43
Tc
Technetium
98
Technetium (Tc)
Transition MetalGroup 7Period 5d-block-blockRadioactive
Technetium (/tɛkˈniːʃiəm/) is a chemical element with symbol Tc and atomic number 43. It is the element with the lowest atomic number in the periodic table that has no stable isotopes:every form of it is radioactive. Nearly all technetium is produced synthetically, and only minute amounts are found in nature.
Latin name: Technetium
Atomic Number
43
Atomic Mass
98 g/mol
Phase (STP)
Solid
Electron Config.
[Kr] 4d⁵ 5s²
General
SymbolTc
Atomic Number43
Atomic Mass98 g/mol
CategoryTransition Metal
Group7
Period5
Blockd-block
Electron Configuration[Kr] 4d⁵ 5s²
Valence Electrons7
Colourshiny gray metallic
Appearanceshiny gray metal
CAS NumberCAS7440-26-8
Physical Properties
Phase (STP)Solid
Density11.5 g/cm³
Melting Point2156.85°C · 3914.33°F · 2430.00 K
Boiling Point4264.85°C · 7708.73°F · 4538.00 K
Atomic Properties
Atomic Radius183 pm
Electronegativity1.9 Pauling
Ionization Energy702 kJ/mol
Oxidation States+7, +6, +4
Ion ChargeTc4+/Tc7+
Thermodynamic
Molar Heat24.27 J/(mol·K)
Crystal Structure
Crystal Structurehexagonal close-packed
Mechanical Properties
Mohs Hardness5
Nuclear & Hazards
RadioactiveYes
Abundance
In Universe0.00000001%
In Sun0.00000001%
In Earth's Crust0.00000001%
Discovery & History
Discovery Year1937
Discovered ByCarlo Perrier, Emilio Segrè
Country of DiscoveryItaly
Isotopes of Technetium
| Isotope | Abundance | Half-life | Decay |
|---|---|---|---|
| Tc-97 | — | 4.21 × 10⁶ years | EC |
| Tc-98 | — | 4.2 × 10⁶ years | β⁻ |
| Tc-99 | — | 2.11 × 10⁵ years | β⁻ |
| Tc-99m | — | 6.007 hours | IT |