Periodic table / Transition metals
43Technetium
Technetium is a transition metal in group 7, period 5. At 25 °C it is a solid.
- Symbol
- Tc
- Atomic number
- 43 protons in the nucleus
- Standard atomic weight
- None. Technetium has no stable isotopes, so the mass of a sample depends on which isotopes it holds.
- Electron configuration
- [Kr] 4d5 5s2
- Electrons in each shell
- 2, 8, 18, 13, 2
- Group, period, block
- 7, 5, d
- Family
- Transition metals
- State at 25 °C
- solid
- Electronegativity
- 1.9 (Pauling scale)
- First ionisation energy
- 686.9 kJ/mol (7.11938 eV)
Where these numbers come from
Atomic weight: IUPAC CIAAW, abridged standard atomic weights 2024. Electron configuration and ionisation energy: NIST Atomic Spectra Database. Family, state and electronegativity: PubChem. See Sources. Melting points, boiling points and densities are left out for now: published values differ between sources, and we will add them once each has been checked.