Technetium
The lightest element with no stable isotopes, used in imaging.
Inside the Technetium atom
Switch between Bohr and Quantum Cloud modes to compare a simple teaching model with a more realistic probability-based view, and follow the guided tour to explore the Technetium atom step by step.
Electron configuration
[Kr] 4d5 5s2
A neutral Technetium atom has 43 electrons (equal to its proton count). Choosing a different isotope above changes only the neutron count.
Shell distribution
Electrons fill inner shells before outer ones; the outermost (valence) shell drives the element's chemistry.
Physical & atomic properties
- State (room temp)
- Solid
- Melting point
- 2430 K (2157 °C)
- Boiling point
- 4538 K (4265 °C)
- Density
- 11.5 g/cm³
- Electronegativity
- 1.9 Pauling
- Atomic radius
- 135 pm
- 1st ionization energy
- 702 kJ/mol
- Category
- Transition metals
Discovery & naming
- Discovered
- 1937
- Discovered by
- Carlo Perrier and Emilio Segrè
- Origin of name
- Greek 'technetos', meaning artificial.
Notable uses
Medical imaging tracers in nuclear scans.
Where Technetium comes from
Human synthesis
Has no stable isotope. Natural traces exist in uranium ores, but essentially all of it in use is made artificially.
Simplified origin map — many elements form through more than one astrophysical pathway.
Summary
- Atomic number
- 43
- Atomic mass
- [98]
- Category
- Transition metals
- Group · Period
- 7 · 5
- Block
- d-block
- Shells
- 2 · 8 · 18 · 13 · 2