Periodic Table > Niobium
 

Terminology


Allotropes
Some elements exist in several different structural forms, these are called allotropes.


For more information on Murray Robertson’s image see Uses/Interesting Facts below.

 

Fact Box Terminology


Group
Elements appear in columns or ‘groups’ in the periodic table. Members of a group typically have similar properties and electron configurations in their outer shell.


Period
Elements are laid out into rows or ‘periods’ so that similar chemical behaviour is observed in columns.


Block
Elements are organised into blocks by the orbital type in which the outer electrons are found. These blocks are named for the characteristic spectra they produce: sharp, principal, diffuse, and fundamental.


Atomic Number
The number of protons in the nucleus.


Atomic Radius/non -bonded (Å)
based on Van der Waals forces (where several isotopes exist, a value is presented for the most prevalent isotope). These values were calculated using a multitude of methods including crystallographic data, gas kinetic collision cross sections, critical densities, liquid state properties, for more details please refer to the CRC Handbook of Chemistry and Physics.


Electron Configuration
The arrangements of electrons above the last (closed shell) noble gas.


Isotopes
Elements are defined by the number of protons in its centre (nucleus), whilst the number of neutrons present can vary. The variations in the number of neutrons will create elements of different mass which are known as isotopes.


Melting Point (oC)
The temperature at which the solid-liquid phase change occurs.


Melting Point (K)
The temperature at which the solid-liquid phase change occurs.


Melting Point (oF)
The temperature at which the solid-liquid phase change occurs.


Boiling Point (oC)
The temperature at which the liquid-gas phase change occurs.


Boiling Point (K)
The temperature at which the liquid-gas phase change occurs.


Boiling Point (oF)
The temperature at which the liquid-gas phase change occurs.


Sublimation
Elements that do not possess a liquid phase at atmospheric pressure (1 atm) are described as going through a sublimation process.


Density (kgm-3)
Density is the weight of a substance that would fill 1 m3 (at 298 K unless otherwise stated).


Relative Atomic Mass
The mass of an atom relative to that of Carbon-12. This is approximately the sum of the number of protons and neutrons in the nucleus. Where more than one isotope exists the value given is the abundance weighted average.


Key Isotopes (% abundance)
An element must by definition have a fixed number of protons in its nucleus, and as such has a fixed atomic number, however variants of an element can exist with differing numbers of neutrons, and hence a different atomic masses (e.g. 12C has 6 protons and 6 neutrons and 13C has 6 protons and 7 neutrons).


CAS number
The Chemical Abstracts Service registry number is a unique identifier of a particular chemical, designed to prevent confusion arising from different languages and naming systems (where several isotopes exist, a value is presented for the most prevalent isotope).

Fact Box

 
Group Melting point 2477 oC, 4490.6 oF, 2750.15 K 
Period Boiling point 4744 oC, 8571.2 oF, 5017.15 K 
Block Density (kg m-3) 8578 
Atomic number 41  Relative atomic mass 92.906  
State at room temperature Solid  Key isotopes 93Nb 
Electron configuration [Kr] 4d45s1  CAS number 7440-98-7 
ChemSpider ID 22378 ChemSpider is a free chemical structure database
 

Interesting Facts terminology


Image Explanation

Murray Robertson is the artist behind the images which make up Visual Elements. This is where the artist explains his interpretation of the element and the science behind the picture.


Natural Abundance

Where this element is most commonly found in nature.


Biological Roles

The elements role within the body of humans, animals and plants. Also functionality in medical advancements both today and years ago.


Appearance

The description of the element in its natural form.

Uses / Interesting Facts

 
Image explanation
This icon reflects the use of Niobium and its alloys in the aviation industry.
Appearance
A silvery metal that is very resistant to corrosion and is added in small amounts to improve stainless steels.
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.
Natural abundance
The main source of this element is in the mineral columbite, which can be found in Canada, Brazil, Australia, Nigeria and elsewhere. However, it is commercially prepared as a by-product of tin extraction.
 
