Niobium (Columbium)
Atomic Number: 41
Symbol: Nb (Cb)
Atomic Weight: 92.90638
Discovery: Charles Hatchet 1801 (England)
Electron Configuration: [Kr] 5s1 4d4
Word Origin: Greek mythology: Niobe, daughter of Tantalus, as niobium is often associated with tantalum. Formerly known as Columbium, from Columbia, America, the original source of niobium ore. Many metallurgists, metal societies, and commercial producers still use the name Columbium.
Isotopes: 18 isotopes of niobium are known.
Properties: Platinum-white with a bright metallic luster, although niobium takes on a bluish cast when exposed to air at room temperatures for a long time. Niobium is ductile, malleable, and highly resistant to corrosion. Niobium does not naturally occur in the free state; it is usually found with tantalum.
Uses: Niobium, like tantalum, can act as an electrolytic valve allowing alternating current to pass in only one direction through an electrolytic cell. Niobium is used in arc-welding rods for stabilized grades of stainless steel. It is also used in advanced air frame systems. Superconductive magnets are made with Nb-Zr wire, which retains superconductivity in strong magnetic fields. Niobium is used in lamp filaments and to make jewelry. It is capable of being colored by an electrolytic process.
Element Classification: Transition Metal
Density (g/cc): 8.57
Melting Point (K): 2741
Boiling Point (K): 5015
Appearance: shiny white, soft, ductile metal
Atomic Radius (pm): 146
Atomic Volume (cc/mol): 10.8
Covalent Radius (pm): 134
Ionic Radius: 69 (+5e)
Specific Heat (@20°C J/g mol): 0.268
Fusion Heat (kJ/mol): 26.8
Evaporation Heat (kJ/mol): 680
Debye Temperature (K): 275.00
Pauling Negativity Number: 1.6
First Ionizing Energy (kJ/mol): 663.6
Oxidation States: 5, 3
Lattice Structure: Body-Centered Cubic
Lattice Constant (Å): 3.300
References: Los Alamos National Laboratory (2001), Crescent Chemical Company (2001), Lange's Handbook of Chemistry (1952), CRC Handbook of Chemistry & Physics (18th Ed.)
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