Introduction

The phonetic similarity of the sound of a trivial name of a chemical substance to the name of the element or its species can easily lead to a false idea of the actual composition or structure of a compound. In the chemical community, however, trivial and totally unsystematic names are preferred to the admittedly complicated systematic names. There often, however, is still some similarity of names but in most cases, the only common property is that these compounds are "chemicals". They often do not even share origin, e.g., "inorganic" as opposed to "organic". This seeming contradiction becomes even more apparent when thermochemical information such as the heat (or more properly enthalpy) of formation is also considered. We note that there are over 108 known chemical species, and many more if one includes DNA and protein sequences and fragments. In contrast, there are calorimetrically derived thermochemical data for not many more than 104, and certainly less than 105, species. The extremely challenging demand for careful measurements on highly pure samples has resulted in very few contemporary laboratories whose goal and activity are to measure and understand these quantities. Relatedly and admittedly, one of the most important research activities of the authors has been the understanding, but never the measurement, of the quantities that arise from these studies.

In the present study in Structural Chemistry, we continue our efforts to find a compound with a subjective phonetic sound similarity for each element of the periodic table. In the first part [1] (of four parts), we discussed the elements from hydrogen (H) to argon (Ar) (Z = 1 to 18). In the second part (of four parts), we discussed the elements from potassium (K) to xenon (Xe) (Z = 19 to 54) [2]. In the current Part 3 of this review, we discuss cesium (Cs) to radon (Rn) (Z = 55 to 86). Given our interest in thermochemistry, the question arises as to how we chose which compounds to consider. In most cases, primary sources were used as reference sources for thermochemical data; however, in some cases, secondary sources, i.e., the “Domalski compendium” [3], the “Wagman et al. compendium” [4], or the “Pedley compendium” [5] were used. It is to be acknowledged that the “missing” data are quite ancient and we admit surprise at its absence in these sources. We wish to encourage the remeasurement of these enthalpies of formation. Given there are many “exotic” compounds that have been recently synthesized and for which there are no measurements at all, we welcome the desired enthalpies of formation and any other thermochemical data about them.

The reader may suspect that there are alternative choices of compounds with appropriate names, and some even with the desired calorimetric measurements. Many of these compounds, for instance, are of contemporary interest to the pharmaceutical and agricultural chemistry communities. However, even with the use of “generic” names, we abstain from the use of these species and associated trivial and unsystematic names because we are loathe to “advertise” one corporation over another.

We acknowledge now our interest in etymology, but it is our view that giving the word origins for unsystematic and trivial names would be an excessive diversion of our activity. In addition, in many cases, we do not know the desired origin, nor do we know how to find it. We note a lengthy and thorough multipart recent study on the origin of the names of the elements [6,7,8], and while we laud this study, we do not wish to emulate it for the names of the compounds.

With the above discussion of our disclaimers as to the authors’ thermochemical interests, choice of compounds, and etymological concerns, we now refer the reader to Table 1 and conclude the current paper by beginning with Part 4 for the element francium (Fr) to oganesson (Og), Z = 87 to 118.

Table 1 Elements from cesium (Cs) to radon (Rn) (Z = 55 to 86) arranged according to the increasing order of atomic number accompanied with examples of compounds with ‘similarly’ sounding names but entirely different composition
Full size table

Conclusions

Compounds that have similar phonetic semi-systematic or trivial names to that of the elements have been studied in terms of their composition, structure, and chemical energetics. This review, which follows part 1, revels even deeper differences between expected and actual composition of compounds. Nevertheless, what it is not surprising is that, semi-systematic or trivial names are widely preferred by the chemical community because of complicated nature of systematic names.