### The Number of Possible Elements and Mendeléeff's "Cubic" Periodic System

A. van den Broek

*Nature,* vol. 87

20 July 1911, pg. 78

According to Rutherford's theory of "single scattering" ("On the Scattering of a and b Particles by Matter and the Strucure of the Atom," *Phil. Mag.*, May, 1911), and to Barkla's "Note on the Energy of Scattered X-Radiation" (*ibid.*), the numbers of electrons per atom is half the atomic weight; thus, for U, about 120. Now, a reconstruction of Mendeléeff's "cubic" periodic system, as suggested in his famous paper "Die Beziehungen zwischen den Eigenschaften der Elemente und ihren Atomgewichten" (*Ostw. Klass.*, No. 68, pp. 32, 36, 37, and 74), gives a constant mean difference between consecutive atomic weights = 2, and thus, from H to U, 120 as the number of possible elements (van den Broek "Das Mendelejeff'sche 'Kubische' Periodische System der Elemente und die Einordnung der Radioelemente in dieses System," *Physik. Zeitschr,* 12, p. 490). Hence, if this cubic periodic system should prove to be correct, then the number of possible elements is equal to the number of possible permanent charges of each sign per atom, or to each possible permanent charge (of both signs) per atom belongs a possible element.

Go to van den Broek's scond letter on this topic.

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