technetium electron configuration
[23] Pure, metallic, single-crystal technetium becomes a type-II superconductor at temperatures below 7.46 K.[note 2][24] Below this temperature, technetium has a very high magnetic penetration depth, greater than any other element except niobium. The silvery gray, crystalline transition metal lies between manganese and ruthenium in group 7 of the periodic table, and its chemical properties are intermediate between those of both adjacent elements. Full and half-full subshells are the primary signs of a more stable electron configuration. Electron Configuration Chart for All Elements in the Periodic Table. [53], The primary decay mode for isotopes lighter than technetium-98 (98Tc) is electron capture, producing molybdenum (Z = 42). [90], As noted, the radioactive nature of technetium (3 MBq/L at the concentrations required) makes this corrosion protection impractical in almost all situations. That evidence bolstered the hypothesis that heavier elements are the product of nucleosynthesis in stars. TcCl4 is obtained by chlorination of Tc metal or Tc2O7 Upon heating, TcCl4 gives the corresponding Tc(III) and Tc(II) chlorides. It can also be extracted to a high chemical and isotopic purity from radioactive waste. The formation of ruthenium-106 (half-life 374 days) from the 'fresh fission' is likely to increase the activity of the final ruthenium metal, which will then require a longer cooling time after irradiation before the ruthenium can be used. [52][54], Technetium also has numerous nuclear isomers, which are isotopes with one or more excited nucleons. 0000039008 00000 n 0000074242 00000 n One theory holds that the pertechnetate reacts with the steel surface to form a layer of technetium dioxide which prevents further corrosion; the same effect explains how iron powder can be used to remove pertechnetate from water. [23] Other fissile isotopes produce similar yields of technetium, such as 4.9% from uranium-233 and 6.21% from plutonium-239. Electron Configuration: [Kr] 5s 2 4d 5 Word Origin: Greek technikos : an art or technetos : artificial; this was the first element made artificially. The ground state of the nuclide technetium-99 is used as a gamma-ray-free source of beta particles.

In 1947[16] element 43 was named after the Greek word τεχνητός, meaning "artificial", since it was the first element to be artificially produced. Each element has a unique atomic structure that is influenced by its electronic configuration, which is the distribution of electrons across different orbitals of an atom. Atomic technetium has characteristic emission lines at wavelengths of 363.3 nm, 403.1 nm, 426.2 nm, 429.7 nm, and 485.3 nm. [53] Technetium-99m emits only gamma rays and decays to technetium-99. 0000000730 00000 n In one experiment, a specimen of carbon steel was kept in an aqueous solution of pertechnetate for 20 years and was still uncorroded. [17] The soluble pertechnetate TcO−4 can then be chemically extracted by elution using a saline solution. For technetium-98 and heavier isotopes, the primary mode is beta emission (the emission of an electron or positron), producing ruthenium (Z = 44), with the exception that technetium-100 can decay both by beta emission and electron capture. 0000000879 00000 n [80][81][82], Technetium-99m ("m" indicates that this is a metastable nuclear isomer) is used in radioactive isotope medical tests. These clusters have the nuclearity Tc4, Tc6, Tc8, and Tc13. Technetium could be immobilized by some environments, such as microbial activity in lake bottom sediments,[71] and the environmental chemistry of technetium is an area of active research. Technetium also has numerous nuclear isomers, which are isotopes with one or more excited nucleons. [13], The discovery of element 43 was finally confirmed in a 1937 experiment at the University of Palermo in Sicily by Carlo Perrier and Emilio Segrè. As predicted by the periodic law, its chemical properties are between those two elements. Electron configuration of every element in the periodic table # Element Electron configuration 1 Hydrogen 1s1 2 Helium 1s2 3 Lithium 1s22s1 4 Beryllium 1s22s2 5 Boron 1s22s22p1 6 Carbon 1s 22s22p 7 Nitrogen 1s 22s 2p3 8 Oxygen 1s22s22p4 9 Fluorine 1s22s22p5 10 Neon 1s22s22p6 11 Sodium 1s22s22p63s1 12 Magnesium 1s22s22p63s2 13 Aluminum 1s 22s 2p63s 3p1 14 Silicon … [53], Technetium-99 (99Tc) is a major product of the fission of uranium-235 (235U), making it the most common and most readily available isotope of technetium. The two new Canadian Multipurpose Applied Physics Lattice Experiment reactors planned and built to produce 200% of the demand of technetium-99m relieved all other producers from building their own reactors. [10][11] Still, in 1933, a series of articles on the discovery of elements quoted the name masurium for element 43. [84], Technetium-99 decays almost entirely by beta decay, emitting beta particles with consistent low energies and no accompanying gamma rays.

