Element 43
Technetium (Tc)
Technetium (Tc) is element 43 of the periodic table, a transition metal in period 5, group 7 (d-block) with an atomic mass of 98 and is a solid at standard conditions.
At a glance
- Atomic number
- 43
- Symbol
- Tc
- Atomic mass
- 98 u
- Category
- Transition metals
- Period
- 5
- Group
- 7
- Block
- d-block
- Phase at STP
- solid
Electron structure
- Electron configuration
- 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d5 5s2
- Shorthand configuration
- [Kr] 4d5 5s2
- Electrons per shell
- 2, 8, 18, 13, 2
- Oxidation states
- -3, -1, +1, +2, +3, +4, +5, +6, +7
Physical properties
- Melting point
- 2430 K
- Boiling point
- 4538 K
- Density
- 11.5 g/cm3
- Phase
- solid
Atomic properties
- Electronegativity (Pauling)
- 1.9
- Atomic radius
- 183 pm
- Covalent radius
- 147 pm
- First ionization energy
- 702 kJ/mol
- Electron affinity
- 53 kJ/mol
Notable isotopes
| Isotope | Mass | Abundance | Stability |
|---|---|---|---|
| Tc-98 | 97.90722 | — | Half-life 4.2 million years |
Common uses
- Medical imaging
- Nuclear medicine
- Calibration sources
Discovery
- Year
- 1937
- Discovered by
- Carlo Perrier, Emilio Segrè
- Country
- Italy