Atomic Data Terminology

Atomic radius/non -bonded (Å)
Based on Van der Waals forces (where several isotopes exist, a value is presented for the most prevalent isotope). These values were calculated using a multitude of methods including crystallographic data, gas kinetic collision cross sections, critical densities, liquid state properties,for more details please refer to the CRC Handbook of Chemistry and Physics.


Electron affinity (kJ mol-1)
The energy released when an additional electron is attached to the neutral atom and a negative ion is formed (where several isotopes exist, a value is presented for the most prevalent isotope). *


Electronegativity (Pauling scale)
The degree to which an atom attracts electrons towards itself, expressed on a relative scale as a function bond dissociation energies, Ed in eV. χA - χB =(eV)-1/2sqrt(Ed(AB)-[Ed(AA)+Ed(BB)]/2), with χH set as 2.2 (where several isotopes exist, a value is presented for the most prevalent isotope).


1st Ionisation energy (kJ mol-1)
The minimum energy required to remove an electron from a neutral atom in its ground state (where several isotopes exist, a value is presented for the most prevalent isotope).


Covalent radius (Å)
The size of the atom within a covalent bond, given for typical oxidation number and coordination (where several isotopes exist, a value is presented for the most prevalent isotope). ***

Atomic Data

 
Atomic radius, non-bonded (Å) 2.180 Covalent radius (Å) 1.56
Electron affinity (kJ mol-1) 88.381 Electronegativity
(Pauling scale)
1.600
Ionisation energies
(kJ mol-1)
 
1st
652.129
2nd
1350.794
3rd
2415.991
4th
3695.385
5th
4877.330
6th
9846.996
7th
12060.657
8th
-
 

Mining/Sourcing Information

Data for this section of the data page has been provided by the British Geological Survey. To review the full report please click here or please look at their website here.


Key for numbers generated


Governance indicators

1 (low) = 0 to 2

2 (medium-low) = 3 to 4

3 (medium) = 5 to 6

4 (medium-high) = 7 to 8

5 (high) = 9


Reserve base distribution

1 (low) = 0 to 30 %

2 (medium-low) = 30 to 45 %

3 (medium) = 45 to 60 %

4 (medium-high) = 60 to 75 %

5 (high) = 75 %

(Where data are unavailable an arbitrary score of 2 was allocated. For example, Be, As, Na, S, In, Cl, Ca and Ge are allocated a score of 2 since reserve base information is unavailable. Reserve base data are also unavailable for coal; however, reserve data for 2008 are available from the Energy Information Administration (EIA).)


Production Concentration

1 (low) = 0 to 30 %

2 (medium-low) = 30 to 45 %

3 (medium) = 45 to 60 %

4 (medium-high) = 60 to 75 %

5 (high) = 75 %


Crustal Abundance

1 (low) = 100 to 1000 ppm

2 (medium-low) =10 to 100 ppm

3 (medium) = 1 to 10 ppm

4 (medium-high) = 0.1 to 1 ppm

5 (high) = 0.1 ppm

(Where data are unavailable an arbitrary score of 2 was allocated. For example, He is allocated a score of 2 since crustal abundance data is unavailable.)


Explanations for terminology


Crustal Abundance (ppm)

The abundance of an element in the Earth's crust in parts-per-million (ppm) i.e. The number of atoms of this element per 1 million atoms of crust.


Sourced

The country with the largest reserve base.


Reserve Base Distribution

This is a measure of the spread of future supplies, recording the percentage of a known resource likely to be available in the intermediate future (reserve base) located in the top three countries.


Production Concentrations

This reports the percentage of an element produced in the top three countries. The higher the value, the larger risk there is to supply.


Total Governance Factor

The World Bank produces a global percentile rank of political stability. The scoring system is given below, and the values for all three production countries were summed.


