ABSTRACT
This chapter introduces some of the most fundamental concepts in the subject but prefaces this by a consideration of the nature of concepts and the kinds of concepts used in chemistry and taught in chemistry classes. Material objects are classed into types. This includes laboratory apparatuses where different items of equipment are seen as examples of petri dishes, watch glasses, thermometers, or indeed mass spectrometers. In the laboratory, the claim that a transition element has variable oxidation state would involve setting up a process where the oxidation state changes—that is, that one chemical compound of the element where it has a particular oxidation state is changed to another compound where it has a different oxidation state. In science there are normally definitions of technical concepts that set out in precise language what terms mean. One of the most fundamental ideas in chemistry is that of a chemical reaction.
