Electronegativity Effect on C-Halogen Bond Stretching in Alkyl Halides at Higher Education Level

Abstract

Electronegativity is an intrinsic parameter of each chemical element that influences the response, chemical reactivity, polarity, as well as the attraction between molecules among other effects. In this sense, a didactic strategy was developed for teaching at the undergraduate level to determine the effect that electronegativity has on the vibration response of the C-Halogen bond in a molecule, through a practical experience that involved on the one hand the technique of infrared spectrophotometry and organic molecules with the presence of halogen atoms. The didactic strategy was applied to a group of students of the bachelor’s degree in industrial chemistry, which was divided into teams of 5 students who worked based on cooperative learning and with problem-based learning support, they were studying spectroscopy and who had previous knowledge of the infrared spectroscopy technique. After carrying out, the experiment and with the results obtained, the students were able to conclude that due to the strength and distance of the bond between halogen and carbon, the value of the wavenumber (cm^-1) is modified, concluding that in shorter bonds a greater energy is required for it to be stretched and in longer and weaker bonds as in the case of Iodine these are stretched to a lower wavenumber. This allowed students to understand this phenomenon and the dependence of electronegativity, bond length, and bond strength on a specific response observed using infrared spectroscopy.