Relative Supply Risk Index

The Crustal Abundance, Reserve Base Distribution, Production Concentration and Governance Factor scores are summed and then divided by 2, to provide an overall Relative Supply Risk Index.

Supply Risk

 
Scarcity factor 8.0
Country with largest reserve base Brazil
Crustal abundance (ppm) 8
Leading producer Brazil
Reserve base distribution (%) 86.70
Production concentration (%) 95.80
Total governance factor(production) 6
Top 3 countries (mined)
  • 1) Brazil
  • 2) Canada
  • 3) Australia
Top 3 countries (production)
  • 1) Brazil
  • 2) Canada
  • 3) Rwanda
 

Oxidation states/ Isotopes


Key for Isotopes


Half Life
  y years
  d days
  h hours
  m minutes
  s seconds
Mode of decay
  α alpha particle emission
  β negative beta (electron) emission
  β+ positron emission
  EC orbital electron capture
  sf spontaneous fission
  ββ double beta emission
  ECEC double orbital electron capture

Terminology


Common Oxidation states
The oxidation state of an atom is a measure of the degree of oxidation of an atom. It is defined as being the charge that an atom would have if all bonds were ionic. Free atoms have an oxidation state of 0, and the sum of oxidation numbers within a substance must equal the overall charge.


Important Oxidation states
The most common oxidation states of an element in its compounds.


Isotopes
Elements are defined by the number of protons in its centre (nucleus), whilst the number of neutrons present can vary. The variations in the number of neutrons will create elements of different mass which are known as isotopes.

Oxidation States / Isotopes

 
Common oxidation states 5, 3
Isotopes Isotope Atomic mass Natural abundance (%) Half life Mode of decay
  93Nb 92.906 100
 

Pressure and Temperature - Advanced Terminology


Molar Heat Capacity (J mol-1 K-1)

Molar heat capacity is the energy required to heat a mole of a substance by 1 K.


Young's modulus (GPa)

Young's modulus is a measure of the stiffness of a substance, that is, it provides a measure of how difficult it is to extend a material, with a value given by the ratio of tensile strength to tensile strain.


Shear modulus (GPa)

The shear modulus of a material is a measure of how difficult it is to deform a material, and is given by the ratio of the shear stress to the shear strain.


Bulk modulus (GPa)

The bulk modulus is a measure of how difficult to compress a substance. Given by the ratio of the pressure on a body to the fractional decrease in volume.


Vapour Pressure (Pa)

Vapour pressure is the measure of the propensity of a substance to evaporate. It is defined as the equilibrium pressure exerted by the gas produced above a substance in a closed system.

Pressure / Temperature - Advanced

 
Molar heat capacity
(J mol-1 K-1)
24.6 Young's modulus (GPa) 104.9
Shear modulus (GPa) 37.5 Bulk modulus (GPa) Unknown
Vapour pressure  
Temperature (K)
400 600 800 1000 1200 1400 1600 1800 2000 2200 2400
Pressure (Pa)
- - - - - - 2.32
x 10-11
9.54
x 10-9
1.17
x 10-6
5.98
x 10-5
1.58
x 10-3
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History

When examining minerals in the British Museum in 1801, Charles Hatchett was intrigued by a specimen labelled columbite. He suspected it contained a new metal, and he was right. He heated a sample with potassium carbonate, dissolved the product in water, added acid and got a precipitate. However, further treatment did not produce the element itself, although he named it columbium, and so it was known for many years.


Others doubted columbium, especially after the discovery of tantalum which happened the following year. These metals occur together in nature, and are difficult to separate. In 1844 the German chemist Heinrich Rose proved that columbite contained both elements and he renamed columbium niobium.


A sample of the pure metal was produced in 1864 by Christian Blomstrand who reduced niobium chloride by heating it with hydrogen gas.

