Tantalum

180.9

The chemical element tantalum is classed as a transition metal. It was discovered in 1802 by Anders G. Ekeberg.

Data Zone

Classification:	Tantalum is a transition metal
Color:	gray
Atomic weight:	180.947
State:	solid
Melting point:	3020 ^oC, 3293 K
Boiling point:	5560 ^oC, 5833 K
Electrons:	73
Protons:	73
Neutrons in most abundant isotope:	108
Shells:	2,8,18,32,11,2
Electron configuration:	[Xe] 4f¹⁴ 5d³ 6s²
Density @ 20^oC:	16.6 g/cm³

Show more, including: Heats, Energies, Oxidation,
Reactions, Compounds, Radii, Conductivities

Atomic volume:	10.90 cm³/mol
Structure:	bcc: body-centered cubic
Hardness:	6.5 mohs
Specific heat capacity	0.14 J g^-1 K^-1
Heat of fusion	36.57 kJ mol^-1
Heat of atomization	782 kJ mol^-1
Heat of vaporization	737 kJ mol^-1
1^st ionization energy	761 kJ mol^-1
2^nd ionization energy	1500 kJ mol^-1
3^rd ionization energy	–
Electron affinity	31.1 kJ mol^-1
Minimum oxidation number	-1
Min. common oxidation no.	0
Maximum oxidation number	5
Max. common oxidation no.	5
Electronegativity (Pauling Scale)	1.5
Polarizability volume	13.1 Å³
Reaction with air	none
Reaction with 15 M HNO₃	none
Reaction with 6 M HCl	none
Reaction with 6 M NaOH	none
Oxide(s)	TaO₂, Ta₂O₅
Hydride(s)	Ta₂H
Chloride(s)	TaCl₃, TaCl₄, TaCl₅
Atomic radius	146 pm
Ionic radius (1+ ion)	–
Ionic radius (2+ ion)	–
Ionic radius (3+ ion)	86 pm
Ionic radius (1- ion)	–
Ionic radius (2- ion)	–
Ionic radius (3- ion)	–
Thermal conductivity	57.5 W m^-1 K^-1
Electrical conductivity	8.1 x 10⁶ S m^-1
Freezing/Melting point:	3020 ^oC, 3293 K

High purity tantalum. Photo by Tomihahndorf.

Tantalum capacitors

Discovery of Tantalum

Author: Dr. Doug Stewart

Tantalum was discovered by Anders G. Ekeberg in 1802, in Uppsala, Sweden, in the minerals tantalite from Finland and yttrotantalite from Sweden.

Unfortunately for Ekeberg, in 1809 the well-known English chemist Willian Wollaston said there had been no discovery and there was no new element.

Wollaston claimed Ekeberg’s new element was actually niobium, which had also been discovered in 1802. The scientific community came to believe Wollaston was right and that Ekeberg’s claim for a new element had been a mistake.

Tantalum and niobium are in fact hard to separate from one another, which led to Wollaston’s error.

In 1846 German mineralogist Heinrich Rose finally proved beyond doubt that tantalum and niobium were different elements.

In 1903 Werner von Bolton refined tantalum metal for the first time.

The element name comes from the Greek mythological character Tantalos. Niobe (niobium) was the daughter of Tantalos. Ekeberg gave his new element the name tantalum because it had been a tantalizing element to find.

Appearance and Characteristics

Harmful effects:

Tantalum is considered to be non-toxic.

Characteristics:

Tantalum is a rare, shiny, gray, dense metal. It is highly ductile and can be drawn into a thin wire.

Its chemical properties are very similar to those of niobium. Tantalum is highly corrosion resistant due to the formation of an oxide film. It is an excellent conductor of heat and electricity.

The metal has a melting point exceeded only by tungsten and rhenium. Tantalum is one of the five major refractory metals (metals with very high resistance to heat and wear). The other refractory metals are tungsten, molybdenum, rhenium and niobium.

Uses of Tantalum

Tantalum is used in the electronics industry for capacitors and high power resistors.

It is also used to make alloys to increase strength, ductility and corrosion resistance.

The metal is used in dental and surgical instruments and implants, as it causes no immune response.

Abundance and Isotopes

Abundance earth’s crust: 1.7 parts per million by weight, 0.2 parts per million by moles

Abundance solar system:

Cost, pure: $450 per 100g

Cost, bulk: $8.10 per 100g

Source: Tantalum is not found free in nature but in minerals such as columbite and tantalite. Minerals that contain tantalum often also contain niobium. Commercially, tantalum is extracted by first forming the oxide (Ta₂O₅). The oxide is then reduced using carbon or hydrogen.

Isotopes: Tantalum has 31 isotopes whose half-lives are known, with mass numbers from 156 to 186. Naturally occurring tantalum consists of its one stable isotope, ¹⁸¹Ta.

References

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