ChemSphere
73Ta180.948

Tantalum

Transition metal · Period 6 · Group 5 · d-block

The acid-proof metal inside nearly every smartphone

Atomic mass
180.948 u
State at 25 °C
Solid
Electronegativity
1.5
Melting point
3,016.9 °C
Boiling point
5,457.9 °C
Configuration
[Xe] 4f14 5d3 6s2
Building atom…
73 protons 108 neutrons 73 electrons

Nucleus drawn at reduced count for clarity. Drag to rotate.

Tantalum, explained

Video lesson in production

Bhavya’s explainer for this element will play here.

Overview

Tantalum is a dense, blue-grey group 5 metal with the configuration [Xe]4f14 5d3 6s2. Its five valence electrons form strong metallic bonds, giving it a melting point of 3017 °C. Its most valuable property is resistance to corrosion. Exposed to air, it instantly grows a thin, tightly adherent film of tantalum pentoxide, Ta2O5, which protects the metal from almost all acids, even aqua regia below 150 °C. Only hydrofluoric acid, fluoride-containing solutions, fuming sulfuric acid and hot strong alkalis attack it.

That oxide film is also the secret of tantalum capacitors. By growing the oxide electrochemically on porous tantalum powder, manufacturers create an extremely thin, uniform insulating layer with a high dielectric constant over a huge surface area, storing a large charge in a tiny volume. Because the metal is inert in the body, tantalum is also used for surgical implants and bone repair. Tantalum's chemistry is nearly identical to that of niobium above it, again because of the lanthanide contraction.

Discovery

Swedish chemist Anders Gustaf Ekeberg discovered tantalum in 1802 in minerals from Finland and Sweden. He named it after Tantalus, the figure in Greek myth condemned to stand in water he could never drink, because the oxide 'could not drink' acid even when immersed in it. For decades it was thought identical to columbium (niobium); Heinrich Rose and then Jean Charles Galissard de Marignac proved in the 1840s–1860s that they were separate elements.

Where it’s found
About 2 parts per million of Earth's crust, mined mainly from tantalite and coltan in Central Africa, Brazil and Australia.
What it’s used for
  • Electronic capacitors
  • Surgical implants
  • Chemical plant equipment
  • Jet-engine superalloys
  • Sputtering targets for chips
In living things
No biological role; tantalum is non-toxic and biocompatible, which is why it is used in implants.
Safety
The metal is safe to handle; fine powder is flammable.

How it compares

Where Tantalum sits among all 118 elements on the trends that shape the table.

  • Electronegativity1.5Pauling

    #55 of 100 elements with data

  • Ionization energy761kJ/mol

    #37 of 104 elements with data

  • Atomic radius145pm

    #46 of 95 elements with data

  • Electron affinity31kJ/mol

    #70 of 109 elements with data

  • Density16.7g/cm³

    #18 of 114 elements with data

  • Melting point3,290K

    #5 of 110 elements with data

Density
16.7 g/cm³
Atomic radius
145 pm
Covalent radius
146 pm
Molar heat
25.36 J/(mol·K)
Appearance
gray blue
Discovered by
Anders Gustaf Ekeberg

Inside the atom

73 electrons arranged in 6 shells: 2 · 8 · 18 · 32 · 11 · 2.

Orbital diagram

1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d3 · shorthand [Xe] 4f14 5d3 6s2

  1. 1s2
  2. 2s2
  3. 2p6
  4. 3s2
  5. 3p6
  6. 4s2
  7. 3d10
  8. 4p6
  9. 5s2
  10. 4d10
  11. 5p6
  12. 6s2
  13. 4f14
  14. 5d3

Each box is an orbital holding up to two electrons of opposite spin. Highlighted subshells hold the valence electrons that decide how Tantalum bonds.

Ionization energies

Energy to remove each electron in turn, on a log scale. Each electron is harder to remove than the last, because the remaining ones feel more of the nucleus.

Signature reactions

The chemistry Tantalum is known for.

  1. Redox · Combustion

    Oxidation to tantalum pentoxide

    Tantalum oxidises to the white pentoxide. At room temperature this oxide forms only a thin protective film, but grown deliberately it becomes the dielectric of a tantalum capacitor.

    4Ta(s)+5O2(g)2Ta2O5(s)

    Conditions: heating in air above about 300 °C

  2. Acid–base · Complex formation

    Attack by hydrofluoric acid

    Fluoride ions are among the few species that can break up tantalum oxide, forming the soluble heptafluorotantalate complex. Ore processing begins with this step.

    Ta2O5(s)+14HF(aq)2H2TaF7(aq)+5H2O(l)

    Conditions: concentrated HF

  3. Redox · Metal extraction

    Sodium reduction

    Molten sodium reduces potassium heptafluorotantalate to tantalum powder. Controlling the conditions sets the powder's grain size, which determines how much charge capacitors made from it can store.

    K2TaF7(l)+5Na(l)Ta(s)+2KF(l)+5NaF(l)

    Conditions: about 800 °C, molten salt

Where you’ll meet it

  • Tantalum capacitor

    Tantalum capacitor

    These compact components store charge across an ultra-thin film of tantalum oxide grown on porous tantalum.

    Photo: Wikimedia Commons
  • Coltan

    Coltan

    This ore, a mixture of columbite and tantalite, is the main source of tantalum.

    Photo: Wikimedia Commons
  • Tantalus

    Tantalus

    Tantalum is named after this mythical figure who could never drink the water around him.

    Photo: Wikimedia Commons
  • Smartphone

    Smartphone

    Phones and laptops contain tantalum capacitors that save space on crowded circuit boards.

    Photo: Wikimedia Commons

Research

No research on Tantalum yet

When Bhavya publishes a project that studies Tantalum, it will be linked here.

See all research