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The vanadium subgroup is the VB group in the periodic table, including three elements: vanadium (V), vanadium (Nb), but (Ta)
.
The valence electron layer configuration of vanadium and butan atoms is (n-1)d 3 ns 2 , and the valence electron layer configuration of niobium atoms is 4d 4 5s 1 , and the most stable oxidation state is +5
The mass fraction of vanadium in the earth's crust is 1.
6×10 -2 % (ranking 19th).
The most important mineral of vanadium is chlorsulfovanadium VS4.
Other minerals include vanadinite Pb 5 (VO 4 ) 3 Cl and vanadium.
Potash ore K 2 (UO 2 ) 2 (VO 4 ) 2 ·3H 2 O, etc.
, but there are few rich ore
.
Vanadium is extremely dispersed in nature, so it is a rare element
Elementary substance of vanadium subgroup elements
1.
Refinement of simple substance
The niobium subgroup element has high reactivity at high temperature, and it is difficult to extract
.
Vanadium is mostly extracted from the residues of other metal smelting.
The vanadium minerals or vanadium-rich residues are calcined with NaCl or Na 2 CO 3 to convert vanadium into NaVO 3 , and the leaching solution is adjusted to pH=2~3 to obtain rich V 2 The "red cake" of O 5 is calcined at 700°C to obtain V 2 O 5
.
Reduce V 2 O 5 to obtain industrial grade metallic vanadium
Vanadium may be utilized to extract high purity metal Na or H 2 reduction of VCl .
3 , elemental Mg reducing the VCI .
4 is obtained
.
All vanadium subgroup metals can be prepared by electrolytic melting of fluorine coordination compounds
2.
The nature of the element
The vanadium subgroup elements are silver-white with metallic luster.
High-purity metals are softer and have good ductility.
When they contain impurities, they become hard and brittle
.
The vanadium subgroup elements are all active metals
.
However, due to the surface passivation, the activity is low at room temperature
The vanadium subgroup element does not react with air, water, or alkali at room temperature.
Vanadium reacts with HNO 3 , concentrated H 2 SO 4 and aqua regia.
Among non-oxidizing acids, it only reacts with HF
.
2V+6HF=2VF 3 +3H 2
From the element potential diagram of vanadium below, it can be seen that HNO 3 can oxidize vanadium to +4 oxidation state
.
At high temperatures, the simple substance of vanadium subgroup elements can react with many non-metals, and can interact with molten caustic alkali, such as
Metal vanadium is mainly used to make alloy steel.
A small amount of vanadium is added to the steel to significantly improve the hardness and elasticity of the steel.
It can be used to make springs and high-speed tools
Niobium has good corrosion resistance, cold workability and strong thermal conductivity, and is often used to produce alloy steel
.
Niobium-zirconium alloy can be used as a superconducting magnet
Niobium and tantalum are extremely inactive and do not interact with other acids except HF
.
Related Links: Compounds of Titanium Subgroup Elements