| Identification | More | [Name]
TANTALUM | [CAS]
7440-25-7 | [Synonyms]
Tantal
TA000090
TA000590
TA007320
TA007950
TA007055
TA007450
TA007100
TA000080
TA000140
TA007300
TA007800
TA000384
TA000260
TA000353
TA000585
TA007910
TA000411
TA007550
TA000490
TA005350
TA000352
TA000120
TA000290
TA007060
TA005150
TA000070
TA007948
TA000550
TA000110
TA007942
TA000482
TA007220
TA007050
TA007070
TA000580
TA004500
TA000452
TA000483
TANTALUM
TA000300
TA000357
TA000470
TA000280
TA000348
TA000285
TA007600
TA007350
TA000100
TA007917
TA007200
TA005130
TA000190
TA008710
TA000355
TA000460
TA006810
TA000520
TA000485
TA007530
TA000354
TA007945
TA000130
TA000349
TA007501
TA007095
TA000320
TA000450
TA007926
TA000586
TA000480
TA007920
TA000356
TA000410
TA007915
TA000360
TA005140
TA005120
TA000347
TA007935
TA007090
TA005100
TA005135
TA005160
TA005155
TA007940
TA007250
TA000424
TA007030
TA000472
TA000555
TA007930
TA006100
TA005110
TantalumRod
TantalumBar
TantalumWire
tantalumfoil
Tantalum-181
TantalumPlate
TantalumSheet
Tantalum slug
tantalum atom
Tantalum tube
TANTALUM METAL
Tantalum, Hard
TANTALUM TUBING
tantalumdioxide
TANTALUM 99.98%
TANTALUM POWDER
TANTALUM, 99.8%
Tantalum pellet
Tantalum Nanorods
Tantalum solution
Tantalumwiremmdia
TANTALUM STANDARD
Tantalum Thinfoil
Tantalum, Annealed
TANTALUM ALLOY ROD
TANTALUM NANOMETER
Tantalum foil (Ta)
TANTALUM CRUCIBLES
Tantalum foil500mm
Tantalum wires (Ta)
TANTALUM ALLOY FOIL
Tantalum pellet (Ta)
Tantalum powder (Ta)
TANTALUM AA STANDARD
TANTALUM ALLOY PLATE
TANTALUM METAL SHEET
TANTALUM ALLOY SHEET
Tantalum foil25x25mm
Tantalum foil50x50mm
Tantalum gauze75x75mm
Tantalum plate25x25mm
TANTALUM ICP STANDARD
TANTALUM ALLOY TUBING
Tantalum foil50x100mm
Tantalum foil50x500mm
Tantalum plate50x50mm
Tantalum rod (99.95%)
Tantalum wire (99.95%)
TantalumwireNmmdiacagm
TantalumrodNmmdiacagcm
Tantalum 99,5% , 99,9%
Tantalum foil150x200mm
Tantalum foil50x2000mm
Tantalum foil100x150mm
Tantalum foil (99.95%)
tantalum(metalandoxide
Tantalum foil150x500mm
Tantalum foil200x200mm
Tantalum foil100x100mm
Tantalum foil150x2000mm
Tantalum gauze150x150mm
TantaluM high-CV powder
TANTALUM POWDER 99+ 25 G
Tantalum, Powder 60 Mesh
TantalumpowderNppmNbmesh
Tantalum, Powder 325 Mesh
TANTALUM, POWDER, 99.99+%
Tantalum Pellets 6 x 6 mm
spherical tantalum powder
TantaluM Standard/TantaluM
Tantalum, pellets, 1/4x1/2
Tantalum, pellets, 1/4x1/4
TANTALUM, NANOPOWDER, 99+%
TantalumfoilNmmthickcagxmm
TANTALUM FINISHING PRODUCT
TANTALUM ROD 99.9% 5MM DIA
Tantalum, powder, -100 Mesh
TANTALUM ROD 99.9% 25MM DIA
TANTALUM ROD 99.9% 20MM DIA
TANTALUM ROD 99.9% 35MM DIA
TANTALUM ROD 99.9% 15MM DIA
TANTALUM ROD 99.9% 45MM DIA
Tantalum Wire 3 mm diameter
Tantalum Powder < 100 micron
Tantalum standard for AAS
Tantalum ISO 9001：2015 REACH
Tantalum Wire 0.5 mm diameter
Tantalum Wire 1.0 mm diameter
Tantalum Wire 2.0 mm diameter
Tantalum Wire 0.1 mm diameter
tantalum, metal tantalum foil
TANTALUM ROD (99.95%) 3MM DIA
Tantalum Wire 0.8 mm diameter
Tantalum Wire 1.5 mm diameter
Tantalum Wire 0.25 mm diameter
Tantalum wire (99.95%).5mm dia.
