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)

The basis of the Periodic Table is discussed. Electronic configuration recurs in only 21 out of the 32 groups. A better basis is derived by considering the highest classical valency (v) exhibited by an element and a new measure, the highest valency in carbonyl compounds (v*). This leads to a table based on the number of outer electrons possessed by an atom (N) and the number of electrons required for it to achieve an inert (noble) gas configuration (N*). Periodicity of (...) these is nearly complete. The new basis helps to settle the question of the best form of table and related issues. (shrink)

This article updates the author’s 1982 argument that lutetium and lawrencium, rather than lanthanum and actinium, should be assigned to the d-block as the heavier analogs of scandium and yttrium, whereas lanthanum and actinium should be considered as the first members of the f-block with irregular configurations. This update is embedded within a detailed analysis of Lavelle’s abortive 2008 attempt to discredit this suggestion.

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)