Symbol	Nb
Atomic number	41
Group	5 (Vanadium group)
Period	5
Block	d
Classification	Transition Metal

Appearance	Gray metallic, bluish when oxidized
Color	Gray

Number of protons	41 p+
Number of neutrons	52 n0
Number of electrons	41 e-

From Wikipedia, the free encyclopediaNiobium, formerly columbium, is a chemical element with symbol Nb (formerly Cb) and atomic number 41. It is a soft, grey, ductile transition metal, which is often found in the pyrochlore mineral, the main commercial source for niobium, and columbite. The name comes from Greek mythology:Niobe, daughter of Tantalus since it is so similar to tantalum.

Phase at STP	Solid
Density	8.57 g/cm3
Atomic weight	92.9064 u

Melting point	2750 K 2476.85 °C 4490.33 °F
Boiling point	5017 K 4743.85 °C 8570.93 °F
Heat of vaporization	690.1 kJ/mol

Electronegativity (Pauling Scale)	1.6
Electron affinity	88.516 kJ/mol
Oxidation states	−3, −1, 0, +1, +2, +3, +4, +5 (a mildly acidic oxide)
Ionization energies	652.1 kJ/mol 1380 kJ/mol 2416 kJ/mol 3700 kJ/mol 4877 kJ/mol 9847 kJ/mol 12100 kJ/mol

Electron configuration Shorthand configuration	[Kr] 4d4 5s1
Electron configuration Full configuration	1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d4 5s1
Electron configuration chart	1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d4 5s1
Electrons per shell	2, 8, 18, 12, 1
Valence electrons	5
Valency electrons	3,5
Bohr model	Figure: Shell diagram of Niobium (Nb) atom.
Orbital Diagram	1s 2s 2p 3s 3p 3d 4s 4p 4d 5s

Discovery	Charles Hatchett (1801)
First isolation	Christian Wilhelm Blomstrand (1864)
Recognized as a distinct element by	Heinrich Rose (1844)
Discovery of niobium Niobium was identified by English chemist Charles Hatchett in 1801. He found a new element in a mineral sample that had been sent to England from Connecticut, United States in 1734 by John Winthrop F.R.S. (grandson of John Winthrop the Younger) and named the mineral columbite and the new element columbium after Columbia, the poetic name for the United States. In 1809, English chemist William Hyde Wollaston wrongly concluded that tantalum and columbium were identical. German chemist Heinrich Rose determined in 1846 that tantalum ores contain a second element, which he named niobium. In 1864 and 1865, a series of scientific findings clarified that niobium and columbium were the same element (as distinguished from tantalum), and for a century both names were used interchangeably. Niobium was officially adopted as the name of the element in 1949, but the name columbium remains in current use in metallurgy in the United States.

CAS Number	7440-03-1
ChemSpider ID	22378
EC number	231-113-5
PubChem CID Number	23936