In the Periodic Tables the transition from atoms to double-charged cations is accompanied by alterations in the composition of s and p blocks and reciprocal location of blocks, as well as by changes in the composition and length of periods. We have previously described the relationship between the atom properties and the total number of differentiating electrons. This paper demonstrates that, despite the above transition-related alterations, this relationship is also valid for the description of the properties of double-charged cations. This (...) can be exemplified by the dependence of the ionization energy on the total number of p electrons in p block, d electrons in d block, and f electrons in f block. Furthermore, a single periodic equation is sufficient for the description of properties of all of double-charged cations from each block. (shrink)

Chemical ideas about the diversity of matter in terms of elements and compound substances and their transformations have been pivotal to any scientific or pre-scientific approach ever since. From ancient natural philosophy and alchemy to modern 19th-century chemistry, these ideas were made both the basis of philosophical systems and the target of critical reflection. After temporary interruption, when modern philosophy of science materialized as a discourse on mathematical physics, philosophy of chemistry emerged anew in the 1980s and is now a (...) flourishing field in which philosophers, chemists, and historians of chemistry are engaged. While many of the old philosophical issues have been rediscovered and discussed, new issues have appeared due to shifts of general philosophical foci, alliances with historians and sociologists of science, and the changes of chemistry and its role in society. (shrink)

The concept of projection from one space to another, with a consequent loss of information, can be seen in the relationships of gene to protein and language description to real situation. Such a transformation can only be reversed if extra external information is re-supplied. The genetic algorithm embodying this idea is now used in applied mathematics for exploring a configuration space. Such a dialectic – transformation back and forth between two kinds of description – extends the traditional Hegelian concept used (...) by Engels and others of change as resulting from a resolution of the conflict of two opposing tendencies and provides for evolution of the joint system. (shrink)

This paper presents a numerical study of the reaction A ↔ B in the presence of an intermediate and destabilizing step in its dynamics. After introducing a direct autocatalytic destabilizing process, namely quadratic autocatalysis ) and cubic autocatalysis ), a thermodynamic analysis of the evolution of the reaction in closed and open systems was performed. In addition, the Gibbs free energy, the thermodynamic affinity, and the entropy generation of the overall reaction were evaluated for each of the autocatalytic steps, in (...) order to analyze the behavior of these thermodynamic quantities when the system moved towards equilibrium or towards oscillatory non-equilibrium states. (shrink)

Mendeleev’s failure to represent the periodic system as a continuum may have hidden from him the space for the noble gases. A spiral format might have revealed the significance of the wide gaps in atomic mass between his rows. Tables overemphasize the division of the sequence into ‘periods’ and blocks. Not only do spirals express the continuity; in addition they are more attractive visually. They also facilitate a new placing for hydrogen and the introduction of an ‘element of atomic number (...) zero’. (shrink)

This chapter contains sections titled: Introduction What is Chemistry about? Is Chemistry Reducible to Physics? Are There Fundamental Limits to Chemical Knowledge? Is Chemical Research Ethically Neutral? Conclusion References.