Technetium

tecnecio

Technetium was the first element produced artificially by researchers. It is named after the Greek word for artificial, tekhnetos. Technetium does not exist in nature: any of its atoms that once existed on Earth decayed millions of years ago. Small amounts of this element were discovered in the waste produced by early nuclear reactors. Technetium is the lightest radioactive element. It is widely used in medical imaging. It is injected into a patient's body, where it emits radiation for a short time. Some machines use this radiation to show bones clearly.

Chemical properties

Very little is known about the chemistry of technetium. At least three oxides are known: TcO2, in the "+4" oxidation state is black; TcO3, in the oxidation state "+6" is purple; and Tc2O7, in the "+7" oxidation state is yellow. As it is in VIIA group, thus, its "+7" oxidation state is the preferred one.

In addition, the pertechnetate ion (TcO-4) also exhibits "+7" oxidation state. It is readily reduced by copper metal to metallic technetium, as indicated in the following reaction which takes place in acidic solution:

2TcO4(aq) + 7Cu(s) + 16H+(aq) → 2Tc(s) + 7Cu2+(aq) + 8H2O(l)

Technetium forms halides. TeCl4 is deep red, TeCl6 is green and TeF6 is yellow.

Resumen de propiedades (Tc)

Atomic weight[97]
Discoverer (year)Perrier, Carlo & Segrè, Emilio (1937)
Natural formmetallic solid (hexagonal)
Electron configuration[Kr] 4d5 5s2
Melting point (ºC)2200
Boiling point (ºC)4877
Abundance in earth's crust (ppm)synthetic
Isotope (abundance)
Density g/cm311.5
Van der Waals radius (pm)216
Covalent radius (pm)138
Electronegativity (Pauling)1.9
Vaporization enthalpy (kJ/mol)585.00
Enthalpy of fusion (kJ/mol)33.29
Specific heat capacity (J/g·K) at 25ºC and 1 atm-
Thermal conductivity (W/cm·K) at 25ºC and 1 atm0.510
Oxidation state+7, +6, +4
Electron affinity (eV)0.55
1st Ionization potential (eV)7.2800

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