Periodic Table > Tantalum


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

For more information on Murray Robertson’s image see Uses and properties facts below.


Fact box terminology

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.

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

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.

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.

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

Density (g cm-3)
Density is the mass of a substance that would fill 1 cm3 at room temperature.

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 3017 oC, 5463 oF, 3290 K 
Period Boiling point 5455 oC, 9851 oF, 5728 K 
Block Density (g cm-3) 16.4 
Atomic number 73  Relative atomic mass 180.948  
State at 20°C Solid  Key isotopes 180Ta, 181Ta 
Electron configuration [Xe] 4f145d36s2  CAS number 7440-25-7 
ChemSpider ID 22395 ChemSpider is a free chemical structure database

Uses and properties 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.


The description of the element in its natural form.

Uses and properties

Image explanation
An image of an abstracted human skull, banded with strips or ‘plates’. This reflects the use of the element in medical prosthetics. The background design is based on a scene from an Ancient Greek vase depicting the mythological figure Tantalus, a reference to the origin of the element’s name.
A shiny, silvery metal that is very resistant to corrosion.
One of the main uses of tantalum is in the production of electronic components. An oxide layer which forms on the surface of tantalum can act as an insulating (dielectric) layer. Because tantalum can be used to coat other metals with a very thin layer, a high capacitance can be achieved in a small volume. This makes tantalum capacitors attractive for portable electronics such as mobile phones.

Tantalum causes no immune response in mammals, so has found wide use in the making of surgical implants. It can replace bone, for example in skull plates; as foil or wire it connects torn nerves; and as woven gauze it binds abdominal muscle.

It is very resistant to corrosion and so is used in equipment for handling corrosive materials. It has also found uses as electrodes for neon lights, AC/DC rectifiers and in glass for special lenses.

Tantalum alloys can be extremely strong and have been used for turbine blades, rocket nozzles and nose caps for supersonic aircraft.
Biological role
Tantalum has no known biological role. It is non-toxic.
Natural abundance
Tantalum is sometimes, but only rarely, found uncombined in nature. It occurs mainly in the mineral columbite-tantalite, which also contains other metals including niobium. It is mined in many places including Australia, Canada and Brazil. There are several complicated steps involved in separating the tantalum from the niobium. A lot of tantalum is obtained commercially 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) 2.22 Covalent radius (Å) 1.58
Electron affinity (kJ mol-1) 31.068 Electronegativity
(Pauling scale)
Ionisation energies
(kJ mol-1)

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 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.


The country with the largest reserve base.

Reserve 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.

Political stability of top producer

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 distribution (%), Production Concentration and Governance Factor scores are summed and then divided by 2, to provide an overall Relative Supply Risk Index.

Supply risk

Relative supply risk 7.1
Crustal abundance (ppm) 0.7
Recycling rate (%) <10
Substitutability Medium
Production concentration (%) 25
Reserve distribution (%) 54
Top 3 producers
  • 1) Brazil
  • 2) Rwanda
  • 3) China
Top 3 reserve holders
  • 1) Brazil
  • 2) Australia
  • 3) Mozambique
Political stability of top producer 48.1
Political stability of top reserve holder 48.1

Oxidation states and 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


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.

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 and isotopes

Common oxidation states 5
Isotopes Isotope Atomic mass Natural abundance (%) Half life Mode of decay
  180Ta 179.947 0.012 3.65 x 1016
        4.5 x 1016 β- 
        > 2.0 x 1016 EC 
  181Ta 180.948 99.988

Pressure and temperature - advanced terminology

Specific heat capacity (J kg-1 K-1)

Specific heat capacity is the amount of energy needed to change the temperature of a kilogram 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 and temperature data – advanced

Specific heat capacity
(J kg-1 K-1)
140 Young's modulus (GPa) 185.7
Shear modulus (GPa) 69.2 Bulk modulus (GPa) Unknown
Vapour pressure  
Temperature (K)
400 600 800 1000 1200 1400 1600 1800 2000 2200 2400
Pressure (Pa)
- - - - - - - - 3.36
x 10-10
x 10-8
x 10-7
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Tantalum was reported as a new metal in 1802 by Anders Gustav Ekeberg at Uppsala University, Sweden. However, when William Wollaston analysed the minerals from which it had been extracted he declared it was identical to niobium which has been discovered the year previously. It was as a result of their similarity that there was confusion regarding their identification. These two elements often occur together and, being chemically very similar, were difficult to separate by the methods available at the time of the discovery.

It was not until 1846 that Heinrich Rose separated tantalum and niobium and proved conclusively that they were different elements, and yet his sample of tantalum was still somewhat impure, and it was not until 1903 that pure tantalum was produced by Werner von Bolton.

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Listen to Tantalum Podcast
Transcript :

Chemistry in Its Element - Tantalum


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 we put down our portable game stations, stop taking photos and turn off our phones, to give some respect to the element that's helped make our modern lifestyles possible.   Here's John Whitfield. 

John Whitfield   

Stop a minute. Check your pockets. Rummage in your bag. Chances are that somewhere in there you'll turn up a mobile phone. Although it might take a few moments, and you might not even be sure where your phone has got to, so light and compact have these ubiquitous devices become. 

We've got tantalum to thank for making our mobiles so easy to lose. It's this element that's allowed them to evolve from the house bricks of the nineteen eighties to the Star-trek style communicators of the noughties. 

