Niobium Facts – Element Nb or Atomic Number 41


Niobium Facts
Niobium is the element with atomic number 41 and element symbol Nb.

Niobium is a transition metal that is known for its strength and unique physical properties. It has the atomic symbol Nb and atomic number 41. However, the element’s original name was columbium with symbol Cb.

Discovery and Naming

Niobium was discovered by the English chemist Charles Hatchett in 1801. He found it in a mineral sample from Connecticut. Hatchett named the new element columbium after the poetic name for America: Columbia. After Hatchett’s discovery, the element was known as columbium in the United States.

However, in 1844, the German chemist Heinrich Rose discovered two new elements in tantalite and named them niobium and pelopium. The name “niobium” comes from Greek mythology. Niobe was the daughter of Tantalus. The name reflects niobium’s similarities to the element tantalum. But, it became apparent that columbium and niobium were the same element.

In 1864, Christian Wilhelm Blomstrand became the first person to isolate the pure element.

In 1950, the International Unition of Pure and Applied Chemistry (IUPAC) made a compromise regarding element names. Element 41 became niobium (the European name), while element 74 became tungsten (the American name, over the European name of wolfram). Even so, the names columbium and wolfram persisted into the 20th century.

Physical Properties and Appearance

Niobium is a shiny gray, ductile metal that resembles steel. It is characterized by its high melting point, considerable hardness, and low thermal and electrical conductivity compared to other conductive metals.

Electron Configuration

Electron Levels of a Niobium Atom

The electron configuration of niobium is [Kr] 4d4 5s1, with 2, 8, 18, 12, 1 electrons per shell. This is an atypical configuration for a group 5 element, as the Aufbau principle predicts 4d3 5s2 instead of 4d4 5 s1. The principle fails in this case because it does not account for electron-electron and electron-nucleus interactions. However, similar atypical configurations occur for ruthenium (44), rhodium (45), and palladium (46).

Niobium Isotopes

Niobium has one naturally occurring isotope, niobium-93, which is stable. It also has 32 synthetic radioactive isotopes, ranging in atomic mass from 81 to 113. Of these, niobium-92 is the most stable, with a half-life of 34.7 million years. Niobium-113 is one of the least-stable, with a half-life around 30 milliseconds.

Niobium Abundance and Sources

Niobium is not found free in nature. It occurs in minerals such as columbite and tantalite. These minerals are the primary sources of niobium, with major deposits found in Brazil and Canada. The element’s abundance is about 20 ppm, making it around 34th most common element in the Earth’s crust.

Purification Process

The purification of niobium involves complex processes, including separation from tantalum (with which it is often found) and reduction using hydrogen or other agents.

Uses of Niobium

Around 90% of purified niobium goes to steel production. However, the element has other uses:

  • Steel Alloying: Niobium improves the strength and durability of steel, especially in pipelines and automotive components.
  • Superconducting Magnets: Niobium-tin and niobium-titanium alloys are important in superconducting magnets in MRI machines and particle accelerators.
  • Aerospace Applications: Its high melting point and resistance to corrosion make it ideal for jet engines and rocket subassemblies.
  • Electronics: Niobium finds use in capacitors and electrical components due to its low thermal and electrical conductivity.
  • Lamp Filaments: The first commercial application of niobium was in incandescent lamp filaments, although tungsten quickly replaced it.
  • Coinage Metal: Some countries use niobium in commemorative coins, featuring its ability to form different colors through anodization as a decorative element.
  • Medical Implants: Niobium is highly inert and non-toxic, making it compatible with human tissue. This property leads to its use in medical implants such as pacemakers and orthopedic implants.
  • Jewelry: Niobium is about as easy to work as sterling silver. It is hypoallergenic and popular in jewelry for its vivid permanent anodized colors.

Oxidation States

Niobium has oxidation states ranging from -1 to +5. The +5 state is the most common and stable.

