Eka boron

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... 

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)... 

Mendeleev predicted that eka-boron sulphate is less soluble than aluminium sulphate. This is not the case. 

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

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. 

Mendeleev observed that there were some gaps in his table, empty spaces to which no element was assigned. He concluded that these represented elements that had not yet been discovered. For example, there was a gap under boron, so Mendeleev concluded that it must be an unknown element with properties like boron. He named it eka-boron ( eka is Sanskrit for the numeral one). Similarly, there were gaps under aluminum and silicon. Mendeleev called these missing elements eka-aluminum and eka-silicon. The positions of the missing elements in his table allowed him to estimate their atomic weights and also to describe their chemical and physical properties accurately. 

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. 

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. ... 

Mendeleev had determined some physical and chemical properties of elements before they were discovered and gave these unknown elements names such as eka-aluminum, eka-silicon, eka-boron, eka-cesium and eka-iodine. 

Ans. Mendeleev had used the prefix eka- (Sanskrit word for first) to name elements whose existence he predicted, applying the prefix to a known element in the same periodic group as the predicted element. His eka-boron, eka-aluminum, and e a-silicon were later discovered, confirmed, and named scandium, gallium, and germanium. Elements 104 and 105 were predicted to have electronic structures analogous to Hf and Ta. 

Two years later the world was completely convinced. Out of Scandinavia came the report that Nilson had isolated eka-boron. Picking up the scent of the missing element in the ore of euxenite, Nilson had tracked it down until the naked element, exhibiting every property foreshadowed for it, lay before him in his evaporating dish The data were conclusive. The whole world of science came knocking at the door of the Russian in St. Petersburg. 

Here in Group III was a gap between calcium and titanium. Since it occurred under boron, the missing element must resemble boron. This was his eka-boron which he predicted. There was another gap in the same group under aluminum. This element must resemble aluminum, so he called it eka-aluminum. And finally he found another vacant space between arsenic and eka-aluminum, which appeared in the fourth group. Since its position was below the element silicon, he called it eka-silicon. Thus he predicted three undiscovered elements and left it to his chemical contemporaries to verify his prophecies. Not such remarkable guesses after all—at least not to the genius Mendel eff ... 

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-... 

Before the element scandium was discovered in 1879, it was known as eka-boron. Predict the properties of scandium from averages of the corresponding properties of its neighboring elements in the periodic table. Compare your predictions with the observed values in Appendix F. 

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. 

The name is derived from the Latin Scandia, the name of Scandinavia. Mendeleev predicted the existence of the element as eka-boron. It was discovered by Lars Fredrick Nilson (1840-1899) in 1878 when he was investigating trace elements in euxenite and gadolinite. Metallic scandium was first prepared in 1937. Spectroscopic analysis has shown that scandium is present in the sun and other stars. Blue beryl may be colored because of scandium. The silvery metallic element is used in high-intensity lighting. 

MiniLab 1 Mendeleev predicted the existence of eka-boron, which was unknown in his day. Eka-boron was located between calcium and titanium on the periodic table. What is the name of eka-boron now ... 

Since he expected the three elements to have properties similar to those of boron, aluminum, and silicon, respectively, he tentatively named them eka-boron, eka-aluminum, and eka-silicon. 

Eka-boron was discovered in 1879 by Lars F. Nilson of Sweden. He named it scandium, for Scandinavia. 

The true insight that informed Mendeleev s work was shown not just in what he had included in the Periodic Table, but also in what he had left out. He did not assume that all elements were known. Where there was a significant gap in atomic weights between the elements in the table, he left a gap in the table. He posited that there were undiscovered elements that existed in the gaps and even predicted the characteristics of three of them. He called these eka boron, eka aluminum, and eka silicon eka being Sanskrit for first ). See Tables 1 through 3 for the properties of these elements. 

Table 2. Eka boron was predicted by Mendeleev and discovered by the Swedish physicist Lars Fredrik Nilson in 1879 and named scandium.

The most famous of Mendeleev s predictions involved eka-boron (scandium), eka-aluminium (gallium), and eka-silicon (germanium). For example, for eka-silicon he predicted its atomic weight, its density, the compounds it would form, and details about their physical properties. When thirteen years later germanium was discovered and it was determined that Mendeleev s predictions had been correct, scientists began to recognize the importance of the Periodic Table, and its discovery was quite naturally associated with Mendeleev, who encouraged this association. 

Even so there remained three important gaps in the fourth and. fifth rows of the table. Mendel eff again took his courage in both hands and suggested that these pointed to the existence of three elements as yet unknown to science. He named them eka-boron, -aluminium and -silicon respectively moreover he went so far Is to indicate the general properties these elements would be found to possess when discovered. 

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