Tc
Technetium
Element 43 · Transition metal
Technetium (Tc)
Technetium is a radioactive silvery metal and the lightest element with no stable isotopes. It is a workhorse of medical imaging.
- Transition metal
- Period 5
- Group 7
- d-block
- solid at room temperature
- ☢ Radioactive
Key properties
- Atomic mass
- [97]
- u
- Electron configuration
- [Kr] 4d5 5s2
- Melting point
- 2,156.9 °C
- 2,430 K
- Boiling point
- 4,264.9 °C
- 4,538 K
- Density
- 11 g/cm³
- Electronegativity
- 1.9
- Pauling
- Atomic radius
- 209 pm
- van der Waals
- 1st ionisation energy
- 7.28 eV
Compare with every element:Electronegativity chartAtomic radius chartIonisation energy chartDensity chart of the elementsMelting point chartElectron configuration chart
Did you know?
Notable facts about technetium
- 01
It was made from molybdenum foil that had been bombarded in a cyclotron at Berkeley.
- 02
Technetium-99m is used in tens of millions of medical scans every year.
- 03
Some red giant stars show technetium in their spectra, proving that stars make new elements.
Applications
What is technetium used for?
- Medical diagnostic imaging (Tc-99m)
- Corrosion inhibitor research
- Calibration sources
History
Discovery & name origin
Discovered by
Year
Where
Italy
Name origin
Greek technetos, “artificial” — the first element made artificially.
Atomic structure
Atomic properties
Atomic structure
Atomic properties
- Atomic number
- 43
- Atomic mass
- [97] u
- Group
- 7
- Period
- 5
- Block
- d-block
- Electron configuration
- [Kr] 4d5 5s2
- Full configuration
- 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d5
- Electrons per shell
- 2, 8, 18, 13, 2
- Electronegativity (Pauling)
- 1.9
- Electron affinity
- 0.55 eV
- Atomic radius (van der Waals)
- 209 pm
- Stable isotopes
- None — all isotopes are radioactive
Oxidation states
Highlighted: common oxidation states (+7, +6, +4).
Successive ionisation energies
Energy to remove each electron in turn (kJ/mol). Big jumps show where a new, inner shell begins.
- 1st702
- 2nd1,470
- 3rd2,850
Physical
Physical properties & colour
Physical
Physical properties & colour
- State at 20 °C
- Solid
- Melting point
- 2,430 K · 2,156.9 °C · 3,914.3 °F
- Boiling point
- 4,538 K · 4,264.9 °C · 7,708.7 °F
- Density
- 11 g/cm³
- Molar heat capacity
- 24.27 J/(mol·K)
- Appearance
- Shiny grey metal
- CPK model colour
- Copied
The CPK colour is the convention used for this element’s atoms in molecular models.
FAQ
Technetium questions
What is Tc on the periodic table?
Tc is the symbol for technetium, element 43 on the periodic table. It sits in group 7, period 5, in the transition metal category, and has an atomic mass of [97].
What is the atomic number of technetium?
Technetium has atomic number 43, so every technetium atom has 43 protons in its nucleus. Its symbol is Tc and its atomic mass is [97].
Who discovered technetium?
Technetium was discovered by Emilio Segrè and Carlo Perrier in 1937 (Italy). The name comes from Greek technetos, “artificial” — the first element made artificially.
What is technetium used for?
Technetium is used for: medical diagnostic imaging (Tc-99m); corrosion inhibitor research; calibration sources.
Is technetium a metal?
Yes. Technetium is a transition metal, one of the metallic elements.
What is the electron configuration of technetium?
The electron configuration of technetium is [Kr] 4d5 5s2. Its 43 electrons are arranged in shells as 2, 8, 18, 13, 2.