Niobium
Niobium General
| Name:Niobium | Symbol:Nb |
| Type:Transition Metal | Atomic weight:92.9064 |
| Density @ 293 K:8.57 g/cm3 | Atomic volume:10.87 cm3/mol |
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Discovered:
Niobium was discovered in 1801 by Charles Hatchett in an ore sent to England more that a century earlier. Hatchett named the element columbium (symbol Cb). In 1846 Henrich Rose independently discovered the element and named it Niobium. The metal was first isolated by Christian Blomstrand in 1864. He reduced the chloride by heating it in a hydrogen atmosphere. The name niobium was adopted internationally in 1950. The element name comes from 'Niobe', meaning daughter of Tantalus in Greek mythology. |
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Niobium States
| State (s, l, g):solid | |
| Melting point:2750 K (2477 °C) | Boiling point:5017 K (4744 °C) |
Niobium Energies
| Specific heat capacity:0.26 J g-1 K-1 | Heat of atomization:733 kJ mol-1 |
| Heat of fusion:26.40 kJ mol-1 | Heat of vaporization :682.0 kJ mol-1 |
| 1st ionization energy:652.1 kJ mol-1 | 2nd ionization energy:1381.7 kJ mol-1 |
| 3rd ionization energy:2416 kJ mol-1 | Electron affinity:86.2 kJ mol-1 |
Niobium Oxidation & Electrons
| Shells:2,8,18,12,1 | Electron configuration: [Kr] 4d4 5s1 |
| Minimum oxidation number:-1 | Maximum oxidation number:5 |
| Min. common oxidation no.:0 | Max. common oxidation no.:5 |
| Electronegativity (Pauling Scale):1.6 | Polarizability volume:15.7 Å3 |
Niobium Appearance & Characteristics
| Structure:bcc: body-centered cubic | Color:silvery-white |
| Hardness:6.0 mohs | |
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Harmful effects:
Some niobium compounds are highly toxic. |
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Characteristics:
Niobium is a shiny, white, ductile metal. In air an oxide layer forms whose color depends on its thickness. Shades of blue, green and yellow are typical. Niobium resists corrosion due to the oxide film. The metal starts to oxidize rapidly in air at 200 oC. Niobium's chemical properties are very similar to those of tantalum. Niobium is one of the five major refractory metals (metals with very high resistance to heat and wear). The other refactory metals are tungsten, molybdenum, tantalum and rhenium. Uses: Niobium is used with iron and other elements in stainless steel alloys and also in alloys with a variety of nonferrous metals, such as zirconium, Niobium alloys are strong and are often used in pipeline construction. The metal is used in superalloys for jet engines and heat resistant equipment. Niobium is also used for jewelry. At cryogenic temperatures, niobium is a superconductor. |
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Niobium Reactions
| Reaction with air:w/ht, ⇒ NbO2 | Reaction with 6 M HCl:none |
| Reaction with 15 M HNO3:none | Reaction with 6 M NaOH: |
Niobium Compounds
| Oxide(s):NbO, NbO2, Nb2O3 , Nb2O5 | Chloride(s):NbCl3, NbCl4, NbCl5 |
| Hydride(s): NbH, NbH2 |
Niobium Radius
| Atomic radius:146 pm | Ionic radius (1+ ion):pm |
| Ionic radius (2+ ion):pm | Ionic radius (3+ ion):86 pm |
| Ionic radius (2- ion):pm | Ionic radius (1- ion):pm |
Niobium Conductivity
| Thermal conductivity:53.7 W m-1 K-1 | Electrical conductivity:6.6 x 106 S m-1 |
Niobium Abundance & Isotopes
| Abundance earth's crust:17 parts per million by weight, 3.7 parts per million by moles | |
| Abundance solar system:4 parts per billion by weight, 50 part per trillion by moles | |
| Cost, pure: $18 per 100g | |
| Cost, bulk:$ per 100g | |
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Source:
Niobium is not found free in nature but in minerals such as columbite and tantalite. Minerals that contain niobium often also contain tantalum. Commercially, niobium is extracted by first forming the oxide (Nb2O5). The oxide is then reduced using carbon or hydrogen. |
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Isotopes:
Niobium has 28 isotopes whose half-lives are known, with mass numbers from 83 to 110. Of these, one is stable, 93Nb. |
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Niobium Other
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Other:
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