Tantalum (Ta)
transition-metalSolid
Standard Atomic Weight
180.94788 uElectron configuration
[Xe] 6s2 4f14 5d3Melting point
3016.85 °CBoiling point
5457.85 °CDensity
1.64e+4 kg/m³Oxidation states
−3, −1, 0, +1, +2, +3, +4, +5Electronegativity (Pauling)
1.5Ionization energy (1st)
7.549571 eVDiscovery year
1802Atomic radius
145 pmDetails
Tantalum is a dense, refractory transition metal in group 5, closely associated geologically and chemically with niobium. It is noted for exceptional resistance to corrosion, a very high melting point, and the stable, high-permittivity oxide film that forms on its surface. Most natural tantalum is ¹⁸¹Ta, with a small contribution from the long-lived nuclear isomer ¹⁸⁰ᵐTa. Its chemistry is dominated by the +5 oxidation state.
Tantalum is a gray, heavy, and very hard metal. When pure, it is ductile and can be drawn into fine wire, which is used as a filament for evaporating metals such as aluminum. Tantalum is almost completely immune to chemical attack at temperatures below 150°C, and is attacked only by hydrofluoric acid, acidic solutions containing the fluoride ion, and free sulfur trioxide. Alkalis attack it only slowly. At high temperatures, tantalum becomes much more reactive. The element has a melting point exceeded only by tungsten and rhenium. Tantalum is used to make a variety of alloys with desirable properties such as high melting point, high strength, good ductility, etc. Tantalum has a good "gettering" ability at high temperatures, and tantalum oxide films are stable and have good rectifying and dielectric properties.
The name derives from the Greek mythological character Tantalus who was banished to Hades, the region of lost souls where he was placed up to his chin in water, which receded whenever he tried to drink it, and under branches of fruit, which drew back whenever he tried to pick their fruit. This name was selected because of the insolubility of tantalum in acids; thus, when placed in the midst of acids, it is incapable of taking any of them up. Tantalum was discovered by the Swedish chemist and mineralogist Anders- Gustav Ekeberg in 1802.
Tantalum was discovered by Anders Gustaf Ekenberg, a Swedish chemist, in 1802 in minerals obtained from Ytterby, Sweden. Many scientists believed that he had only discovered an allotrope of niobium, an element that is chemically similar to tantalum. The issue was finally settled in 1866 when, Jean Charles Galissard de Marignac, a Swiss chemist, proved that tantalum and niobium were two distinct elements. The first relatively pure samples of tantalum were first produced in 1907. Today, tantalum is primarily obtained from the minerals columbite ((Fe, Mn, Mg)(Nb, Ta)2O6), tantalite ((Fe, Mn)(Ta, Nb)2O6) and euxenite ((Y, Ca, Er, La, Ce, U, Th)(Nb, Ta, Ti)2O6).
Named after Tantalos, a Greek a mythological character, father of Niobe. Discovered in 1802 by Ekeberg, but many chemists thought niobium and tantalum were identical elements until Rowe in 1844, and Marignac, in 1866, showed that niobic and tantalic acids were two different acids. The early investigators only isolated the impure metal. The first relatively pure ductile tantalum was produced by von Bolton in 1903. Tantalum occurs principally in the mineral columbite-tantalite.
Pure tantalum is a hard, heavy, lustrous metal with a gray to blue-gray metallic surface. It is ductile when sufficiently pure but becomes less workable when contaminated by oxygen, nitrogen, hydrogen, or carbon. A thin oxide film passivates the surface in air.
Tantalum is widely used in solid electrolytic capacitors, where a porous metal anode and a thin tantalum pentoxide dielectric provide high capacitance per volume. It is also used in corrosion-resistant chemical equipment, heat exchangers, surgical implants, and high-temperature furnace parts. Tantalum carbide is important in hard materials, and tantalum additions improve some nickel- and cobalt-base superalloys. Because it absorbs little from body fluids and is corrosion resistant, the metal has had longstanding biomedical applications.
Tantalum is a strong, ductile metal that is nearly immune to chemical attack at room temperatures. It can be drawn into a fine wire that is used to evaporate metals, such as aluminum. It has a high melting point and is frequently used as a substitute for platinum, which is more expensive. Tantalum is used to make components for chemical plants, nuclear power plants, airplanes and missiles. Tantalum does not react with bodily fluids and is used to make surgical equipment. Tantalum also does not irritate the body and is used to make surgical sutures as well as implants, such as artificial joints and cranial plates. Tantalum is alloyed with steel to increase steel's ductility, strength and melting point.
