From Water to H2O: Using the Human Dimension of Science To Teach the Nature of Science

The long and complex history to define the composition of water as H2O is summarized. This case study could be useful not only to introduce the history of chemistry in the classroom but also to teach the basic tenets of the nature of science (NOS). Water has been present in several turning points in the history of chemistry such as the first steps of pneumatic chemistry, the chemical revolution, the beginning of the atomic theory, early electrochemistry, and the theory of ionic dissociation. The human dimension of science has been chosen as one of the numerous possibilities offered by the water case study to teach NOS. For this purpose, topics involved in the history of water such as Van Helmont's "tree experiment", the "water controversy", the revival of Avogadro's hypothesis by Cannizaro, some scientific highlights of Arrhenius and Laurent, and the identification of oxygen are analyzed.