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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magnesium bismuth manganese chromium cobalt titanium
Tungsten vanadium niobium indium molybdenum antimony
rhenium germanium zirconium cadmium hafnium
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