4398TcTechnetium
Technetium (Tc) — element 43transition metal · group 7, period 5
Technetium is a chemical element with the symbol Tc and atomic number 43. It is a transition metal in group 7, period 5 of the periodic table (the d-block), with a standard atomic mass of 98 u. At room temperature (25 °C) technetium is a solid.
💡 Known for: The first artificially produced element; technetium-99m is the most widely used medical imaging isotope.
# Technetium properties
| Symbol | Tc |
|---|---|
| Atomic number | 43 |
| Atomic mass | 98 u |
| Category | transition metal |
| Group | 7 |
| Period | 5 |
| Block | d-block |
| Electron configuration | [Kr] 4d⁵ 5s² |
| Full configuration | 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d⁵ 5s² |
| Electrons per shell | 2, 8, 18, 13, 2 |
| Protons / electrons | 43 / 43 |
| State at 25 °C | solid |
| Melting point | 2430 K (2156.8 °C, 3914.3 °F) |
| Boiling point | 4538 K (4264.9 °C, 7708.7 °F) |
| Density | 11.5 g/cm³ |
| Electronegativity (Pauling) | 1.9 |
| First ionization energy | 7.28 eV |
| Atomic radius | 183 pm |
| Discovered | 1937 |
# Electron configuration of technetium
The electron configuration of technetium is [Kr] 4d⁵ 5s², written out in full as 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d⁵ 5s². Its 43 electrons fill 5 shells as 2, 8, 18, 13, 2, so the outermost shell holds 2 electrons.
# Related elements
MoMolybdenumprevious elementRuRutheniumnext elementMnManganesegroup 7ReRheniumgroup 7BhBohriumgroup 7ScScandiumtransition metalTiTitaniumtransition metalVVanadiumtransition metalCrChromiumtransition metalFeIrontransition metalCoCobalttransition metalNiNickeltransition metalCuCoppertransition metal
# Technetium FAQ
What is the atomic number of technetium?
The atomic number of technetium is 43: every technetium atom has 43 protons in its nucleus. Its symbol is Tc.
What is the atomic mass of technetium?
The standard atomic mass of technetium is 98 u.
What is the electron configuration of technetium?
Technetium's electron configuration is [Kr] 4d⁵ 5s² (1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d⁵ 5s²), with 2, 8, 18, 13, 2 electrons per shell.
Is technetium a metal?
Yes. Technetium is a transition metal, one of the metals.
What is the melting point of technetium?
Technetium melts at 2430 K (2156.8 °C, 3914.3 °F) and boils at 4538 K (4264.9 °C, 7708.7 °F).
What is technetium used for / known for?
The first artificially produced element; technetium-99m is the most widely used medical imaging isotope.