Eka-elements

Later the eka symbolism was used also for the missing elements after manganese. Table 3.5 contains the years of discovery and the names of the eka elements. 

Eka-element After discovery called Discovery year... 

Practical analytical work in the laboratories continued as before, and it was exactly this continuity that facilitated an acceptance of Mendeleev s system. Furthermore, it was this analytical skill that converted the discoveries of the eka-elements to empirical facts and thereby converted the last remaining doubts concerning the periodic system into acceptance. Once the periodic system had been verified by analysis, the system could actually be used as a standard against which experimental results could be measured. If experimental work had given two considerably different atomic weights for one element, the place of the element in the periodic system could be used as an arbiter when choosing between them. 

Element 103, lawrencium, completes the actinides. Following this series, the transition elements should continue with the filling of the 6d orbitals. There is evidence for an element 104 (eka-hafnium) it is believed to form a chloride MCl4, similar to that of hafnium. Less positive evidence exists for elements 105 and 106 attempts (so far unsuccessful) have been made to synthesise element 114 (eka-lead). because on theoretical grounds the nucleus of this elemeni may be stable to decay by spontaneous fusion (as indeed is lead). Super-... 

Thus it can be seen that elements in and near the island of stabiHty based on element 114 can be predicted to have chemical properties as foUows. Element 114 should be a homologue of lead, that is, should be eka-lead, and element 112 should be eka-mercury, element 110 should be eka-platinum, etc (26,27). If there is an island of stabiHty at element 126, this element and its neighbors should have chemical properties like those of the actinide and lanthanide elements (26). 

Gallium was predicted as eka-aluminium by D. 1. Mendeleev in 1870 and was discovered by P. E. Lecoq de Boisbaudran in 1875 by means of the spectroscope de Boi.sbaudran was, in fact, guided at the time by an independent theory of his own and had been searching for the missing element for some years. The first indications came with the observation of two new violet lines in the spark spectrum of a sample deposited on zinc, and within a month he had isolated 1 g of the metal starting from several hundred kilograms of crude zinc blende ore. The... 

By the middle of the nineteenth century more than 60 elements were known with new ones continuing to be discovered. For each of these elements, chemists attempted to determine its atomic weight, density, specific heat, and other properties. The result was a collection of facts, which lacked rational order, Mendeleev noticed that if the elements were arranged by their atomic weights, then valencies and other properties tended to recur periodically. However, there were gaps in the pattern and in a paper of 1871 Mendeleev asserted that these corresponded to elements that existed but had not yet been discovered. He named three of these elements eka-aluminium, eka-boron and eka-silicon and gave detailed descriptions of their properties. The reaction of the scientific world was sceptical. But then in 1874 Lecoq de Boisbaudran found an... 

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 ... 

Mendeleev s real insight was revealed in his 1871 paper in connection with vacant spaces in the periodic table. He gave the provisional names eka-aluminium, eka-boron and eka-silicon [to the elements he expected to fill these gaps], (Ihde, 1964, p. 283)... 

Surely no one could believe that the 1871 predictions were more definitive than those of 1869 just on the basis that Mendeleev was prepared to give the elements names (eka-silicon, etc.) in the 1871 paper, while he had been content with question marks in the relevant positions in 1869 But aside from this, it is difficult to discern any qualitative difference between the two papers that might count as significant in this regard.7... 

The chemistry of superheavy elements has made some considerable progress in the last decade [457]. As the recently synthesized elements with nuclear charge 112 (eka-Hg), 114 (eka-Pb) and 118 (eka-Rn) are predicted to be chemically quite inert [458], experiments on these elements focus on adsorption studies on metal surfaces like gold [459]. DFT calculations predict that the equilibrium adsorption temperature for element 112 is predicted 100 °C below that of Hg, and the reactivity of element 112 is expected to be somewhere between those of Hg and Rn [460, 461]. This is somewhat in contradiction to recent experiments [459], and DFT may not be able to simulate accurately the physisorption of element 112 on gold. More accurate wavefunction based methods are needed to clarify this situation. Similar experiments are planned for element 114. 

Lars Frederik Nilson (1840-1899) found the element predicted by Dmitry Ivanovich Mendeleev (1834-1907) as "eka-boron" in the mineral gadolinite. 

The element "eka-cesium" had long been suspected. Was detected as a short-lived intermediate product in the decay series of actinium. 

The position on the periodic chart under lead would be filled by an element of atomic number 114. No such element is yet known, but scientists theorize that this would be a very stable element if it could be found or created, and it might have some very important uses. This much-sought element is referred to as i eka-lead, using the naming system Mendeleyev used for undiscovered elements in the original periodic chart. 

Gallium - the atomic number is 31 and the chemical symbol is Ga. The name derives from the Latin gallia for France or perhaps from the Latin gallus for le coq or cock , since it was discovered in zinc blende by the French chemist Paul-Emile Lecoq de Boisbaudan in 1875. It was first isolated in 1878 by Lecoq de Boisbaudran and the French chemist Emile-Clement Jungflesch. This element had previously been predicted as eka-aluminum by Mendeleev, along with its properties and its location in the Periodic Table. 

Scandium - the atomic number is 21 and the chemical symbol is Sc. The name derives from the Latin scandia for Scandinavia , where the mineral were found. It was discovered by the Swedish chemist Lars-Fredrik Nilson in 1879 from an ytterbium sample. In the same year, the Swedish chemist Per Theodore Cleve proved that scandium was Mendeleev s hypothetical element eka-boron , whose properties and position in the Period Table Mendeleev had previously predicted. 

The placement of an unknown element with an atomic number of 87 in group 1, period 7 of the periodic table was one of Dimitri Mendeleevs ideas based on the chemical properties and physical characteristics of the other alkali metals. In the late nineteenth century, Mendeleev named this unknown element eka-cesium and predicted its properties based on what was known of cesium s placement on the periodic table. This led to worldwide searches for element number 87, which were not all successful but which did result in proposed names for eka-cesium (moldavium, virginium, russium). 

GaUium is one of the elements Mendeleev predicted to fill the space just below aluminum. He named it eka-aluminum and even gave it the chemical symbol Ea because, when found, it would mostly resemble aluminum. He also suggested that it would combine with oxygen with the formula Ea O. ... 

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