| Tecken | Tc |
| Atomnummer | 43 |
| Grupp | 7 (Mangangruppen) |
| Period | 5 |
| Block | d |
| Ämnesklass | Övergångsmetall |
| Utseende | Shiny gray metal |
| Färg | Silver |
| Antal protoner | 43 p+ |
| Antal neutroner | 55 n0 |
| Antal elektroner | 43 e- |
| Fas vid STP | Fast |
| Densitet | 11 g/cm3 |
| Relativ atommassa | 98.9062 u |
| Smältpunkt | 2430 K 2156.85 °C 3914.33 °F |
| Kokpunkt | 4538 K 4264.85 °C 7708.73 °F |
| Ångbildningsvärme | 502 kJ/mol |
| Elektronegativitet (Paulingskalan) | 1.9 |
| Elektronaffinitet | 53 kJ/mol |
| Oxidationstal | −3, −1, 0, +1, +2, +3, +4, +5, +6, +7 (a strongly acidic oxide) |
| Jonisationspotential |
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| Förutsägelse | Dmitri Mendeleev (1871) |
| Upptäckt och första isolation | Carlo Perrier, Emilio Segrè (1937) |
Upptäckten av teknetium From the 1860s through 1871, early forms of the periodic table proposed by Dmitri Mendeleev contained a gap between molybdenum (element 42) and ruthenium (element 44). In 1871, Mendeleev predicted this missing element would occupy the empty place below manganese and have similar chemical properties. The discovery of element 43 was finally confirmed in a 1937 experiment at the University of Palermo in Sicily by Carlo Perrier and Emilio Segrè. Segrè enlisted his colleague Perrier to attempt to prove, through comparative chemistry, that the molybdenum activity was indeed from an element with the atomic number 43. In 1937, they succeeded in isolating the isotopes technetium-95m and technetium-97. University of Palermo officials wanted them to name their discovery "panormium", after the Latin name for Palermo, Panormus. In 1947 element 43 was named after the Greek word τεχνητός, meaning "artificial", since it was the first element to be artificially produced. | |