43
97.91
Tc
Technetium
Identification
CAS Number: 7440-26-8
Discovery Year: 1937
Discoverer: Carlo Perrier, Émillo Segrè
Discovery Location: Italy
Properties
Atomic Dimensions
Atomic Radius: 135 pm →
Atomic Radius (Rahm): 252 pm
Covalent Radius: 147 pm →Van der Waals Radius: 216 pm
Metallic Radius: 127 pm
Atomic Volume: 8.5 cm³/mol
Lattice Constant: 2.74 Å
Thermodynamics
Electronic Structure
Electron Config: [Kr] 4d5 5s2
Block: d
Period: 5 →Group: 7 →Electronegativity: 2.1 →Electron Affinity: 0.55 eV →Oxidation States: +4, +6, +7
Abundance & Geochemistry
Goldschmidt Class: synthetic
About
Radioactive metallic transition element. Can be detected in some stars and the fission products of uranium. First made by Perrier and Segre by bombarding molybdenum with deutrons, giving them Tc-97. Tc-99 is the most stable isotope with a half-life of 2.6*10^6 years. Sixteen isotopes are known. Organic technetium compounds are used in bone imaging. Chemical properties are intermediate between rhenium and manganese.
Isotopes
Tc-97 97 ☢ 4.21e+6 a
Tc-98 98 ☢ 4.20e+6 s
Tc-99 99 ☢ 2.11e+5 a
