Technetium (Tc)
Transition metal · d-block · period 5 · group 7
Silvery-grey radioactive metal (only ever seen in tiny amounts).
Technetium (symbol Tc) is chemical element number 43, a transition metal in group 7, period 5 of the periodic table. Its standard atomic weight is (98) and its electron configuration is [Kr] 4d5 5s2. At room temperature it is a solid, and it is radioactive. The first element to be made artificially — its name means 'artificial'.
Properties
| Atomic number | 43 |
|---|---|
| Atomic mass | (98) |
| Category | Transition metal |
| Block | d-block |
| Group · Period | 7 · 5 |
| Electron configuration | [Kr] 4d5 5s2 |
| Electrons per shell | 2, 8, 18, 13, 2 |
| State at 25 °C | solid |
| Melting point | 2430 K |
| Boiling point | 4538 K |
| Density | 11 g/cm³ |
| Electronegativity (Pauling) | 1.9 |
| Radioactive | Yes — no stable isotope |
| Origin | synthetic |
| Discovered | 1937 · Perrier & Segrè |
Key facts about Technetium
- The first element to be made artificially — its name means 'artificial'.
- There is a gap at atomic number 43 in nature because it has no stable isotope.
- Technetium-99m is the workhorse tracer of medical imaging, used in tens of millions of scans a year.
- Traces exist in uranium ores from spontaneous fission.
What Technetium is used for
Medical diagnostic imaging (bone, heart, thyroid scans), corrosion-inhibitor research.
Where it sits in the periodic table
Technetium is in group 7, period 5, of the d-block. Its electron configuration [Kr] 4d5 5s2 means its outermost shell holds 2 electrons, which is what places it here and explains much of its chemistry. See Technetium on the interactive table →
Technetium — frequently asked questions
What is Technetium used for?
Medical diagnostic imaging (bone, heart, thyroid scans), corrosion-inhibitor research.
Is Technetium radioactive?
Yes. Technetium has no stable isotope, so every form of it is radioactive.
What is the electron configuration of Technetium?
Technetium has the electron configuration [Kr] 4d5 5s2, which is 2, 8, 18, 13, 2 electrons per shell.
What group and period is Technetium in?
Technetium is in group 7, period 5, in the d-block. Its outer shell holds 2 electrons.
Who discovered Technetium?
Technetium was discovered in 1937 by Perrier & Segrè.