A mixture of powdered tantalum and tantalum oxide is used in mobile phone capacitors, components that store electrical charge and control the flow of current. What makes the elements ideal for phones, and other dinky electronic devices, such as handheld game consoles, laptops and digital cameras, is that the metal is extremely good at conducting both heat and electricity, meaning that it can be used in small components that don't crack up under pressure.   

Tantalum, you might say, is the strong, silent type. Its properties have made it an element that gets inside things, hidden but influential. 

The boom in mobile electronics means that tantalum is now more in demand, and probably more widely known than at any point since it was discovered in 1802.  It's also made tantalum one of those raw materials that fuel and provoke conflict, leading to some people talking about 'blood tantalum'   

Tantalum was discovered by the Swedish chemist Anders Ekeberg, who extracted the metal from mineral samples. Tantalus was a king in greek mythology who, after stealing secrets from the gods, was punished by being forced to stand in a pool of water that flowed away from him every time he bent his head to drink. The new metal's refusal to react when immersed in acid reminded Ekeberg of the king's plight.   

After Ekeberg's discovery, however, tantalum fell prey to a case of mistaken identity, with many chemists believing that it was one and the same as columbium, another metal described at around the same time.   

The two, which have similar chemical properties and nearly always occur together in nature, were not unequivocally shown to be different until the middle of the nineteenth century, when columbium was renamed niobium, after Niobe, the daughter of Tantalus.   

Both are rare earth elements. Tantalum now sits below niobium in the periodic table. It has an atomic number of 73, and an atomic weight of just under 181. It always takes a valence of 5, so, for example, its oxide contains two atoms of tantalum and five of oxygen. 

In its pure state, tantalum is a grey-blue metal, which can be polished to a silvery sheen. You can hammer it into sheets, and draw it into wires. And, as Ekeberg discovered, it's tough stuff. Tantalum alloys turn up in hot places such as jet engines and nuclear reactors because the metal's melting point is around 3,000 degrees centigrade - among the metals, only tungsten and rhenium are higher.   

Tantalum's chemical inertness has also led to it being used in surgical instruments and implants such as pacemakers - it's neither corroded by body fluids, nor does it irritate living tissue.   

One promising medical application is in replacement joints. A layer of metal about 50 micrometres thick is deposited onto a porous carbon skeleton to create a rigid material that has a similar structure to bone itself, meaning that once the new joint is in the body, the patient's bone and soft tissue can bond with and grow into the implant.   

Tantalum is relatively rare: it's the fiftieth commonest element in the earth's crust. There are only 40 miligrams of the stuff in a cell phone, but with there currently being about two phones for every three people on Earth, that's still a lot of tantalum. Last year more than two-and-a-half million kilograms were used, two thirds of that in electronic devices. 

Historically, the most important source of the metal was Australia, but in late 2008, the world's largest mine in western Australia, which had supplied about 30% of the world's total, was mothballed by it's owners, citing slack demand from manufacturers in the global economic downturn, and cheaper sources of the metal elsewhere. 

Elsewhere in this case means Central Africa. The Democratic Republic of Congo in particular contains large deposits of a mineral containing a mix of tantalum and niobium compounds, called columbite-tantalite, colloquially known as coltan. 

Profits from coltan mining have helped fund the opposing sides in the DRC's appalling civil war, which has killed more than 5 million people since 1998. The country's neighbours have also been accused of smuggling the metal out of the DRC. Human rights groups, and the United Nations, have condemned the trade, meaning that although tantalum might be chemically inert, in the last decade it's become politically explosive. 

Meera Senthilingam 


So an element under political scrutiny due to its wide range of uses in mobile phones, jet engines, nuclear reactors and even replacement joints.   That was John Whitfield with the tantalising story of Tantalum.   Now next week, we've got an element whose founder is under question.   

Eric Scerri   

It was not until the twentieth century before protactinium was first discovered.   Of course it depends on what one really means by the discovery of an element.  Does it mean somebody realizing that a mineral contains a new element, or does it mean the first time an element is actually isolated?  Depending on what choice is made the discovery of protactinium can be assigned to different scientists.  And in the case of protactinium there is an even further complication. 

Meera Senthilingam 

So join UCLA's Eric Scerri who will be revealing this complication in next week's Chemistry in its Element.   Until then I'm Meera Senthilingam and thank you for listening.   



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.     


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Visual Elements images and videos
© Murray Robertson 2011.



W. M. Haynes, ed., CRC Handbook of Chemistry and Physics, CRC Press/Taylor and Francis, Boca Raton, FL, 95th Edition, Internet Version 2015, accessed December 2014.
Tables of Physical & Chemical Constants, Kaye & Laby Online, 16th edition, 1995. Version 1.0 (2005), accessed December 2014.
J. S. Coursey, D. J. Schwab, J.J. Tsai, and R. A. Dragoset, Atomic Weights and Isotopic Compositions(version 3.0), 2010, National Institute of Standards and Technology, Gaithersburg, MD, accessed December 2014.
T. L. Cottrell, The Strengths of Chemical Bonds, Butterworth, London, 1954.


Uses and properties

John Emsley, Nature’s Building Blocks: An A-Z Guide to the Elements, Oxford University Press, New York, 2nd Edition, 2011.
Thomas Jefferson National Accelerator Facility - Office of Science Education, It’s Elemental - The Periodic Table of Elements, accessed December 2014.
Periodic Table of Videos, accessed December 2014.


Supply risk data

Derived in part from material provided by the British Geological Survey © NERC.


History text

© John Emsley 2012.



Produced by The Naked Scientists.


Periodic Table of Videos

Created by video journalist Brady Haran working with chemists at The University of Nottingham.