The search for technetium in nature

Abstract

A historical account of element 43 is presented in this paper in four main phases: (a) the many searches and claims prior to its actual discovery in 1937; (6) its discovery and the preparation and identification of its isotopes; (c) its discovery in stars, and the theories to explain its presence there; and (d) the recent searches for naturally occurring terrestrial technetium. The chemistry of technetium is not treated here since it is more than adequately discussed by Anders (1) and Boyd (2).In his periodic table, Mendeleev (3, 4) left certain gaps and predicted that new elements would be discovered in time to fill these gaps. The atomic weights and physical, and chemical properties also were forseen.Two of these "missing" elements were congeners of manganese, which we know today as technetium and rhenium, elements 43 and 75. Because thenproperties would seem to be similar to manganese, he named them tentatively eka-manganese and dwi-manganese (sometimes written dvi-manganese), with the symbols Em and Dm. Their atomic weights were predicted to be 100 and 190, respectively. Further predictions were that their compounds would be colored and there would be a series of oxides corresponding to the oxides of manganese.The periodic table has provided a blueprint which indicated how many elements were possible up to the heaviest natural element, uranium. By about the middle of the third decade of this century, all 92 elements had been discovered, with the exceptions of elements 43, 61, 85, and 87. Even these found their way into the periodic table under various names.However, these "discoveries" were erroneous and, in the 1930's, it could be shown that these elements are all radioactive, having such short half-lives that their existence in appreciable amounts on the earth is not possible (5).Early Attempts To IsolatePolinium: The first recorded claim of finding a new element which would correspond to element 43 was in 1828.Osann, (6) while studying platinum ores, claimed three new elements, among which was one he named polinium. However, he later reported that polinium was actually impure iridium (7).Ilmenium: While examining various minerals, Hermann (8), in 1846, found what was thought to be a newThis paper is based on a portion of the dissertation submitted by the author to the Graduate School of the University of Arkansas in partial fulfillment of the requirements for the degree of Doctor of Philosophy.

Technetium: The First Radioelement on the Periodic Table

“…Of these hypothesized elements, Mendeleev predicted the discoveries of gallium, scandium, and germanium originally denoted as eka -aluminum, eka -boron, and eka -silicon, where the prefix eka means “first” in Sanskrit and refers to their chemical similarities and chronological arrangement. Along with these initially predicted elements was eka -manganese with an atomic weight of 100, which filled the gap underneath manganese and was also expected to have similar chemical properties. − …”

Interactions of Tc(IV) with citrate in NaCl media

“…Tc is present in the environment, mainly as a result of anthropogenic activities, from the disposal of nuclear materials [1][2][3] and nuclear weapon fall out [4]; a small fraction of 99 Tc found in nature is also naturally occurring due to 238 U spontaneous fission [5][6][7]. This isotope represents a significant environmental contaminant because of its halflife of 2.1 × 10 5 y, complex chemistry, and potential high mobility.…”

International Year of the Periodic Table 2019: Elements Important for Life Sciences

“…Technetium went through pelopium in 1847, davyum in 1877, lucium in 1897 and moseleyum in 1924, one year before rhenium was actually discovered. [6] Most of these discoveries turned out to be impure group 4 or 5 oxides or some other mixtures. The name moseleyum was only a proposal for the case that element 43 would be discovered since the investigation by X-ray spectroscopy of different uranium and thorium ores did not reveal any trace of the missing element.…”