The Discovery of Germanium

One of the early triumphs of the Mendeleef Periodic Table was the prediction of the properties of elements which were then unknown. Fifteen years before the discovery of germanium in 1886, Mendeleef had predicted that the element which he called ekasilicon would be discovered, and he had also correctly predicted many of its properties. In Table 1.8 his predicted properties are compared with the corresponding properties actually found for germanium. 

Further confirmation came when Lars Nilson (1840-1899) announced the discovery of scandium (after Scandinavia), in 1879, which matched Mendeleev s eka-boron, and Clemens Winkler s (1838-1904) announcement of the discovery of germanium (after his home country of Germany) in 1886 which matched eka-silicon. Mendeleev s theoretical position triumphed, and his table began to be accepted as a genuine insight into the order of the material world. 

Although the book was published after the discovery of germanium, the lack of past examination questions imphes examiners had not yet seen periodicity as important, so the author needed to redress this absence. 

Gallium [7440-55-3] atomic number 31, was discovered through a study of its spectral properties in 1875 by P. E. Lecoq de Boisbaudran and named from Gallia in honor of its discoverer s homeland. The first element to be discovered after the pubHcation of Mendeleev s Periodic Table, its discovery constituted a confirmation of the Table which was reinforced shordy after by the discoveries of scandium and germanium. 

Interface states played a key role in the development of transistors. The initial experiments at Bell Laboratories were on metal/insulator/semiconductor (MIS) stmctures in which the intent was to modulate the conductance of a germanium layer by applying a voltage to the metal plate. However, only - 10% of the induced charges were effective in charging the conductance (3). It was proposed (2) that the ineffective induced charges were trapped in surface states. Subsequent experiments on surface states led to the discovery of the point-contact transistor in 1948 (4). 

And Maher goes on explicitly to underline the conclusions about confirmatory weight that he sees as illustrated by this episode. He claims that Mendeleev s prediction of the existence of the third of the new elements, eka-silicon (aka germanium), was initially regarded as quite unlikely to be true but then later, with the discovery of the first two new elements (gallium and scandium), confidence in the prediction of the existence of the third new element became so high that its eventual empirical confirmation was widely regarded as a matter of course. Maher writes ... 

We have already pointed out that Maher cites no historical evidence for this dramatically increased confidence beyond the award of the Davy Medal and we have shown that the citation for that award tells against his claim rather than for it. But what if—for all the lack of evidence—chemists at the time did regard the eventual discovery of germanium as a matter of course Would they have been wise to do so ... 

The application of these techniques has led to the discovery of a number of organometallic species of arsenic, tin, and antimony in the marine environment. Germanium has not been observed to form organometallic compounds in nature. Some aspects of the geochemical cycles of these elements which have been elucidated by the use of these methods are discussed. 

In the late 1980s Bedard et al. reported the discovery of microporous metal sulfides, based on germanium (IV) and Sn (IV) sulfide frameworks [52]. 

The discovery of gallium was followed by the discovery of scandium (Mendeleev s eka-boron) in 1879 and of germanium (eka-sili-con) in 1886. The new elements had the approximate atomic weights and properties that Mendeleev had predicted. The scientific world was astonished. It is probably safe to say that before Mendeleev s predictions were confirmed, no chemist would have believed that the properties of unknown elements could be predicted with such accuracy. 

Th. Richter, said Weisbach. had already determined the silver content in two concordant blowpipe analyses as 73V2 per cent. My colleague Cl. Winkler then obtained as the mean of several experiments 75 per cent of silver and 18 of sulfur, hence a loss of 7 per cent. This loss, after long remaining inexplicable, finally led, in the course of further investigations, to the discovery of a new element similar in properties to arsenic or antimony, which Winkler, the discoverer, on February 1st named germanium (28). 

After commenting on the discovery of gallium, scandium, and germanium (eka-aluminum, eka-boron, and eka-silicon), D. I. Mendeleev had written in 1891, I foresee some more new elements, but not with the same certitude as before. I shall give one example, and yet I do not see it quite distinctly (7). He had then proceeded to describe an undiscovered dvi tellurium with an atomic weight of about 212. Since polonium resembles tellurium and has an estimated atomic weight of about 210, it is probably the realization of Mendeleev s dvi tellurium. ... 

Perfection especially is required on the silicon surface. A 100 surface of silicon contains 6.8 x 1014 atoms/cm2. Surface defect densities must be less than one part in 105—105 defects/cm2 for satisfactory MOSFET operation. In fact, the discovery of the original point contact transistor was only possible because the native oxide on single-crystal germanium has surface defect densities less than one part in 104. Good silicon devices required the discovery (10) that the thermal oxidation of silicon could produce an excellent Si—Si02 interface. 

Ge(C2H5)4 deserves some prominence as it was prepared only one year after the discovery of elemental germanium by Clemens Winkler at the Bergakademie Freiberg in Germany [30]. 

Mendeleeff had found himself forced to leave a number of places in his system unoccupied. He believed correctly that elements as yet unknown would find their places in these gaps. His accurate prediction of the properties of these missing elements, which he named eka-boron, eka-aluminium and eka-silicon, was brilliantly confirmed a short time later by the discovery of scandium (21), gallium (31) and germanium (32). The Inert (or Rare) Gases discovered later by Rayleigh and Ramsay could also be readily included in the system. Again, the latest, non-radioactive elements discovered, hafnium (72) [Von Hevesy and Coster, (1923)] and rhenium (75) [Nod-... 

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