Description
The name niobium was adopted by IUPAC in 1950, but a few commercial producers still refer to it as Columbium.Niobium is a shiny, white, soft, and ductile metal, and takes on a bluish cast when exposed to air at room temperatures for a long time. The metal starts to oxidise in air at elevated temperatures, and when processed at even moderate temperatures must be placed in a protective atmosphere.
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General information
Discoveror: Charles Hatchett
Date discovered: 1801
Discovered at: England
Meaning of name: From the Greek word "Niobe" meaning "daughter of Tantalus" (tantalum is closely related to niobium in the periodic table)
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Physical data
Standard state: solid at 298 K
Colour: grey metallic
Density of solid at ambient temperature/kg m-3: 8570
Molar volume/cm3: 10.83
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Radii /pm
Atomic: 198
Covalent (single bond):
Pauling radius for the ion [Nb]-: no data
Valence shell orbital radius maxima (Rmax)
| orbital |
s |
p |
d |
f |
| radius | 181.9 | no data | 78.9 | no data |
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Electronegativities
Both values are quoted on the Pauling scale.
Pauling: 1.6
Allred Rochow: 1.23
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Crystal Structure
structure: bcc (body-centred cubic)
The following CrystalMaker image represents the solid state structure. For most elements, the most stable allotrope is illustrated. Try WebElements version 2 for interactive virtual reality and CHIME images.
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Temperatures (/K)
melting point: 2750
boiling point: 5017
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Enthalpies /kJ mol-1
fusion: 26.9
vaporization: 690
single bond enthalpies:
| Nb-F |
Nb-Cl |
Nb-Br |
Nb-I |
Nb-Nb |
| no data |
no data |
no data |
no data |
511 |
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Ionization enthalpies /kJ mol-1
| Number |
Enthalpy |
| 1st | 664 |
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| 2nd | 1382 |
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| 3rd | 2416 |
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| 4th | 3695 |
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| 5th | 4877 |
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| 6th | 9900 |
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| 7th | 12100 |
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Isotopes
This section gives some data for naturally occurring isotopes.
| Nominal mass |
Accurate mass |
% natural abundance |
| 93Nb | 92.9063772 (27) | 100 |
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Further Information
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