Tantalum

General
Name, Symbol, Number	Tantalum, Ta, 73
Chemical series	Transition metals
Group, Period, Block	5 (VB)[?], 6 , d
Density, Hardness	16650 kg/m3, 6.5
Appearance	gray blue
Atomic Properties
Atomic weight	180.9479 amu
Atomic radius (calc.)	145 (200) pm
Covalent radius	138 pm
van der Waals radius	no data
Electron configuration	[Xe]4f14 5d3 6s2
e- 's per energy level	2, 8, 18, 32, 11, 2
Oxidation state (Oxide)	5 (mildly acidic)
Crystal structure	Cubic body centered
Physical Properties
State of matter	solid
Melting point	3290 K (5463 °F)
Boiling point	5731 K (9856 °F)
Molar volume	10.85 ×10-3 m3/mol
Heat of vaporization	743 kJ/mol
Heat of fusion	31.6 kJ/mol
Vapor pressure	0.776 Pa at 3269 K
Speed of sound	3400 m/s at 293.15 K
Miscellaneous
Electronegativity	1.5 (Pauling scale)
Specific heat capacity	140 J/(kg*K)
Electrical conductivity	7.61 106/m ohm
Thermal conductivity	57.5 W/(m*K)
1st ionization potential	761 kJ/mol
2nd ionization potential	1500 kJ/mol
Most Stable/Notable Isotopes
iso NA half-life DM DE MeV DP 179Ta {syn.} 1.82 y ε 0.110 179Hf 180Ta 0.012% 8.125 h ε β+[?] 0.854 0.708 180Hf 180W Meta {Syn} >1.2 E15 y β- ε 0.075 180W 180Hf 181Ta 99.988% Ta is stable with 108 neutrons
SI units & STP are used except where noted.

Tantalum (formerly tantalium) is a chemical element in the periodic table that has the symbol Ta and atomic number 73. A rare, hard, blue-gray, lustrous, transition metal, tantalum is highly corrosion-resistant and occurs in the mineral tantalite[?]. Tantalum is used in surgical instruments and implants because it does not react with body fluids.

Table of contents 1 Notable Characteristics 2 Applications 3 History 4 Occurrence 5 Compounds 6 Isotopes 7 Precautions 8 External Links

Notable Characteristics Tantalum is gray, heavy, ductile, very hard, easily fabricated, highly resistant to corrosion by acids, and is a good conductor of heat and electricity. In fact, at temperatures below 150 °C tantalum is almost completely immune to chemical attack and can only be attacked by hydrofluoric acid[?], acidic solutions containing the fluoride ion, and free sulphur trioxide[?]. The element has a melting point exceeded only by tungsten and rhenium (melting point 3290 K, boiling point 5731 K). Applications The major use for tantalum, as tantalum metal powder, is in the production of electronic components, mainly tantalum capacitors. Major end uses for tantalum capacitors include portable telephones, pagers, personal computers, and automotive electronics.

Tantalum is also used to produce a variety of alloys that have high melting points, are strong and have good ductility. Alloyed with other metals, it is also used in making carbide tools for metalworking equipment and in the production of superalloys[?] for jet engine components, chemical process equipment, nuclear reactors, and missile parts. It is ductile and can be drawn into fine wire, which is used as a filament for evaporating metals such as aluminum.

Because it is totally immune to the action of body liquids and is nonirritating it is widely used in making surgical appliances. Tantalum oxide is to make special high index of refraction glass for camera lenses. The metal is also used to make vacuum furnace[?] parts. History Tantalum (Greek Tantalos, mythological character) was discovered in Sweden in 1802 by Anders Ekeberg[?] and isolated in 1820 by Jons Berzelius[?]. Many contemporary chemists believed niobium and tantalum were the same elements until 1844 and later 1866 when researchers showed that niobic and tantalic acids were different compounds. Early investigators were only able to isolate impure metal and the first relatively pure ductile metal was produced by Werner von Bolton[?] in 1903. Wires made with tantalum metal were used for light bulbs until tungsten replaced it.

Its name is derived from the character Tantalus, father of Niobe in Greek mythology, who was punished after death by being condemned to stand knee-deep in water with perfect fruit growing above his head, both of which eternally tantalized him - if he bent to drink the water, it drained below the level he could reach, and if he reached for the fruit, the branches moved out of his grasp. This was considered similar to tantalum's general non-reactivity - it sits among reagents and is unaffected by them. Occurrence Tantalum occurs principally in the mineral tantalite[?] [(Fe, Mn) Ta₂O₆] and euxenite (other minerals: samarskite[?], and fergusonite[?]).

Tantalum ores are mined in Australia, Brazil, Canada, the Democratic Republic of the Congo, Mozambique, Nigeria, Portugal, and Thailand.

Tantalite is largely found mixed with columbite in an ore called coltan, about whose sources ethical questions have been raised (see the article).

Several complicated steps are involved in the separation of tantalum from niobium. Commercially production of this element can follow one of several different methods which includes; electrolysis of molten potassium fluorotantalate, reduction of potassium fluorotantalate with sodium, or by reacting tantalum carbide with tantalum oxide. Tantalum is also a byproduct from tin extraction. Compounds Los Alamos National Laboratory scientists have made a tantalum carbide graphite composite[?] material that is one of the hardest materials made. Isotopes Natural tantalum consists of two isotopes. Ta-181 is a stable isotope, and Ta-180 is a radioactive isotope that quickly transforms into a nuclear isomer with a half life of over a 10¹⁵[?] years (1 with 15 zeros). Precautions Tantalum containing compounds are rarely encountered, and the metal does not normally cause problems in the laboratory, but it should still be regarded as highly toxic. There is some evidence that tantalum compounds can cause tumors, and its metal dust is a fire and explosion hazard.

External Links

• WebElements.com - Tantalum (http://www.webelements.com/webelements/elements/text/Ta/index)
• EnvironmentalChemistry.com - Tantalum (http://environmentalchemistry.com/yogi/periodic/Ta)