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Tantalum is the chemical element with atomic number 73, symbol Ta.
The simple tantalum body is a gray-blue10 transition metal, heavy, hard but
ductile, very resistant to acid corrosion, and a good conductor of heat and
electricity. It is found in the mineral called tantalite and in some complex
ores in the form of oxide, associated with niobium, in particular in coltan, of
black color.
Tantalum is used for the manufacture of surgical instruments and implants
because it does not react with bodily fluids. It is very well known in
electronics for the manufacture of so-called ¡°tantalum drop¡± capacitors, so
named because of their easily recognizable shape and which have the largest
capacity per unit of volume.
This element has a high melting point which is only exceeded by osmium,
tungsten, carbon and rhenium (melting point at 3,016.85 ¡ã C, boiling point
5,457.85 ¡ã C) .
Its name is borrowed12 from modern scientific Latin tantalum12, a name given to
it in 1802 by the Swedish chemist Anders Gustaf Ekeberg by allusion to the
insoluble nature of this metal in acids
Tantalum and niobium (ex-columbium) were initially taken for the same element.
In 1801, a new metal was discovered by the English chemist Charles Hatchett
(1765-1847) by analyzing a black mineral from the collection of the governor of
Connecticut, then called Columbia. He baptized it Colombium, a name which will
not remain because of later work.
In 1802, Anders Gustaf Ekeberg (1767-1813) professor at the University of
Uppsala (Sweden) worked on an oxide very difficult to dissolve and to work. He
obtained what he took for a pure element and named it tantalum, named after the
Greek demigod (T¨¢ntalos), well known for his torture.
In 1809, William Hyde Wollaston after re-examining the columbium ore and
tantalite declared that the two new elements were in fact only one.
In 1820, tantalum was isolated by Jöns Jacob Berzelius.
In 1844, Heinrich Rose distinguished in tantalite two elements, tantalum,
certainly, but also a "new" which he baptized niobium, named Niobe the daughter
of Tantalus in Greek mythology.
It was quickly shown that columbium and niobium were only one element. A quarrel
of experts ensued over the name to be used and it was "niobium" which prevailed.
At the beginning of 1900, tantalum found its first application as an
incandescent filament for bulbs until the arrival of tungsten. In 1940, tantalum
began to be used to make capacitors. Two years later, the first colombo-tantalite
mining in the Belgian Congo (future Democratic Republic of the Congo) was born.
Geology and mineralogy
Tantalum ore (tantalite) from Australia.
The proportion of tantalum is estimated at around 1 or 2 ppm16 of the mass of
the earth's crust. It is mainly found in hydrothermal veins which are areas
where the elements present in the water can mineralize by encountering an
important source of heat, such as a pocket of magma. These places are more
easily present in geologically unstable places, close to tectonic fault and
volcanic region.
These veins are often very rich in heavy metals such as gold, silver, uranium,
cobalt, tungsten and of course tantalum and niobium. Subsequently, by erosion,
the elements can be washed away and end up in a watercourse where the heaviest
substances are deposited in places of weak current, such as meanders or pots.
Sometimes these areas heavy in heavy elements can form veins and find themselves
buried. One can thus find colombo-tantalite as well in metamorphic rocks as
sedimentary.
Tantalum forms very few specific minerals, and is noticeable in proportion only
in relatively few other minerals. The main mineral is coltan (or
columbotantalite), an association in variable proportions of columbite and
tantalite, two minerals themselves of variable composition. The term tantalite
covers the continuous series between tantalite- (Fe) and tantalite- (Mn), of
generic composition (Fe, Mn) Ta2O6. Among the specific minerals, mention may be
made of tantalcarbide, a carbide with a TaC composition.
Isotopes
Main article: Tantalum isotopes.
Tantalum has 36 known isotopes, with mass numbers varying between 155 and 188,
as well as 37 nuclear isomers. Among these isotopes, only one is stable: 181Ta,
and, one thing unique, a nuclear isomer: 180mTa, is also. The latter is in
principle a metastable state, but no disintegration having ever been observed,
it is currently considered stable. 181Ta (99.998%) and 180mTa (0.012%) represent
all of the naturally occurring tantalum. It is assigned a standard atomic mass
of 180.947 88 (2).
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rhenium germanium zirconium cadmium hafnium
barium lithium beryllium strontium calcium
Tantalum gadolinium samarium yttrium ytterbium
Lutetium praseodymium holmium erbium thulium dysprosium
terbium europium lanthanum cerium neodymium scandium
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