Tantalum, Powder 60 Mesh 99.98%
Tantalumpowder(99.98%,Nb-25ppm)
Tantalum(V) chloride solution
TANTALUM, AAS STANDARD SOLUTION
TANTALUM SINGLE ELEMENT STANDARD
tantalum(metalandoxidedust,asta)
Tantalum wire (99.95%).25mm dia.
TantaluM slug,6MM dia×6MM length.
TANTALUM: 99.995%, WIRE, 1MM DIA.
Tantalum Pellets 8-12 mm diameter
TANTALUM PLASMA EMISSION STANDARD
TANTALUM, PLASMA STANDARD SOLUTION
TANTALUM: 99.9%, WIRE, 0.25MM DIA.
TANTALUM: 99.9%, POWDER, 45 MICRON
TANTALUM, ROD, 3.2MM DIAM., 99.9+%
TANTALUM, POWDER, -325 MESH, 99.9%
TantaluM Metal, 1-5 Micron, Powder
Tantalum powder, 60-100 mesh, 99.9%
TANTALUM, FOIL, 0.5MM THICK, 99.9+%
TANTALUM, WIRE, 2.0MM DIAM., 99.9+%
TANTALUM, ROD, 6.35MM DIAM., 99.9+%
TANTALUM, FOIL, 1.0MM THICK, 99.9+%
Tantalum Rod 5 mm diameter x 100 mm
Tantalum Rod 10 mm diameter x 50 mm
TANTALUM ATOMIC ABSORPTION STANDARD
Tantalum rod, 6.4mm (0.25 in.) dia.
Tantalum wire, 0.7mm (0.03 in.) dia.
Tantalum rod, 4.75mm (0.19 in.) dia.
TANTALUM, FOIL, 0.25MM THICK, 99.9+%
TANTALUM WIRE 0.25MM DIAM. 99.9+%
TANTALUM, FOIL, 0.05MM THICK, 99.9+%
TANTALUM, WIRE, 0.127MM DIAM., 99.9+%
TANTALUM: 99.98%, POWDER, -200 MICRON
Tantalum foil, 2.0mm (0.08 in.) thick
Tantalum foil, 0.7mm (0.03 in.) thick
Tantalum foil, 1.5mm (0.06 in.) thick
Tantalum foil, 1.0mm (0.04 in.) thick
TANTALUM FOIL ASTM B 708, GRADE R05200
Tantalum plate, 6.35mm (0.25 in.) thick
TANTALUM SINGLE ELEMENT PLASMA STANDARD
Tantalum wire, 0.127mm (0.005 in.) dia.
Tantalum foil, 0.025mm (0.001 in.) thick
TANTALUM ICP STANDARD TRACEABLE TO SRM F
TANTALUM POWDER (99.98% NB-25PPM) -60MESH
TANTALUM POWDER (99.98% NB-25PPM) -325MESH
foil,0.127mm=0.005inthick,hard,metalsbasis
Tantalum powder, 99.95% trace metals basis
Tantalum powder, 99.99% trace metals basis
Tantalum AA Standard,1000 ppm in H2O tr. HF
Tantalum wire (99.95%) 1mm dia. (ca. 13g/m)
TANTALUM GRANULAR 99.99% (METALS BASIS) 5MM
TANTALUM WIRE 0.1MM DIA 99.9% (METALS BASIS)
TANTALUM ATOMIC ABSORPTION STANDARD SOLUTION
TANTALUM GRANULAR 99.99% (METALS BASIS) 2MM
TANTALUM GRANULAR 99.99% (METALS BASIS) 1MM
TANTALUM GRANULAR 99.99% (METALS BASIS) 3MM
TANTALUM TUBING 5MM DIA 99.9% (METALS BASIS)
TANTALUM TUBING 1MM DIA 99.9% (METALS BASIS)
Tantalum, AAS standard solution, Ta 1000μg/mL
TANTALUM TUBING 20MM DIA 99.9% (METALS BASIS)
TANTALUM ROD (99.95%) 1MM DIA (APPROX. 13G CM)
TANTALUM SINGLE CRYSTAL 99.995% (METALS BASIS)
TANTALUM PLATE, 6MM THICK 99.9% (METALS BASIS)
TANTALUM PLASMA EMISSION SPECTROSCOPY STANDARD
TANTALUM TUBING 30MM DIA 99.9% (METALS BASIS)
TANTALUM TUBING 10MM DIA 99.9% (METALS BASIS)
TANTALUM PLATE, 5MM THICK 99.9% (METALS BASIS)
Tantalum foil, 0.025mm (0.001 in.) thick, hard
Tantalum foil, 0.5mm (0.02 in.) thick, annealed
TANTALUM PLATE, 10MM THICK 99.9% (METALS BASIS)
TANTALUM TUBING 0.5MM DIA 99.9% (METALS BASIS)
Tantalum plasma standard solution, Ta 1000μg/mL
Tantalum standard solution, 1 mg/ml Ta in 5% HF
Tantalum plasma standard solution, Ta 10000μg/mL
