Niobium, this second element of group 5 and fifth of period 5 of block d belongs to the family of transition metals. Its electronic configuration is [Kr] 5s1 4d4 in order of increasing energy level6. It is the monoisotopic element 41, in the sense that there is only one stable natural isotopic variety. Its electronegativity is around 1.6.

By its melting point and its moderate density, the metal Nb approaches molybdenum.

The group V B, respectively comprises vanadium V23, niobium Nb41 and tantalum Ta73. The melting and boiling points of the simple bodies of this group are high, the enthalpies of vaporization significant. Vanadium differs significantly from niobium and tantalum, the first has an atomic radius of about 0.122 nm while the other two have a similar atomic radius, of about 0.134 nm, due to the lanthanum contraction. Thus the pentavalent compounds Nb (V) and even more Ta (V) are stable, like the "acidic earths" Nb2O5 or Ta2O5, acid-base bodies or amphoteric oxides, then the pentavalent vanadium compounds V (V) are clearly oxidizing. The vanadium metal V0 is much more reactive than Nb0 and especially Ta0, relatively inert.

Niobium belongs to the group of five refractory metals in the sense that their melting point is higher than that of platinum. The other four simple bodies are tantalum Ta, tungsten W, molybdenum Mo and rhenium Re.

Niobium and tantalum are often found together in nature. The two simple bodies are difficult to isolate and separate in their pure state.

The main producer of niobium is Brazil, at 80% of world production, while a single mine located in Saint-Honor¨¦, in Quebec, Canada, accounts for 15% of world production. But it remains the orogenic shield of New Quebec.

Niobium is also found in North Kivu in the Democratic Republic of the Congo, 20 but also in Gabon, China in Jiangxi and Russia, for example in the Irkutsk or Murmansk oblast, in the Kola peninsula in the mountains. from Lovozero. Niobium is also produced in Australia and Nigeria, India and South Africa. It is also mined in Malawi and Gabon. It can also be extracted from slag from Malaysian tin mines, where it is in the form of impurities.

Madagascar became a producer in 2008. In addition, there are large quantities of niobium in Afghanistan but the poor infrastructure in this country makes its exploitation very difficult21.


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