Technetium atomic properties

The long-wavelength IR spectra of trigonal prismatic technetium clusters and a number of unusual physico-chemical properties of the clusters with ferrieinium cations [108] support the latter assumption. The discovered properties of the clusters with ferrieinium cations may be accounted for by the formation of the conductivity bands and, probably, hard-fermion bands in these compounds by the 5s(5p)-AO s of technetium atoms and 4s(4p)-AO s of the iron atoms. The formation of these bands may be supported by the following facts the ESR spectra of these compounds with geft close to that of a free electron temperature independent conductivity and an unusual temperature dependence of the Mossbauer and X-ray photoelectron spectra [108]. 

HOMO-LUMO. This may be supported by low Zeff of technetium atoms in tetragonal-prismatic clusters [103,127] and formation of compounds with fer-ricinium cations with some unusual physico-chemical properties, as is the case of trigonal-prismatic clusters [108,128]. 

Technetium, with an atomic number of 43, was discovered after Mendeleev s death. Nevertheless, he used the properties of manganese, rhenium, molybdenum, and ruthenium to predict technetium s properties. 

Physical Properties. Molybdenum has many unique properties, leading to its importance as a refractory metal (see Refractories). Molybdenum, atomic no. 42, is in Group 6 (VIB) of the Periodic Table between chromium and tungsten vertically and niobium and technetium horizontally. It has a silvery gray appearance. The most stable valence states are +6, +4, and 0 lower, less stable valence states are +5, +3, and +2. 

Some of the important properties of Group 7 elements are summarized in Table 24.1. Technetium is an artificial element, so its atomic weight depends on which isotope has been produced. The atomic weights of Mn and Re, however, are known with considerable accuracy. In the case of... 

Like rhenium and ruthenium it crystallizes in a closest packed hexagonal lattice with the metal atoms having the coordination number 12. In Table 2 some properties of technetium are compared with those of manganese and rhenium. 

As the central member of the triad of metals in group 7, technetium (period 5) has similar physical and chemical properties as its partners manganese (period 4) above it and rhenium (period 6) below it. The sizes of their atomic radii do not vary greatly Mn = 127, Tc = 136, and Re = 137. Neither does their level of electronegativity vary significantly Mn = 1.5, Tc =... 

Technetium is one of the few artificially produced elements that has practical industrial applications. One is that a very small amount (55-ppm) added to iron creates a corrosion-resistant alloy metal. This property is shared with many of the other transition metallic elements, but not with other artificially produced elements that have higher atomic numbers and are radioactive. 

Blau M, Wicks R, Thomas SR, Lathrop KA (1982) MIRD dose estimate report no. 10. Radiation absorbed dose from albumin microspheres labelled with technetium-99m. J Nucl Med 23 915-917 Bolles TF, Kubiatowicz DO, Evans RL, Grotenhuis IM, Nora JC (1973) Tc-99m-labelled albumin (human) microspheres (15-30 micron). Their preparation, properties and uses. In Radiopharmaceuticals and labelled compounds, vol. 1. International Atomic Energy Agency, Vienna, p 151-167 Council of Europe (1992) Guide for the preparation, use and quality assurance of blood components. Strasbourg... 

The elements will be discussed in the order of increasing atomic number in the Periodic Table, i.e. nickel, zinc, technetium, ruthenium, silver, hafnium, tantalum, tungsten, rhem um, osmium, iridium, platinum, gold, and mercury. Full numerical data of the relevant nuclear properties are summarized, as for other elements, in Appendix 1. 

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