The Element Niobium
[Click for Isotope Data]
Atomic Number: 41
Atomic Weight: 92.90638
Melting Point: 2750 K (2477°C or 4491°F)
Boiling Point: 5017 K (4744°C or 8571°F)
Density: 8.57 grams per cubic centimeter
Phase at Room Temperature: Solid
Element Classification: Metal
Period Number: 5 Group Number: 5 Group Name: none
What's in a name? Named for the Greek mythological figure Niobe.
Say what? Niobium is pronounced as ni-OH-bee-um.
History and Uses:
The story of niobium's discovery is a bit confusing. The first governor of Connecticut, John Winthrop the Younger, discovered a new mineral around 1734. He named the mineral columbite ((Fe, Mn, Mg)(Nb, Ta)2O6) and sent a sample of it to the British Museum in London, England. The columbite sat in the museum's mineral collection for years until it was analyzed by Charles Hatchett in 1801. Hatchett could tell that there was an unknown element in the columbite, but he was not able to isolate it. He named the new element columbium.
The fate of columbium took a drastic turn in 1809 when William Hyde Wollaston, an English chemist and physicist, compared the minerals columbite and tantalite ((Fe, Mn)(Ta, Nb)2O6) and declared that columbium was actually the element tantalum. This confusion arose because tantalum and niobium are similar metals, are always found together and are very difficult to isolate.
Niobium was rediscovered and renamed by Heinrich Rose in 1844 when he produced two new acids, niobic acid and pelopic acid, from samples of columbite and tantalite. These acids are very similar to each other and it took another twenty-two years and a Swiss chemist named Jean Charles Galissard de Marignac to prove that these were two distinct chemicals produced from two different elements. Metallic niobium was finally isolated by the Swedish chemist Christian Wilhelm Blomstrand in 1864. Today, niobium is primarily obtained from the minerals columbite and pyrochlore ((Ca, Na)2Nb2O6(O, OH, F)).
Niobium is used as an alloying agent and for jewelry, but perhaps its most interesting applications are in the field of superconductivity. Superconductive wire can be made from an alloy of niobium and titanium which can then be used to make superconductive magnets. Other alloys of niobium, such as those with tin and aluminum, are superconductive as well. Pure niobium is itself a superconductor when it is cooled below 9.25 K (-442.75°F). Superconductive niobium cavities are at the heart of a machine built at the Thomas Jefferson National Accelerator Facility. This machine, called an electron accelerator, is used by scientists to study the quark structure of matter. The accelerator's 338 niobium cavities are bathed in liquid helium and accelerate electrons to nearly the speed of light.
Estimated Crustal Abundance: 2.0×101 milligrams per kilogram
Estimated Oceanic Abundance: 1×10-5 milligrams per liter
Number of Stable Isotopes: 1 (View all isotope data)
Ionization Energy: 6.759 eV
Oxidation States: +5, +3
3s2 3p6 3d10
4s2 4p6 4d4