Tantalum pentoxide (Ta2O5), one of tantalum's compounds, is a dielectric material and is used to make capacitors. It is also used to make a glass with a high index of refraction that is used in camera lenses. A composite consisting of tantalum carbide (TaC) and graphite is one of the hardest materials known and is used on the cutting edges of high-speed machine tools.
Scientists at Los Alamos have produced a tantalum carbide graphite composite material, which is said to be one of the hardest materials ever made. The compound has a melting point of 3738°C. Tantalum is used to make electrolytic capacitors and vacuum furnace parts, which account for about 60% of its use. The metal is also widely used to fabricate chemical process equipment, nuclear reactors, aircraft, and missile parts. Tantalum is completely immune to body liquids and is a nonirritating material. It has, therefore, found wide use in making surgical appliances. Tantalum oxide is used to make special glass with high index of refraction for camera lenses. The metal has many other uses.
Isotopes in Medicine
178 Ta (with a half-life of 9.3 min) is used in medical studies, such as first-pass radionuclide angiography of mice, to better understand cardiovascular disease. Radionuclide angiography uses a pinhole lens fitted to a high-speed multiwire proportional camera and a n(178W)/n(178Ta) amount-ratio generator for minimally invasive quantification of murine ventricular (heart) functions (Fig. IUPAC.73.1) [506] J. Lacy, T. Nanavaty, D. Dai, N. Nayak, N. Haynes, C. Martin. J. Nucl. Cardiol.8, 171 (2001)., [507] C. J. Hartley, G. E. Taffet, A. K. Reddy, M. L. Entman, L. H. Michael. ILAR J.43, 147 (2002).. The multiwire gamma camera has a 178Ta generator incorporated in its housing, and it provides portable and laboratory ventricular function assessments for cardiovascular patients [507] C. J. Hartley, G. E. Taffet, A. K. Reddy, M. L. Entman, L. H. Michael. ILAR J.43, 147 (2002)., [508] J. L. Lacy, A. D. LeBlanc, J. W. Babich, M. W. Bungo, L. A. Latson, R. M. Lewis, L. R. Poliner, R. H. Jones, P. C. Johnson. J. Nucl. Med.25, 1003 (1984).. Intravenous injections of 178Ta are used in gated equilibrium blood pool imaging [509] R. A. Wilson, S. Y. Kopiwoda, R. J. Callahan, R. H. Moore, C. A. Boucher, H. Manspeaker, F. P. Castronovo, H. W. Strauss. Eur. J. Nucl. Med. Mol. Imaging13, 82 (1987).. 183Ta (with a half-life of 5.1 days) has potential for use in radionuclide pharmaceuticals and as a tracer for toxicity studies of ecosystems [510] N. Shigeta, R. M. Lambrecht, H. Matsuoka, A. Osa, M. Koizumi, K. Kobayashi, M. Izumo, K. Hashimoto, T. Sekine. Appl. Radiat. Isot.47, 171 (1996)..
Isotopes Used as a Source of Radioactive Isotope(s)
181Ta is used to produce 178W, which decays to 178Ta via the reaction 181Ta (p, 4 n) 178W, which is followed by a subsequent electron capture decay reaction of 178W to finally yield 178Ta. 178Ta is important for medical studies as noted in Section 4.73.1.
Tantalum forms strongly oxophilic compounds and is most stable in the +5 oxidation state. Tantalum pentoxide, Ta₂O₅, is the most important oxide and forms the dielectric film used in capacitors. Tantalum pentachloride, TaCl₅, is a volatile chloride used in synthesis and deposition chemistry. Tantalates contain TaO₆ octahedra in many minerals and ceramic materials. Lower oxidation states exist in halides and cluster compounds, but they are less common in ordinary aqueous chemistry. Tantalum carbide, TaC, is an extremely hard refractory ceramic.
See more information at the Tantalum compound page.
Massive tantalum metal is generally of low chemical toxicity and is valued for biocompatibility, but fine powder can burn and should be treated as a combustible metal dust. Soluble tantalum compounds are uncommon but should not be assumed harmless. Processing hazards often come from associated acids, fluorides, chlorides, and fine particulates rather than from the bulk metal itself. Natural tantalum is only very weakly radioactive because of trace ¹⁸⁰ᵐTa.
