This text covers the fundamental topics in Environmental Chemistry, Introduction to Environmental Sciences and Environmental Physicochemistry for students of Chemistry, Chemistry and Environmental Technology, Chemistry, Biochemistry, Biotechnology and Pharmacy, Chemical Engineering as well as related Sciences. The text is based on three central aspects: the macroscopic description of the phenomena, the establishment of correlations between the observed phenomena, as well as the formulation of hypotheses, models and theories to explain the experimental facts. It seeks to show the limitations implicit in the models, in order to establish a dynamic between what is observed and what is intended to be described in terms of them, applied to different environmental scenarios.