Tc

Technetium

Identification

CAS Number: 7440-26-8

Discovery Year: 1937

Discoverer: Carlo Perrier, Émillo Segrè

Discovery Location: Italy

Properties

Atomic Mass: 97.90721 →Density: 11 g/cm³ →

Crystal Structure: HEX

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

Melting Point: 2445 K →Boiling Point: 5150 K →Specific Heat: 0.243 J/(g·K) →Thermal Conductivity: 50.6 W/(m·K) →Heat of Fusion: 23.8 kJ/mol →Heat of Vaporization: 585 kJ/mol →

Heat of Formation: 678 kJ/mol

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