Tantalum occurs in resistant oxide minerals and is not abundant in surface waters. Weathering can move small amounts in heavy-mineral sediments, while much remains in insoluble phases. It has no known essential biological role. Environmental concerns are usually linked to mining, mineral concentration, tailings, and the handling of associated elements rather than to high mobility of tantalum ions in natural waters.
Tantalum is produced mainly from tantalite- and columbite-bearing ores, from complex lithium-cesium-tantalum pegmatites, and as a by-product of tin or lithium mineral processing. Separation from niobium is a central refining step because the two elements have similar chemistry. Demand is strongly influenced by electronics, especially capacitors, but superalloys, carbides, and corrosion-resistant equipment also matter. Supply can be constrained by ore concentration, co-production relationships, conflict-mineral controls, and the need for specialized refining. Recycling from capacitor scrap and superalloy residues contributes but does not fully replace mined supply.
Tantalum ores are found in Australia, Brazil, Mozambique, Thailand, Portugal, Nigeria, Zaire, and Canada.
Tantalum is a rare heavy element in the cosmos. Its stable and long-lived isotopes are made mainly by neutron-capture processes in earlier generations of stars, with contributions from slow and rapid capture pathways. In planetary materials it is lithophile and refractory, so it concentrates in silicate reservoirs and resists volatilization during high-temperature condensation.
- Tantalum and niobium are so similar chemically that their separation shaped much of their early metallurgy.
- ¹⁸⁰ᵐTa is the rarest naturally occurring long-lived nuclear isomer known.
- The dielectric layer in tantalum capacitors is grown directly from the metal surface.
- Tantalum resists many acids but is attacked by hydrofluoric acid and fluoride-containing mixtures.
- Its name refers to Tantalus, reflecting the early difficulty of dissolving its oxide.
Images
Properties
Physical
- Atomic radius (empirical)
- 145 pm Compare Atomic radius (empirical) of all elements →
- Covalent radius
- 170 pm Compare Covalent radius of all elements →
- Van der Waals radius
- 217 pm Compare Van der Waals radius of all elements →
- Metallic radius
- 134 pm Compare Metallic radius of all elements →
- Density
- 1.64 × 104 kg/m³ Compare Density of all elements →
- Molar volume
- 0.0109 L/mol
- Phase at STP
- Solid Compare Phase at STP of all elements →
- Melting point
- 3016.85 °C Compare Melting point of all elements →
- Boiling point
- 5457.85 °C Compare Boiling point of all elements →
- Thermal conductivity
- 57.5 W/(m·K) Compare Thermal conductivity of all elements →
- Specific heat capacity
- 0.14 J/(g·K) Compare Specific heat capacity of all elements →
- Molar heat capacity
- 25.36 J/(mol·K) Compare Molar heat capacity of all elements →
- Crystal structure
- Body-centered cubic Compare Crystal structure of all elements →
Chemical
- Electronegativity (Pauling)
- 1.5 Compare Electronegativity (Pauling) of all elements →
- Electronegativity (Allen)
- 1.34
- Electron affinity
- 0.322 eV
- Ionization energy (1st)
- 7.549571 eV Compare Ionization energy (1st) of all elements →
- Ionization energy (2nd)
- 16.200056 eV Compare Ionization energy (2nd) of all elements →
- Ionization energy (3rd)
- 23.10008 eV Compare Ionization energy (3rd) of all elements →
- Ionization energy (4th)
- 35.00012 eV Compare Ionization energy (4th) of all elements →
- Ionization energy (5th)
- 48.272166 eV Compare Ionization energy (5th) of all elements →
- Oxidation states
- −3, −1, 0, +1, +2, +3, +4, +5 Compare Oxidation states of all elements →
- Valence electrons
- 5 Compare Valence electrons of all elements →
- Electron configuration
- [Xe] 6s2 4f14 5d3
Thermodynamic
- Heat of fusion
- 0.37902265 eV Compare Heat of fusion of all elements →
- Heat of vaporization
- 7.804322 eV Compare Heat of vaporization of all elements →
- Heat of sublimation
- 8.104887 eV
- Heat of atomization
- 8.104887 eV
- Atomization enthalpy
- 8.104887 eV
Nuclear
- Protons
- 73 Compare Protons of all elements →
- Neutrons
- 108 Compare Neutrons of all elements →
- Known isotopes
- 40 Compare Known isotopes of all elements →
- Stable isotopes
- 1 Compare Stable isotopes of all elements →
- Most stable isotope
- Ta-181
- Discovery year
- 1802
Abundance
- Abundance (Earth's crust)
- 2 mg/kg Compare Abundance (Earth's crust) of all elements →
- Abundance (ocean)
- 2 × 10−6 mg/L Compare Abundance (ocean) of all elements →
Crystal Structure
- Lattice constant a
- 331 pm
Electronic Structure
- Electrons per shell
- 2, 8, 18, 32, 11, 2 Compare Electrons per shell of all elements →
Identifiers
- CAS number
- 7440-25-7 Compare CAS number of all elements →
- Term symbol
- 4F3/2
- InChI
- InChI=1S/Ta
- InChI Key
- GUVRBAGPIYLISA-UHFFFAOYSA-N
Electron Configuration Measured
Ta: 4f¹⁴ 5d³ 6s²[Xe] 4f¹⁴ 5d³ 6s²1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁶ 4f¹⁴ 5d³ 6s²Atomic model
Isotopes change neutron count, mass, and stability — not the electron configuration of a neutral atom.
