Technetium Facts - Periodic Table of the Elements

Technetium (Masurium)Â   Atomic Number: 43 Symbol: Tc Atomic Weight: 98.9072 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. Electron Configuration: [Kr] 5s2 4d5 Word Origin: Greek technikos: an art or technetos: artificial; this was the first element made artificially. Isotopes: Twenty-one isotopes of technetium are known, with atomic masses ranging from 90-111. Technetium is one of two elements with Z 83 with no stable isotopes; all of technetiums isotopes are radioactive. (The other element is promethium.) Some isotopes are produced as uranium fission products. Properties: Technetium is a silvery-gray metal that tarnishes slowly in moist air. Common oxidation states are 7, 5, and 4. The chemistry of technetium is similar to that of rhenium. Technetium is a corrosion inhibitor for steel and is an excellent superconductor at 11K and below. Uses: Technetium-99 is used in many medical radioactive isotope tests. Mild carbon steels may be effectively protected by minute quantities of technetium, but this corrosion protection is limited to closed systems because of technetiums radioactivity. Element Classification: Transition Metal Technetium Physical Data Density (g/cc): 11.5 Melting Point (K): 2445 Boiling Point (K): 5150 Appearance: silvery-gray metal Atomic Radius (pm): 136 Covalent Radius (pm): 127 Ionic Radius: 56 (7e) Atomic Volume (cc/mol): 8.5 Specific Heat (20Â °C J/g mol): 0.243 Fusion Heat (kJ/mol): 23.8 Evaporation Heat (kJ/mol): 585 Pauling Negativity Number: 1.9 First Ionizing Energy (kJ/mol): 702.2 Oxidation States: 7 Lattice Structure: Hexagonal Lattice Constant (Ã…): 2.740 Lattice C/A Ratio: 1.604Â   Sources: CRC Handbook of Chemistry Physics (18th Ed.)Crescent Chemical Company (2001)Langes Handbook of Chemistry (1952)Los Alamos National Laboratory (2001)