Niobium - Nb General Information Discovery Niobium was discovered by C. Hatchett in 1801 in London, in an ore sent to England more than a century before by J. Winthrop, first Governor of Connecticut. Appearance Niobium is shiny, white, soft and ductile, and takes on a bluish sheen when exposed to air for a long time. Source The main source of this element is in the mineral columbite, which can be found in Canada, Brazil, the former USSR, Nigeria and elsewhere. However, it is commercially prepared as a by-product of tin extraction. Uses Niobium is used as an alloying agent in carbon and alloy steels and in non-ferrous metals, as it improves the strength of the alloy. It is also used in jet engines and rockets. This element has superconductive properties and is used in superconductive magnets which retain their properties in strong magnetic fields. This type of application could be used for the large-scale generation of electricity. Biological Role Niobium has no known biological role. General Information The name niobium was adopted officially in 1950 after years of controversy. The alternative name was columbium, and some metallurgists still use this name. Niobium resists corrosion due to an oxide film. It can be attacked by hot, concentrated acids but resists attack by fused alkalis. It starts to oxidise in air at 200K, and when processed at even moderate temperatures must be placed in a protective atmosphere.

	Physical Information
	Atomic Number		41
	Relative Atomic Mass (12C=12.000)		92.906
	Melting Point/K		2741
	Boiling Point/K		5015
	Density/kg m-3		8570 (293K)
	Ground State Electron Configuration		[Kr]4d45s1
	Electron Affinity(M-M-)/kJ mol-1		-109

	Key Isotopes
	nuclide	93Nb	94Nb
	atomic mass	92.91	93.91
	natural abundance	100%	0%
	half-life	stable	2x104 yrs

Other Information
Enthalpy of Fusion/kJ mol-1		27.2
Enthalpy of Vaporisation/kJ mol-1		680.19
Oxidation States
main	Nb+5
others	Nb-3, Nb-1, Nb+1, Nb+2,
	Nb+3, Nb+4

	Ionisation Energies/kJ mol-1
	M - M+	664
	M+ - M2+	1382
	M2+ - M3+	2416
	M3+ - M4+	3695
	M4+ - M5+	4877
	M5+ - M6+	9899
	M6+ - M7+	12100
	M7+ - M8+
	M8+ - M9+
	M9+ - M10+