Biological Role and Health Effects

Niobium has no known biological role. In terms of health effects and toxicity, it is relatively inert and not considered hazardous. However, the metal dust irritates skin and eyes and poses a fire risk.

Key Niobium Facts for Scientists

PropertyValue
NameNiobium
SymbolNb
Atomic Number41
Atomic Weight92.90637
Group5
Period5
Blockd-block
Electron Configuration[Kr] 4d4 5s1
Electrons per Shell2, 8, 18, 12, 1
State at Room TemperatureSolid
Melting Point2,477 °C
Boiling Point4,744 °C
Density8.57 g/cm³
Heat of Fusion30 kJ/mol
Heat of Vaporization690 kJ/mol
Molar Heat Capacity24.6 J/(mol·K)
Oxidation States-3, -1, 0, +1, +2, +3, +4, +5
Ionization Energies1st: 652.1 kJ/mol
Atomic Radius146 pm
Covalent Radius164 pm
Crystal StructureBody-centered cubic (bcc)
Thermal Conductivity53.7 W/(m·K)
Electrical Resistivity152 nΩ·m (at 20 °C)
Shear Modulus38 GPa
Bulk Modulus170 GPa
Mohs Hardness6
Magnetic OrderingParamagnetic

Interesting Niobium Facts

  1. Superconducting Properties: Niobium becomes a superconductor at cryogenic temperatures. It has the highest critical temperature (9.2 K) of any elemental superconductor at atmospheric pressure. It also has the highest magnetic penetration depth of any element.
  2. Colorful Anodizing: Anodizing niobium produces a wide array of colors, making it popular in jewelry and other decorative items. This coloration comes from the formation of a thin oxide layer that causes interference effects, similar to oil on water.
  3. Space Elevators: In speculative designs for space elevators, niobium alloys are potential materials for the tether because of their strength and superconducting properties, which could be useful for energy transfer.
  4. Earth’s Core: While not abundant on the Earth’s crust, niobium may be more plentiful in the Earth’s core.
  5. Meteorite Composition: Niobium occurs in meteorites in higher concentrations than on Earth’s surface, providing clues to the formation of the solar system.
  6. Chemical Resilience: It is highly resistant to many chemicals and is useful in equipment for handling corrosive substances.
  7. Optical Uses: Due to its refractive properties, niobium finds use in special optical lenses.
  8. Catalytic Properties: Niobium oxides and some niobium compounds are catalysts in the petrochemical industry, aiding in the breakdown of crude oil into gasoline and other products.
  9. Inconsistent Crystal Structure: The body-centered cubic structure that niobium displays from absolute zero to its melting point isn’t the whole story. Crystallography reveals inconsistencies in the structure, so research in this area is ongoing.
  10. Neutron Transparency: Because of its low thermal neutron capture cross-section, niobium is useful in making neutron transparent structures in the nuclear industry.

References

  • Emsley, John (2001). “Niobium”. Nature’s Building Blocks: An A-Z Guide to the Elements. Oxford, England: Oxford University Press. pp. 283–286. ISBN 978-0-19-850340-8.
  • Hatchett, Charles (1802). “An analysis of a mineral substance from North America, containing a metal hitherto unknown”. Philosophical Transactions of the Royal Society of London. 92: 49–66. doi:10.1098/rspl.1800.0045
  • Lide, David R. (2004). “The Elements”. CRC Handbook of Chemistry and Physics (85th ed.). CRC Press. pp. 4–21. ISBN 978-0-8493-0485-9.
  • Soisson, Donald J.; McLafferty, J. J.; Pierret, James A. (1961). “Staff-Industry Collaborative Report: Tantalum and Niobium”. Industrial and Engineering Chemistry. 53 (11): 861–868. doi:10.1021/ie50623a016
  • Wollaston, William Hyde (1809). “On the Identity of Columbium and Tantalum”. Philosophical Transactions of the Royal Society. 99: 246–252. doi:10.1098/rstl.1809.0017