Chemical element · reference page

73Ta

Tantalum

Tantalum is element 73 (Ta), located in period 6, group 5 and the d block. At room temperature its reference phase is solid. Its electron configuration is [Xe] 4f14 5d3 6s2.

Atomic number73

Standard atomic weight180.94788(2)

Group5

Period6

Blockd

Electron configuration[Xe] 4f14 5d3 6s2

Electronic structure

What controls its chemistry

The d subshell participates in the chemistry of tantalum. Transition metals can use electrons of similar energies in bonding, which is why variable oxidation states, coordination compounds and catalytic behaviour are common across the d block.

Its electron configuration, [Xe] 4f14 5d3 6s2, should be read together with the oxidation state of the compound: removing electrons changes which d orbitals are occupied and can alter colour, magnetism, bonding and reactivity.

Chemical forms

Compounds, ions and materials

For tantalum, important chemical forms include metals and alloys, oxides, halides and coordination compounds. Variable oxidation states are common because s and d electrons have similar energies, and ligands around the metal ion can strongly alter colour, magnetism and reactivity.

Physical behaviour

State and phase changes

The reference phase at room temperature is solid. The listed density is 16.69 g/cm³. The melting point is 3 280 K (3 007 °C). The boiling point is 5 731 K (5 458 °C). Pressure, purity and crystal structure can shift measured physical properties.

Occurrence and applications

Where tantalum is found and used

In practice, tantalum is encountered in capacitors, implants and superalloys.

In practice

Examples of real uses

Capacitors

Tantalum is used in capacitor materials where high capacitance, stable oxide films or compact component design is valuable.

Implants

Tantalum is used in biomedical materials selected for corrosion resistance, strength and compatibility with the body.

Superalloys

Tantalum is used in alloys engineered to retain mechanical strength and resist oxidation at very high temperatures.

Periodic position

What its neighbours tell us

Tantalum is in period 6 and group 5. In the neighbourhood shown here, it lies between hafnium and tungsten in the same period; niobium is above it and dubnium below it in the same group. These positions make it possible to compare atomic size, ionisation energy and bonding behaviour with nearby elements.

Reference data

Physical and atomic properties

Classificationtransition metal

Phase at room temperatureSolid

Electron shells2 · 8 · 18 · 32 · 11 · 2

Density16.69 g/cm³

Melting point3 280 K (3 007 °C)

Boiling point5 731 K (5 458 °C)

Pauling electronegativity1.5

First ionisation energy728kJ/mol

Electron affinity31 kJ/mol

Values describe the element or neutral atom where applicable. Physical data can depend on allotrope, pressure and measurement conditions.

History

Discovery and identification

The discovery of tantalum is associated with Anders Gustaf Ekeberg. Recognition of the element, isolation of a pure sample and assignment of its modern atomic number did not necessarily occur at the same time.

Isotopes and atomic weight

How isotope composition changes the numbers

The standard atomic weight is 180.94788(2). This value refers to the isotopic composition of natural terrestrial material, not to the mass of one specific atom.

Tantalum has at least one stable isotope. Different isotopes have the same number of protons and therefore the same element identity, but different neutron numbers and atomic masses.

Safety

Handling and exposure

The hazards associated with tantalum depend on chemical form, dose and route of exposure. Pure tantalum, its ions and its compounds can have very different biological and environmental effects, so safety data should be checked for the actual substance being handled.