Manganese atomic weight

Manganese [7439-96-5] atomic number 25, atomic weight 54.94, belongs to Group 7 (VII) ia the Periodic Table. Its isotopes are Mn, Mn, Mn,... 

Moissan 3 in 1880 called attention to the fact that the affinities of chromium, manganese, iron, cobalt, and nickel for oxygen and the heats of formation of oxides, chlorides, bromides, iodides, and sulphides decrease as the atomic weights rise. 

Just as silicon in the first group shows similarities with titanium on the one hand and with germanium on the other, there exists in exactly the same way a relationship between the elements of the 2nd and 3rd groups, for example from zirconium to cerium with an atomic weight of 140 on the one hand and from zirconium to an unknown element with an atomic weight aroimd 181 on the other. There are a large number of rare-earth elements in between these two elements which are related to one another like the central elements of the 3rd series placed between manganese and zinc. (Thomsen, 1895 Trifonov, 1966). 

Important new insights into the various ways in which the elements could be interrelated were gained during the middle decades of the nineteenth century. The German chemist Leopold Gmelin (1788-1853) pointed out in 1843 that whereas in some triads the atomic weights hardly differed at all, for example, in chromium-manganese-iron, in other triads... 

If manganous sulphate, MnSO, yields 42.392 per cent of oxygen, what is the atomic weight of manganese ... 

If the region between helium and uranium contains 91 elements then five are as yet undiscovered. These have been predicted and named (1) eka-manganese with an atomic number 43 and an atomic weight approximately 100 (2) dwi-manganese, atomic number 75 falling between tungsten and osmium (3) eka-iodine, atomic number 85 (4) eka-neodym-ium, a rare earth element of atomic number 61 and (5) eka-caesium of atomic number 87. Of these, greatest interest has... 

VV is actually very nearly a linear function of the atomic number by atomic number is understood the number expressing the position of an atom in the series order of the periodic system (1 H, 2 He, 3 Li. . . ), thus practically in the order of the atomic weights the gaps required by chemistry (e.g. that of the element 43 homologous to manganese) are to be taken into account as well as the reversals required by chemical behaviour [e.g. ] 8 A (at. wt. 39-88), and 19 K (39-10)]. 

In 1869 Mendeleev 1 predicted the existence of an clement of atomic weight ]()() occupying the vacant space between molybdenum and ruthenium in his Periodic System. He named this element provisionally ekamanganese" corresponding to its position below manganese. In 1913 and 1914 Moseley 2,3] found the atomic number of elements in the Periodic System to be directly proportional to the square root of the frequency of their K ox L X-ray emission and thus derived a vacant space for the atomic number 43 in addition to 61 (Pm) and 75(Re). These indications of Mendeleev and Moseley stimulated numerous attempts to demonstrate the occurrence of element 43 [4..S] and the other elements lacking in nature. 

Such are nickel and cobalt, whose atomic weights are very close to each other, ihodium, ruthenium and palladium on the rate hand, iridium, osmium and platinum on the other ate also elements which closely resemble one another, and which have very similar atomic weights. Iron and manganese have similar properties and their atomic weights are also very similar ... 

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