Niobium Element: Facts, Characteristics, and Uses

The crystal structure of niobium is BCC.―body centered cubic' arrangement of molecules. In case of a BCC arrangement, atoms are arranged one each at the 8 corners of the unit cell, and one atom lies at the center of the cube.

Niobium pronounced as 'nye-OH-bee-um ' is a transition metal belonging to group 5 of the periodic table. It is known to occur in a black-colored mineral called niobite. This mineral is an ore containing tantalum, besides niobium. Traces of this element are found in some varieties of plants. However, it doesn't have any adverse effects on the environment.

Niobium usually occurs in the solid form and is used in many alloys. One common example is steel which uses 0.1% of this element. This meager amount of niobium increases the strength of steel to a considerable extent. This element has the tendency to remain nonreactive when it comes in contact with most of the strong acids. Only a few acids in the hot and concentrated form can react with niobium.

◈ The properties of niobium are similar to that of element tantalum. According to Greek mythology, tantalum derives its name from King Tantalus, while niobium derives its name from the word 'Niobe', which was the name of king's daughter.
◈ It was discovered by an English chemist Charles Hatchett, in the year 1801.
◈ This element was known as 'columbium' in the U.S., for almost about 100 years and known by its actual name in Europe.

◈ Its parent ore was discovered early in the year 1734 by John Winthrop the Younger.
◈ This element derived its name from International Union of Pure and Applied Chemistry (IUPAC) in the year 1950.
◈ It is the 33rd most commonly occurring element in the Earth's crust.

◈ Niobium is still referred to as columbium (Cb) by some metallurgical engineers.
◈ Some compounds of this element are known to be highly toxic.
◈ It has more than 10 radioactive isotopes, but only one stable isotope.

◈ The density of niobium is 8.5 g/cm³.
◈ Its thermal conductivity is 54 W m^-1 K^-1.
◈ Its electrical resistivity at a temperature of 0ºC 15.2 × 10^-8 Ohm.
◈ The specific heat capacity of this element is 265 J/kg/K.
◈ The magnetic ordering for this element is said to be paramagnetic.
◈ The melting point of niobium is 2410°C.

◈ The Brinell's hardness of this metal is 736 MN m^-2.
◈ The value of Young's modulus is 104.9 GPa.
◈ Its coefficient of thermal expansion is 7.3 × 10-6 K^-1.
◈ The first, second, and third ionization energies of this element are 652.13 kJ/mol, 1381.68 kJ/mol, and 2416.01 kJ/mol, respectively.
◈ The boiling point of this element is 5100°C.

◈ The velocity of sound in a niobium rod at a temperature of about 20ºC is equal to 3.4 X 10³ m/sec.
◈ The shear modulus of this element is 37.5 GPa.
◈ The Vickers hardness of niobium is 1320 MN m^-2, and mineral hardness is 6.
◈ It has a layer of oxide on its surface, which makes this element resistant to corrosion.
◈ Niobium is known to be soft, malleable, ductile.

◈ The atomic number of niobium is 41, which implies that it consists of 41 electrons and 41 protons. Its standard atomic weight is 92.91 g/mol¹.
◈ The electronic configuration of niobium (in terms of a noble element) is represented as:
[Kr] 4d⁴ 5s¹.
◈ It belongs to group 5 and block d of the periodic table.

◈ The standard atomic mass of niobium is nearly 92.91 g.mol^-1.
◈ The molar volume of this element is 10.83 cm³.
◈ The metal oxidizes at temperatures of above 200ºC.

The shell diagrams comprise the nucleus, shells, and electrons placed in these shells. The image displayed below represents the shell diagram of niobium. The innermost layer is the first orbital containing 2 electrons. The outermost layer is the fifth orbital containing 1 electron.

◈ Niobium being inert and hypoallergenic makes for a good material in jewelry making (rings, earrings, etc.)
◈ Niobium alloys are widely used in the medical field for making surgical implants. They do not interfere with the human tissue.
◈ Its compound with selenium, called 'niobium diselenide', is used as a lubricant because of its property of being stable even at high temperatures.

◈ It is coupled with other metals to make super-alloys. Ferroniobium is one such alloy, which contains about 60-70% niobium.
◈ A carbide of this element, called niobium carbide, is used in cutting tools.
◈ It used in particle accelerators to make accelerating structures.
◈ It is used in making superconducting magnets.

◈ The compound of niobium with silica, called 'niobium silicide', is used as a refractory material.
◈ Niobium steel is used in making skateboards.

As we know that niobium occurs as a constituent of ores or minerals, it is found in many countries such as Zaire, Russia, Canada, Kenya, Brazil, and Nigeria.