Mendeleev predictions

L. Scandia, Scandinavia) On the basis of the Periodic System, Mendeleev predicted the existence of ekaboron, which would have an atomic weight between 40 of calcium and 48 of htanium. 

Latin Germania, Germany) Mendeleev predicted the existence of Germanium in 1871 as ekasilicon, and the element was discovered by Winkler in 1886. 

What is not well known is that about half of the elements that Mendeleev predicted were never found. But given the dramatic success of his early predictions these later lapses have largely been forgotten. 

Keywords Mendeleev Prediction Periodic Table Weight of Evidence,... 

Mendeleev predicted that the melting point of gallium would fall between those of aluminium (660°C) and indium (115°C). In fact gallium has an anomalously low melting point of 30°C. 

Mendeleev predicted that salts of germanium are less stable than those of aluminium. In fact aluminium salts are the more readily hydrolysed. 

Mendeleev predicted that scandium would be precipitated by hydrogen sulphide. This is not the case. 

Mendeleev predicted that eka-silicon is a refractory substance as predicted by Mendeleev. In fact it melts at the relatively low temperature of 950°C.16... 

On the other hand, if one considers all of Mandeleev s many predictions of new elements, his powers of prophecy appear somewhiit less impressive, even to the point of being a little worrying. In all Mendeleev predicted a total of 16 elements, of which only nine were subsequently Isolated. As one historian of chemistry has wondered, how b it that weareprcpaied to forgive Mendeleev so many failures ... 

Mendeleev was bolder in his interpretation than Lothar Meyer, and for this reason we honor him as the primary discoverer of the modem periodic table. A few elements did not fit the pattern of variation in combining numbers with molar mass. Mendeleev proposed that these irregularities meant that the element s molar mass had been measured incorrectly. For example, Mendeleev predicted that the correct molar mass of indium is 113 g /mol, not 75 g /mol, the value assigned at that time on the assumption that the formula for indium oxide is InO. Later experiments showed that the correct formula is L12 O3, and indium s tme molar mass is 114.8 g/mol. 

Although germanium was unknown, Mendeleev predicted the properties of the missing element (which he referred to as ekasilicon) based on the properties of other elements. While analyzing the mineral argyrodite, Winkler found that it contained about 7% of some element that had not been identified, 463... 

Even though hafnium is not a scarce or rare element, it was not discovered until 1923 because of its close association with zirconium. Several scientists suspected that another element was mixed with zirconium but could not determine how to separate the two because zirconium ore contains about 50 times more zirconium than hafnium. Mendeleev predicted that there was an element with the atomic number of 72, but he predicted it would be found in titanium ore, not zirconium ore. 

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. ... 

In 1871 Dmitri Mendeleev predicted the existence of a new element that would have similar properties as silicon. He called this yet to be found element eka-silicon, which he assigned the symbol Es with an atomic weight of 72 and a specific gravity of 5.5. 

VV hen Mendeleev predicted that occupants would be found for the vacant spaces in the periodic system, he little dreamed that three of them would be discovered during his lifetime. 

After titanium was discovered in 1791 by the Reverend William Gregor in Cornwall, its atomic weight was determined by such able chemists as H. Rose, C. G. Mosander, and J.-B.-A. Dumas, but the results showed such great discrepancies that Mendeleev predicted that another element would be found in titanium ores (17). 

As a scientific idea, Mendeleev s periodic table was tested by making predictions about elements that were unknown at that time but could possibly fill the gaps. Three of these gaps are shown by the symbols and J in Figure 9.2. As new elements were discovered, they were found to fit easily into the classification. For example, Mendeleev predicted the properties of the missing element eka-silicon (f). 

In 1886 the element we now know as germanium was discovered in Germany by Clemens Winkler its properties were almost exactiy those Mendeleev had predicted. In all, Mendeleev predicted the atomic weight of ten new elements, of which seven were eventually discovered - the other three, atomic weights 45, 146 and 175, do not exist ... 

In 1870 Dimitri Mendeleev predicted many of the properties of an unknown element that he called eka-aluminum. The element was discovered in 1875... 

An inspection of Table 1 impresses one by the precise way in which Mendeleev predicted the properties of germanium and its elementary derivatives. 

In 1966, Rochow27 somewhat criticized the accuracy of Mendeleev s predictions of the properties of eca-silicon (germanium). He stated Mendeleev predicted that mt-silicon would decompose steam with difficulty, whereas germanium does not decompose it at... 

In 1869, Mendeleev predicted the existence and certain properties of an element with atomic mass 45, terming it ekaboron within a decade, the Swede L. F. Nilsson and Frenchman P. T. Cleve independently isolated scandium oxide, subsequently preparing various other compounds. There are few ores where scandium is the main element (e.g. thortveitite, a silicate, Sc2Si207, and sterrite, SCPO4 2H2O) so that it is mainly obtained as a by-product from uranium extraction. 

Although Mendeleev predicted the existence of several undiscovered elements, he did not predict the existence of the noble gases, the lanthanides, or the actinides. Propose reasons why Mendeleev was not able to predict the existence of the noble gases. 

The existence of germanium was predicted by Russian chemist Dmitri Mendeleev (1834—1907), who developed the periodic table. Mendeleev predicted a new element would be found to fill an empty spot on the table. He was proved correct in 1886. 

Mendeleev made a prediction that the empty places in the periodic table stood for elements that had not yet been discovered. He said one could tell what those elements were going to be like by examining their position in the periodic table. For example, element number 21 would be like boron, Mendeleev predicted. Boron was the element above number 21 in Mendeleev s chart. He called the missing element (number 21) ekaboron, or similar to boron. ... 

Mendeleev predicted the existence of Ge, eka-silicon, before its discovery. 

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