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Element Fact
In 1961, the International Union of Pure and Applied Chemistry adopted the isotope carbon-12 as the basis of atomic weight, which has a mass of exactly 12.000 atomic mass unit.

Niobium, Nb

niobium sample

Atomic number: 41
Atomic mass: 92.90638(2)
Natural abundance: 20 ppm
93Nb (92.90638) - 100%

History and Production

Derived from Greek Niobe, daughter of Tantalus. In 1801 C. Hatchett examined a mineral was has been sent to England from Massachusetts about fifty years earlier. He isolated the oxide of a new element which he named columbian and the corresponding mineral columbite, in honour of its country of origin. However, the element was confused with the other same member of element tantalum by A.G. Ekeberg in 1802 when he was examining some Finnish minerals. It was after more than 40 years when finally H. Rose examined a columbite sample and show that these elements were different. The metal niobium was first isolated in 1864 by Blomstrand by heating the chloride in a hydrogen atmosphere. The name niobium was adopted by the International Union of Pure and Applied Chemistry (IUPAC) in 1950 but there are still few other commercial producers in the US still refer to columbium. It can be extracted as a byproduct in the extraction of tin and subsequently isolated by using a solvent extraction technique, often from tantalum. The metal is used in arc-welding rods, as alloys for jet engine components and heat resistance equipment. It is also used in superconductor applications such as making superconducting magnets (made with Nb/Zr wires).

Physical Data

It is shiny, white metal and rather soft. It consists of about 20 ppm in crustal abundance which is frequently found together with tantalum such as in niobite (or columbite), (Fe,Mn)M2O6 (M = Nb,Ta).

Interatomic distance: 285.8 pm
Melting point: 2477C
Boiling point: 4744C
Thermal conductivity/Wm-1K-1: 53.7 (27C)
Density/kgm-3: 8570 (20C), 7830 (m.p.)

Standard Thermodynamic Data (atomic gas)

Enthalpy of formation: 725.9 kJ/mol
Gibbs free energy of formation: 681.1 kJ/mol
Entropy: 186.3 J/mol K
Heat capacity: 30.2 J/mol K

Electronic data

Electronic configuration: [Kr] 4d4 5s1
Term symbol: 6D1/2
Electron affinity: 86.1615 kJ/mol   Electronegativity (Pauline): 1.60
Ionization energy (first, second, third): 652.130, 1381.67, 2415.99 kJ/mol

Chemical properties

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