0000011258 00000 n Unlike permanganate (MnO−4), it is only a weak oxidizing agent. However, small amounts exist as spontaneous fission products in uranium ores. Technetium, with atomic number Z = 43, is the lowest-numbered element in the periodic table for which all isotopes are radioactive. [41], Several anionic technetium halides are known. The most common naturally occurring isotope is 99Tc, in traces only. The common oxidation states of technetium are +7, +5, and +4. Isotopes: Twenty-one isotopes of technetium are known, with atomic masses ranging from 90-111. Lawrence mailed him a molybdenum foil that had been part of the deflector in the cyclotron. %PDF-1.4 %���� 8 0 obj <> endobj xref 8 13 0000000016 00000 n Of the two, technetium more closely resembles rhenium, particularly in its chemical inertness and tendency to form covalent bonds. Discovery: Carlo Perrier, Emilio Segre 1937 (Italy) found it in a sample of molybdenum that had been bombarded with neutrons; erroneously reported Noddack, Tacke, Berg 1924 as Masurium. She has taught science courses at the high school, college, and graduate levels. This pale-yellow, volatile solid is produced by oxidation of Tc metal and related precursors: It is a very rare example of a molecular metal oxide, other examples being OsO4 and RuO4. A drawback of this process is that it requires targets containing uranium-235, which are subject to the security precautions of fissile materials. For example, Technetium-99m is a radioactive tracer that medical imaging equipment tracks in the human body. (The other element is promethium.) From the 1860s through 1871, early forms of the periodic table proposed by Dmitri Mendeleev contained a gap between molybdenum (element 42) and ruthenium (element 44). The situation is similar for the related elements of Mo, W, Re. The binary tetrahalides can be converted to the hexahalides [TcX6]2− (X = F, Cl, Br, I), which adopt octahedral molecular geometry. [20], Since that discovery, there have been many searches in terrestrial materials for natural sources of technetium.

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They isolated the metastable isotope technetium-99m, which is now used in some ten million medical diagnostic procedures annually. The team claimed to detect a faint X-ray signal at a wavelength produced by element 43. [53] This is followed by technetium-95m (61 days, 0.03 MeV), and technetium-99m (6.01 hours, 0.142 MeV). [note 3], Technetium-99 is produced by the nuclear fission of both uranium-235 and plutonium-239. [23] The chemistry of technetium allows it to be bound to a variety of biochemical compounds, each of which determines how it is metabolized and deposited in the body, and this single isotope can be used for a multitude of diagnostic tests. [21] Technetium is produced in quantity by nuclear fission, and spreads more readily than many radionuclides. The liquid left after plutonium–uranium extraction (PUREX) contains a high concentration of technetium as TcO−4 but almost all of this is technetium-99, not technetium-99m.

[93], Coordination and organometallic complexes, Irregular crystals and trace impurities raise this transition temperature to 11.2 K for 99.9% pure technetium powder. One gram of technetium-99 produces 6.2×108 disintegrations per second (in other words, the specific activity of 99Tc is 0.62 GBq/g).[23]. It is isomorphous to transition metal tetrachlorides of zirconium, hafnium, and platinum. Technetium halides exhibit different structure types, such as molecular octahedral complexes, extended chains, layered sheets, and metal clusters arranged in a three-dimensional network. [51] Thirty other radioisotopes have been characterized with mass numbers ranging from 85 to 118. Technetium-97m (97mTc; "m" stands for metastability) is the most stable, with a half-life of 91 days and excitation energy 0.0965 MeV. [25], Technetium is located in the seventh group of the periodic table, between rhenium and manganese. [91] The radiological toxicity of technetium (per unit of mass) is a function of compound, type of radiation for the isotope in question, and the isotope's half-life. [40][41] These compounds are produced by combining the metal and halogen or by less direct reactions. [74], Molybdenum-99, which decays to form technetium-99m, can be formed by the neutron activation of molybdenum-98. Many early researchers, both before and after the periodic table was published, were eager to be the first to discover and name the missing element. [37] Similarly the dioxide can be produced by reduction of the Tc2O7. The chemistry of technetium is similar to that of rhenium. The fission of a gram of uranium-235 in nuclear reactors yields 27 mg of technetium-99, giving technetium a fission product yield of 6.1%. [22], The metal form is slightly paramagnetic, meaning its magnetic dipoles align with external magnetic fields, but will assume random orientations once the field is removed. [65], The vast majority of the technetium-99m used in medical work is produced by irradiating dedicated highly enriched uranium targets in a reactor, extracting molybdenum-99 from the targets in reprocessing facilities,[31] and recovering at the diagnostic center the technetium-99m produced upon decay of molybdenum-99.

[72], An alternative disposal method, transmutation, has been demonstrated at CERN for technetium-99. However, its radioactivity is a major problem in safe catalytic applications. Molybdenum-99 has a half-life of 67 hours, so short-lived technetium-99m (half-life: 6 hours), which results from its decay, is being constantly produced. [21][57] These red-giants are known informally as technetium stars.

[88] For this reason, pertechnetate has been used as an anodic corrosion inhibitor for steel, although technetium's radioactivity poses problems that limit this application to self-contained systems. Mendeleev gave it the provisional name ekamanganese (from eka-, the Sanskrit word for one) because the predicted element was one place down from the known element manganese.[5]. [85] Technetium-99 has also been proposed for optoelectronic devices and nanoscale nuclear batteries. [19] The stars were near the end of their lives but were rich in the short-lived element, which indicated that it was being produced in the stars by nuclear reactions. The potassium salt is isostructural with ReH2−9.[39]. [63][64][note 4]. In 1937, they succeeded in isolating the isotopes technetium-95m and technetium-97. Technetium fluoride (TcF 6) Technetium sulphide (TcS 2) Interesting facts: It was one of the elements that was predicted before it was discovered based upon the pattern discovered by Mendeleev. [66][67] Molybdenum-99 in the form of molybdate MoO2−4 is adsorbed onto acid alumina (Al2O3) in a shielded column chromatograph inside a technetium-99m generator ("technetium cow", also occasionally called a "molybdenum cow").


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