Schematic atomic model, not to scale.
Atomic Fingerprint
Emission / Absorption Spectrum
Isotope Distribution
| Mass number | Atomic mass (u) | Natural abundance | Half-life |
|---|---|---|---|
| 181 Stable | 180.9479958 ± 0.000002 | 99.9880% | Stable |
Phase / State
Reason: 2991.8 °C below melting point (3016.85 °C)
Schematic, not to scale
Phase transition points
Transition energies
Energy required to melt 1 mol at melting point
Energy required to vaporize 1 mol at boiling point
Energy required to sublime 1 mol at sublimation point
Density
At standard conditions
At standard conditions
Atomic Spectra
Showing 10 of 73. Sorted by ion charge (ascending).
Lines Holdings ?
| Ion | Charge | Total lines | Transition probabilities | Level designations |
|---|---|---|---|---|
| Ta I | 0 | 526 | 200 | 510 |
| Ta II | +1 | 141 | 0 | 13 |
| Ta IV | +3 | 83 | 0 | 0 |
| Ta V | +4 | 12 | 0 | 0 |
Levels Holdings ?
| Ion | Charge | Levels |
|---|---|---|
| Ta I | 0 | 301 |
| Ta II | +1 | 134 |
| Ta III | +2 | 2 |
| Ta IV | +3 | 2 |
| Ta V | +4 | 2 |
| Ta VI | +5 | 2 |
| Ta VII | +6 | 2 |
| Ta VIII | +7 | 2 |
| Ta IX | +8 | 2 |
| Ta X | +9 | 2 |
Ionic Radii
| Charge | Coordination | Spin | Radius |
|---|---|---|---|
| +3 | 6 | N/A | 72 pm |
| +4 | 6 | N/A | 68 pm |
| +5 | 6 | N/A | 64 pm |
| +5 | 7 | N/A | 69 pm |
| +5 | 8 | N/A | 74 pm |
Compounds
Isotopes (1)
| Mass number | Atomic mass (u) | Natural abundance | Half-life | Decay mode | |
|---|---|---|---|---|---|
| 181 Stable | 180.9479958 ± 0.000002 | 99.9880% ± 0.0003% | Stable | stable |
Extended Properties
Covalent Radii (Extended)
- Covalent radius (Pyykkö)
- 146 pm
- Covalent radius (Pyykkö, double)
- 126 pm
- Covalent radius (Pyykkö, triple)
- 119 pm
Van der Waals Radii
- Batsanov
- 220 pm
- Alvarez
- 253 pm
- UFF
- 317 pm
- MM3
- 243 pm
Atomic & Metallic Radii
- Atomic radius (Rahm)
- 258 pm
- Metallic radius (C12)
- 146 pm
Numbering Scales
- Mendeleev
- 49
- Pettifor
- 53
- Glawe
- 52
Electronegativity Scales
- Ghosh
- 0
- Miedema
- 4
- Gunnarsson–Lundqvist
- 5
- Robles–Bartolotti
- 4
Polarizability & Dispersion
- Dipole polarizability
- 74 a.u.
- Dipole polarizability (unc.)
- 20 a.u.
