Technetium's existence was first predicted by Dmitri Mendeleev. Technetium was officially discovered by Carlo Perrier and Emilio Segrč in 1936 in an experiment at the University of Palermo in Sicily.
Name: Technetium
Symbol: Tc
Atomic number: 43
Atomic weight: 97.91
State: solid
Group, period, block: 7, 5, d
Color: shiny gray metal
Classification: transition metal
Electron configuration: 4d5 5s2
2,8,18,12,2
Physical properties
Density: 11 g/cm-3
Melting point: 2430 K,2157 °C,3915 °F
Boiling point: 4538 K,4265 °C,7709 °F
Atomic properties
Oxidation states: 7, 6, 5, 4, 3[1], 2, 1[2], -1, -3
Electronegativity: 1.9 (Pauling scale)
Ionization energies: 1st: 702 kJ·mol-1
Covalent radius: 147±7 pm
Van der Waals radius: no data
- Tc
Electron Configuration
Isotopes
All isotopes of technetium are radioactive. The most stable radioactive isotopes are 98Tc with a half-life of 4.2 million years (Ma), 97Tc (half-life: 2.6 Ma) and 99Tc (half-life: 211,000 years).