptions associated with this subject.Finally, in view of the different interpretations of the word "chlorine", used on an equal basis for the atom, the molecule and the elemental substance, the test provided a way to detect whether students that have already studied the subject of chemical bonds, are able to relate experimental data, state of matter and atomicity of chlorine; that is, that they can relate submicroscopic and macroscopic states.The analysis of the obtained results allows the identification of difficulties the students are faced with in this subject and the interpretation of possible causes.