- C₆ (Gould–Bučko)
- 887 Ha·Bohr6
Miedema Parameters
- Miedema molar volume
- 10.81 cm3/mol
- Miedema electron density
- 4
Supply Risk & Economics
- Production concentration
- 25
- Relative supply risk
- 7
- Reserve distribution
- 54
- Political stability (top producer)
- 48
- Political stability (top reserve)
- 48
Phase Transitions & Allotropes
| Melting point | 3290.15 K |
| Boiling point | 5728.15 K |
Oxidation State Categories
Advanced Reference Data
Screening Constants (14)
| n | Orbital | σ |
|---|---|---|
| 1 | s | 1.4163 |
| 2 | p | 4.4136 |
| 2 | s | 19.0702 |
| 3 | d | 13.5589 |
| 3 | p | 21.1996 |
| 3 | s | 21.9085 |
| 4 | d | 36.676 |
| 4 | f | 39.5296 |
| 4 | p | 34.2652 |
| 4 | s | 33.2412 |
Crystal Radii Detail (5)
| Charge | CN | Spin | rcrystal (pm) | Origin |
|---|---|---|---|---|
| 3 | VI | 86 | estimated, | |
| 4 | VI | 82 | estimated, | |
| 5 | VI | 78 | ||
| 5 | VII | 83 | ||
| 5 | VIII | 88 |
Isotope Decay Modes (52)
| Isotope | Mode | Intensity |
|---|---|---|
| 155 | p | 100% |
| 156 | p | 71% |
| 156 | B+ | 29% |
| 157 | A | 96.6% |
| 157 | p | 3.4% |
| 157 | B+ | — |
| 158 | A | 100% |
| 158 | B+ | — |
| 159 | B+ | 66% |
| 159 | A | 34% |
X‑ray Scattering Factors (716)
| Energy (eV) | f₁ | f₂ |
|---|---|---|
| 10 | — | 3.16064 |
| 10.1152 | — | 3.23709 |
| 10.2317 | — | 3.31539 |
| 10.3496 | — | 3.39558 |
| 10.4688 | — | 3.47772 |
| 10.5894 | — | 3.56683 |
| 10.7114 | — | 3.65875 |
| 10.8348 | — | 3.75304 |
| 10.9596 | — | 3.84976 |
| 11.0859 | — | 3.94897 |
Additional Data
Estimated Crustal Abundance
The estimated element abundance in the earth's crust.
2.0 milligrams per kilogram
References (1)
- [5] Tantalum https://education.jlab.org/itselemental/ele073.html
Estimated Oceanic Abundance
The estimated element abundance in the earth's oceans.
2×10-6 milligrams per liter
References (1)
- [5] Tantalum https://education.jlab.org/itselemental/ele073.html
Sources
Sources of this element.
Tantalum ores are found in Australia, Brazil, Mozambique, Thailand, Portugal, Nigeria, Zaire, and Canada.
References (1)
- [6] Tantalum https://periodic.lanl.gov/73.shtml
Production
Production of this element (from raw materials or other compounds containing the element).
Separation of tantalum from niobium requires several complicated steps. Several methods are used to commercially produce the element, including electrolysis of molten potassium fluorotantalate, reduction of potassium fluorotantalate with sodium, or reacting tantalum carbide with tantalum oxide. Twenty five isotopes of tantalum are known to exist. Natural tantalum contains two isotopes.
References (1)
- [6] Tantalum https://periodic.lanl.gov/73.shtml
References
(9)
Data deposited in or computed by PubChem
The half-life and atomic mass data was provided by the Atomic Mass Data Center at the International Atomic Energy Agency.
Element data are cited from the Atomic weights of the elements (an IUPAC Technical Report). The IUPAC periodic table of elements can be found at https://iupac.org/what-we-do/periodic-table-of-elements/. Additional information can be found within IUPAC publication doi:10.1515/pac-2015-0703 Copyright © 2020 International Union of Pure and Applied Chemistry.
The information are cited from Pure Appl. Chem. 2018; 90(12): 1833-2092, https://doi.org/10.1515/pac-2015-0703.
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The periodic table at the LANL (Los Alamos National Laboratory) contains basic element information together with the history, source, properties, use, handling and more. The provenance data may be found from the link under the source name.
The periodic table contains NIST's critically-evaluated data on atomic properties of the elements. The provenance data that include data for atomic spectroscopy, X-ray and gamma ray, radiation dosimetry, nuclear physics, and condensed matter physics may be found from the link under the source name. Ref: https://www.nist.gov/pml/atomic-spectra-database
This section provides all form of data related to element Tantalum.
The element property data was retrieved from publications.