The reader of this textbook may be:
- a first-year student of multiple undergraduate programs that require basic and solid knowledge of Chemistry,
- a former graduate of departments where Chemistry was part of the curriculum and who, after years, wishes to come into contact with the subject of Chemistry in its broad sense again,
- a scientist from a very different area of specialization who has heard some general information about Chemistry (which, by the way, is sometimes mentioned inaccurately) and wants to acquire a first or regain a previous contact with the subject, or finally,
- someone who has only academic interest in the subject of Chemistry because they happened to hear or form the impression (which, again, is true) that the laws of Physics and Chemistry are the ones that govern, at least, the known Universe in an ultimate and inviolable way.

In this second edition, some small additions, rearrangements, and restructurings of texts have been made, but mainly, the interconnection between chapters has been noted in each case. When something is mentioned at a certain point that is described in more detail in another chapter, there is a corresponding indication in brackets. Furthermore, some corrections have been made to figures, so that they are clearer and more understandable. Finally, because the basic elements of the nomenclature of organic compounds are known (and considered) from high school, while there is a corresponding lag in the nomenclature of inorganic compounds, a relevant small concise guide is included in the appendix.