About

Technetium is the lightest element whose isotopes are all radioactive, meaning it has no stable form. It was the first element to be produced artificially, hence its name. Its metastable isotope, technetium-99m, is the most widely used radioactive tracer in medical diagnostic procedures like bone and heart scans, due to its short half-life and clear gamma ray emission.

Atomic Properties

Atomic Number43

Atomic Weight98 u

Neutrons (common)55

Electron Configuration[Kr] 4d⁵ 5s²

Full Configuration1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d⁵ 5s²

Electrons per Shell2, 8, 18, 13, 2

Electronegativity1.9

Electron Affinity53 kJ/mol

Oxidation States+7, +6, +5, +4, -1

Covalent Radius156 pm

Ionic Radius56 pm

Periodic Table Position

Group7

Period5

BlockD

Chemical SeriesTransition metals

Physical Properties

State at STPsolid

Appearancesilvery-grey metallic

Crystal Structurehcp

Magnetic Orderingparamagnetic

Thermal Properties

Melting Point2,430 K

Boiling Point4,538 K

Thermal Expansion0 1/K

Thermal Conductivity50.6 W/(m·K)

Specific Heat0.243 J/(g·K)

Molar Heat23.8 J/(mol·K)

Heat of Fusion23.81 kJ/mol

Heat of Vaporization550 kJ/mol

Abundance

In Earth's Crust0 ppm

Discovery

Discovered byEmilio Segrè, Carlo Perrier

Discovery Year1,937

Occurrencesynthetic

CAS Number7440-26-8

Electron Configuration

Energy

↿⇂

↿

Isotopes of Technetium

Symbol ▲	Mass (u) ▲	Abundance ▲	Half-life ▲	Decay Mode ▲
⁹³Tc	92.910249	—	2.75 h	Positron Emission, Electron Capture
⁹⁴Tc	93.909657	—	4.883 h	Positron Emission, Electron Capture
⁹⁵Tc	94.907657	—	20.0 h	Electron Capture
⁹⁵Tc	95.907657	—	61.96 d	Internal Transition
⁹⁶Tc	95.907598	—	4.28 d	Electron Capture
⁹⁷Tc	96.906365	—	4.21 My	Electron Capture
⁹⁸Tc	97.907210	—	4.2 My	Beta Minus Decay
⁹⁹Tc	98.906254	Trace	211.1 ky	Beta Minus Decay
⁹⁹Tc	99.906254	—	6.0066 h	Internal Transition, Beta Minus Decay

Interactive Visualization

Explore the 3D Bohr model of Technetium in our interactive viewer.

View 3D Model of Technetium