Niobium (41)

The name niobium was adopted officially by IUPAC in 1950, but a few commercial producers still like to refer to it as columbium. Niobium is a shiny, white, soft, and ductile metal, and takes on a bluish tinge when exposed to air at room temperatures for a long time. The metal starts to oxidize in air at high temperatures, and when handled hot must be done so under a protective atmosphere so as to minimize oxide production.

•Name: Niobium
•Symbol: Nb
•Atomic number: 41
•Atomic weight: 92.90638 (2)
•Standard state: solid at 298 K
•CAS Registry ID: 7440-03-1
•Group in periodic table: 5
•Period in periodic table: 5
•Block in periodic table: d-block
•Color: grey metallic
•Classification: Metallic

Historical information

Niobium was discovered by Charles Hatchett at 1801 in England. Origin of name: from the Greek word "Niobe" meaning "daughter of Tantalus" (tantalum is closely related to niobium in the periodic table). Niobium was discovered in 1801 by Charles Hatchett in an ore called columbite sent to England in the 1750s by John Winthrop the Younger, the first governor of Connecticut, USA. Hatchett called the new element columbium. He was not able to isolate the free element. There was then considerable confusion concerning the distinction between niobium and tantalum as they are so closely related. This confusion was resolved by Heinrich Rose, who named niobium, and Marignac in 1846. The name niobium is now used in place of the original name "columbium".

The metal niobium was first prepared in 1864 by Blomstrand, who reduced the chloride by heating it in a hydrogen atmosphere.

Physical properties

•Melting point: 2750 [or 2477 °C (4491 °F)] K
•Boiling point: 5017 [or 4744 °C (8571 °F)] K
•Density of solid: 8570 kg m-3

Orbital properties

•Ground state electron configuration: [Kr].4d4.5s1
•Shell structure: 2.8.18.12.1
•Term symbol: 6D1/2

 

Isolation

Isolation of niobium appears to be complicated. Niobium minerals usually contain both niobium and tantalum. Since they are so similar chemically, it is difficult to separate them. Niobium can be extracted from the ores by first fusing the ore with alkali, and then extracting the resultant mixture into hydrofluoric acid, HF. Current methodology involves the separation of tantalum from these acid solutions using a liquid-liquid extraction technique. In this process tantalum salts are extracted into the ketone MIBK (methyl isobutyl ketone, 4-methyl pentan-2-one). The niobium remains in the HF solution. Acidification of the HF solution followed by further extraction in MIBK gives an organic solution containing niobium.