|Name: technetium||Group number: 7|
|Symbol: Tc||Group name: (none)|
|Atomic number: 43||Period number: 5|
|Atomic weight: [ 98 ]||Block: d-block|
|CAS Registry ID: 7440-26-8||Voice: |
|Standard state: solid at 298 K||Colour: silvery grey metallic|
|Classification: Metallic||Availability: |
There is a thin plating of technetium-99 on this disk and this radioactive sample gives about 200 counts per minute. Image adapted with permission from Prof James Marshall"s (U. North Texas, USA) Walking Tour of the elements CD.
Since its discovery, searches for the element technetium in terrestrial materials have been made without success. Technetium has been found in the spectrum of S-, M-, and N-type stars, and its presence in stellar matter is leading to new theories of the production of heavy elements in the stars.
Technetium is a silvery-grey metal that tarnishes slowly in moist air. Until 1960, technetium was available only in small amounts. The chemistry of technetium is related to that of rhenium.
IsolationHere is a brief summary of the isolation of technetium.
It is never necessary to make a sample of techntium anywhere other than specialist laboratories. This is because technetium is radioactive. Technetium is a byproduct of the nuclear industry and is a product of uranium decay. Alternatively it can be made by the bombardment of molydenum targets with deuterium nuclei.
Because of the scale of the nuclear industry it is possible to make quite large quantities of technetium (kilograms). The metal itself may be made by the reaction of the sulphide Tc2S7 with hydrogen at 1100°C or of the pertechnate NH4TcO4 with hydrogen.