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Podcasts

Listen to Niobium Podcast
Transcript :

Chemistry in its element - niobium


(Promo)

You're listening to Chemistry in its element brought to you by Chemistry World, the magazine of the Royal Society of Chemistry

(End promo)

Meera Senthilingam

This week, an element with some contradiction, as its namesake weeps, yet its chemistry is impassive. Here's Jon Steed:

Jon Steed

Niobium. What an evocative name! The element was christened after Niobe, the daughter of Tantalus in Greek mythology. Tantalus has an element named after him as well; tantalum which falls directly below niobium in the periodic table. Niobe had a fairly hard time of it. She was foolish enough to suggest that rather than worshipping invisible gods, it might be a nice idea to appreciate real people for a change. The Greek gods weren't very forgiving of this kind of hubris and as punishment killed all, or at least most, of her twelve children; the niobids. As a result Niobe fled to Mount Sipylus and was turned into stone. There is to this day a rock formation in the Aegean region of Turkey termed the 'weeping rock' that resembles a woman's face, purportedly Niobe's. Water seeps through the porous limestone of the weeping rock and is said to resemble Niobe's unceasing tears at the fate of the niobids. Niobe's apparent petrification and the subsequent seeping of mineral-laden water through the rock calls to mind the real chemical phenomenon of petrifying wells such as the one at Mother Shipton's Cave in Knaresborough in North Yorkshire. The evaporation of the salt-saturated water and subsequent mineral deposition means that these wells really can apparently turn common objects to stone. 

 

Placing Niobe and her father Tantalus next to one another in the periodic table is no accident. Both niobium and tantalum are found together in the mineral columbite, a mixed oxide that also contains iron and manganese, and they have similar chemical and physical properties. In fact Niobium was originally named columbium after Columbia, because of its discovery in a mineral sent from America in 1801. The following half-century saw a great deal of confusion about exactly which possible new tantalum-like elements were present in these kinds of minerals and initially a number of Tantalus's children became immortalised as elements, with names such as pelopium, ilmenium and dianium. In the end only niobium survived. In the US niobium was called columbium, symbol Cb, all the way up until its official christening by the International Union of Pure and Applied Chemistry in 1950. The last paper published by the American Chemical Society that mentions columbium dates from 1953, with the rather unexciting title "Photometric Determination of Columbium, Tungsten, and Tantalum in Stainless Steels". This paper does hint at one of niobium's major uses though, as we will see. The 2010 Aldrich Catalogue of Fine Chemicals still has Columbium as an explanatory subheading for any confused Americans out there.

 

In fact, in contrast to the plucky Niobe, niobium is a pretty impassive element. It doesn't even react with the very oxidising acid aqua regia and, like tantalum, is inert to bodily fluids. This impassivity, coupled with its tendency to be coloured by anodisation means that it is sometimes used in jewellery and coinage. The anodising process results in a thin oxide layer that creates a range of permanent colours by diffraction of light. Since 2003, Austria has produced a series of silver-niobium euro coins with a niobium centre coloured blue, green, brown, purple, violet or yellow. Like the better known tungsten, niobium also forms a range of colourful oxide 'bronzes' ranging from deep blue to red depending on the degree of reduction.

 

  Perhaps the most exciting modern day role of niobium, however, is in superconducting niobium-titanium alloy fibres. Niobium-titanium is a superconducting at temperatures below ten Kelvin and is used in a number of large superconducting magnets such as the Tevatron accelerator at Fermilab and most recently the Large Hadron Collider, where the niobium-containing magnets are cooled to 1.9 Kelvin and operate at magnetic fields of up to 8.3 Tesla. You can also find it in the superconducting magnets in hospital MRI scanners.

 

Niobium is a useful metal in a range of specialist alloys. In amounts as low as 0.1 per cent it has a significant strengthening effect on steel, making it suitable for use in gas pipelines for example. It is also involved in some highly temperature-stable superalloys used for engine parts in the aerospace industry.

