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| Atomic symbol: Tc |
| Atomic number: 43 |
| Atomic weight: 98.9062 |
| Atomic volume: 8.5 cm3/mol |
| Density: 11.5 g/cm3 |
| Period Number: 5 |
| Group number: 7 |
| Group name: Trans. Met. |
| Element classification: Metal |
| Phase at room temperature: Solid |
| Melting Point: 2445.2 K |
| Boiling point: 4840 K |
| Heat of fusion: 24.0 kJ/mol |
| Heat of vaporization: 660.0 kJ/mol |
| Ionization Energy: 7.28 eV |
| 1st ionization energy: 702.4 kJ/mole |
| 2nd ionization energy: 1472.4 kJ/mole |
| 3rd ionization energy: 2850.2 kJ/mole |
| Electronegativity: 1.9 |
| Electron affinity: 53 kJ/mole |
| Specific heat: 0.21 J/gK |
| Heat atomization: 677 kJ/mole atoms |
| Shells: 2,8,18,14,1 |
| Electron Shell Configuration: [Kr] 4d5 5s2 |
| Minimum oxidation number: -3 |
| Maximum oxidation number: 7 |
| Minimum common oxidation number: 0 |
| Maximum common oxidation no: 7 |
Appearance & Characteristics |
| Structure:: hcp: hexagonal close pkd |
| Color: silvery gray |
| Hardness: mohs |
| Toxicity: ? |
| Characteristics: Radioactive, man made |
| Uses: medical imaging agents |
| Reaction with air: mild, w/ht, =>Tc2O7 |
| Reaction with 6M HCl: none |
| Reaction with 15M HNO3: mild, =>HTcO4 |
| Reaction with 6M NaOH: ? |
| Number of isotopes: 0 |
| Oxide(s): TcO2 Tc2O7 |
| Hydride(s): none |
| Chloride(s): TcCl4 |
| Atomic Radius: 136 pm |
| Ionic radius (1- ion): pm |
| Ionic radius (1+ ion): pm |
| Ionic radius (2- ion): pm |
| Ionic radius (2+ ion): pm |
| Ionic radius (3+ ion): pm |
| Thermal conductivity: 50.6 J/m-sec-deg |
| Electrical conductivity: 1/mohm-cm |
| Polarizability: 11.4 A^3 |
| Source: Synthetic (U fission) |
| Relative abundance solar system: log |
| Abundance earth's crust: log |
| Estimated crustal abundance: Not Applicable |
| Estimated oceanic abundance: Not Applicable |
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| (Gr. technetos: artificial) Element 43 was predicted on the basis of the periodic table, and was erroneously reported as having been discovered in 1925, at which time it was named masurium. The element was actually discovered by Perrier and Segre in Italy in 1937. It was also found in a sample of molybdenum sent by E. Lawrence that was bombarded by deuterons in the Berkeley cyclotron. Technetium was the first element to be produced artificially. Since its discovery, searches for the element in terrestrial material have been made. Finally in 1962, technetium-99 was isolated and identified in African pitchblende (a uranium rich ore) in extremely minute quantities as a spontaneous fission product of uranium-238 by B.T. Kenna and P.K. Kuroda. If it does exist, the concentration must be very small. Technetium has been found in the spectrum of S-, M-, and N-type stars, and its presence in stellar matter is leading to new theories of the production of heavy elements in the stars. |
| Technetium is a silvery-gray metal that tarnishes slowly in moist air. The common oxidation states of technetium are +7, +5, and +4. Under oxidizing conditions technetium (VII) will exist as the pertechnetate ion, TcO4-. The chemistry of technetium is said to be similar to that of rhenium. Technetium dissolves in nitric acid, aqua regia, and concentrated sulfuric acid, but is not soluble in hydrochloric acid of any strength. The element is a remarkable corrosion inhibitor for steel. The metal is an excellent superconductor at 11K and below. |
| Twenty-two isotopes of technetium with masses ranging from 90 to 111 are reported. All the isotopes of technetium are radioactive. It is one of two elements with Z < 83 that have no stable isotopes; the other element is promethium (Z = 61). Technetium has three long lived radioactive isotopes: 97Tc (T1/2 =2.6 x 106 years), 98Tc (T1/2 = 4.2 x 106 years) and 99Tc (T1/2 = 2.1 x 105 years). 95Tcm ("m" stands for meta state) (T1/2 = 61 days) is used in tracer work. However, the most useful isotope of technetium is 99Tcm (T1/2 = 6.01 hours) is used in many medical radioactive isotope tests because of its half-life being short, the energy of the gamma ray it emits, and the ability of technetium to be chemically bound to many biologically active molecules. Because 99Tc is produced as a fission product from the fission of uranium in nuclear reactors, large quantities have been produced over the years. There are kilogram quantities of technetium currently existing. |
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