 

Niobium very nearly became quite literally a household element because of its early role as the filament in incandescent light bulbs. Its impassivity and high melting point of 2468 centigrade lent themselves to this application but it was swiftly replaced by the even higher melting tungsten. Niobium is also a fairly dense element and it is this density that might account for its apparent rarity. Occurring at only twenty parts per million, it is 33rd in the hall of fame of most common elements in the Earth's crust. This surprisingly low value might arise from the 'missing' niobium sinking to the Earth's core during the planet's formation.

 

You don't tend to see a great many publications in the inorganic chemistry literature on niobium chemistry, although the metal is not particularly expensive so perhaps all that will change in this credit-crunched era. A classic paper is Dick Schrock's 1979 review of the chemistry of niobium and tantalum alkylidene complexes - compounds with a double bond between the metal and carbon. This paper contains a picture of one of my favourite organometallic compounds - actually a tantalum compound - in which the metal is sandwiched between two organic rings and bound to two delightfully simple carbon fragments; CH2 and CH3. This structure presages a wide range sandwich-type, metal based catalysts. 

 

In terms of niobium molecular pin-ups, one of the most elegant is the very symmetrical cluster formed from an octahedron of six niobium ions and eighteen chlorides. An ion that highlight's niobium's tendency to form large, exotic multi-metallic clusters with halides and oxides.

 

When you look at the great sprawling mass of the periodic table, it's easy for your eye to get lost in the swathe of exotically and confusingly named transition metals somewhere around the dip in the middle. I hope that you will let the example of niobium remind you that there's nothing to weep about. The subtleties of these elements aren't too petrifying, and with a little creativity you may give birth to some chemistry that even the vengeful, ancient gods can be proud of.

Meera Senthilingham

Providing colour, superconducting abilities and molecular pin-ups - certainly something for the gods to be proud of. That was Durham University's Jon Steed with the tantalising chemistry of the element niobium.

Now next week, an element whose founder clearly didn't believe in risk assessments.

Lars Öhrström

Frequently after more spectacular chemistry demonstrations, the scientist on stage will warn the audience 'not to try this at home'. One person who certainly did not listen to such warnings was Swedish chemist Jöns Jacob Berzelius. Instead, he and his co-workers performed many groundbreaking experiments in the kitchen of his flat in the corner of Nybrogatan and Riddargatan in Stockholm. In 1815, for example, Berzelius isolated a new element from a mineral sent to him from the Swedish mining town of Falun and named it thorium after the Scandinavian god of thunder, Thor. Only to realise a few years later that he was wrong and what he though was a new element was in fact yttrium phosphate.

However, in 1828, by then long since world famous and credited with discovering three other elements, he received a strange mineral sample from the reverend Hans Esmark in Norway. In his new laboratory at the Swedish Royal Academy of Sciences, Berzelius isolated yet another element, this element is what we now call thorium. 

Meera Senthilingham

And now you know its discovery, join Lars Öhrström from the Chalmers tekniska högskola in Sweden to find out the chemistry and applications of thorium in next week's Chemistry in its element. Until then, I'm Meera Senthilinghma and thankyou for listening.

(Promo)

Chemistry in its element  is brought to you by the Royal Society of Chemistry and produced by thenakedscientists dot com. There's more information and other episodes of Chemistry in its element on our website at chemistryworld dot org forward slash elements.     

(End promo)

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References

 
Images:  Visual Elements © Murray Robertson 2011
Mining and Sourcing data:  British Geological Survey – natural environment research council.
Text:  John Emsley Nature’s Building Blocks: An A-Z Guide to the Elements, Oxford University Press, 2nd Edition, 2011.
Additional information for platinum, gold, neodymium and dysprosium obtained from Material Value Consultancy Ltd www.matvalue.com
Data: CRC Handbook of Chemistry and Physics, CRC Press, 92nd Edition, 2011.
G. W. C. Kaye and T. H. Laby Tables of Physical and Chemical Constants, Longman, 16th Edition, 1995.
Members of the RSC can access these books through our library.