Tantalum, wire, 1.0mm diam., 99.9+% metals basis
Tantalum, wire, 0.5mm diam., 99.9+% metals basis
TANTALUM PLATE, 7.5MM THICK 99.9% (METALS BASIS)
TANTALUM ROD (99.95%) 6.35MM DIA (APPROX. 5.1G CM)
Tantalum, foil, 0.025mm thick, 99.9+% metals basis
Tantalum foil, 0.127mm (0.005 in.) thick, annealed
Tantalum rod, 2.8mm dia., 99.95% trace metals basis
Tantalumdisc,99,95%,dia.38mmx3mmheight(+/-0,3mmall)
Tantalum pellet, 1mm (0.04 in.) dia. x 2mm (0.08in)
TANTALUM ROD (99.95%) 12.5MM DIA (APPROX. 20.4G CM)
Tantalum rod, 6.35mm dia., 99.95% trace metals basis
Tantalumfoil,0.25mm(0.01in)thick,99,95%,100mmx100mm,
TANTALUM TUBING 3MM OD 2.4MM ID 99.9% (METALS BASIS) | [EINECS(EC#)]
231-135-5 | [Molecular Formula]
Ta | [MDL Number]
MFCD00011252 | [Molecular Weight]
180.95 | [MOL File]
7440-25-7.mol |
| Chemical Properties | Back Directory | [Definition]
Element of atomic number 73 in group VB of the
periodic table, aw 180.9479, valences of 2, 3, 5; no
stable isotopes. | [Appearance]
solid | [Melting point ]
2996 °C(lit.)
| [Boiling point ]
5425 °C(lit.)
| [density ]
16.69 g/cm 3 (lit.) | [vapor pressure ]
<0.01 mm Hg ( 537.2 °C)
| [storage temp. ]
no restrictions. | [solubility ]
reacts with HF | [form ]
wire
| [color ]
Gray to silver | [Specific Gravity]
16.6 | [Stability:]
Stable. Powder is very flamable. | [Resistivity]
13.5 μΩ-cm, 20°C | [Water Solubility ]
very resistant to attack by acids except HF, resistant to alkali solutions [KIR83] | [Merck ]
13,9143 | [Exposure limits]
ACGIH: TWA 0.5 ppm(2.5 mg/m3); Ceiling 2 ppm (Skin)
OSHA: TWA 3 ppm
NIOSH: IDLH 30 ppm(250 mg/m3); TWA 3 ppm(2.5 mg/m3); Ceiling 6 ppm(5 mg/m3) | [InChIKey]
GUVRBAGPIYLISA-UHFFFAOYSA-N | [History]
Discovered in 1802
by Ekeberg, but many chemists thought niobium and tantalum
were identical elements until Rose, 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 (Fe, Mn)(Nb, Ta)2O6. Tantalum ores
are found in Australia, Brazil, Rwanda, Zimbabwe, Congo-
Kinshasa, Nigeria, and Canada. 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. Thirty-four isotopes and isomers
of tantalum are known to exist. Natural tantalum contains two
isotopes, one of which is radioactive with a very long half-life.
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.
Scientists at Los Alamos have produced a tantalum carbide
graphite composite material that is said to be one of the hardest
materials ever made. The compound has a melting point
of 3738°C. Tantalum has good “gettering” ability at high temperatures,
and tantalum oxide films are stable and have good
rectifying and dielectric properties. 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, and
aircraft and missile parts. Tantalum is completely immune
to body liquids and is a nonirritating metal. It has, therefore,
found wide use in making surgical appliances. Tantalum oxide
is used to make special glass with a high index of refraction
for camera lenses. The metal has many other uses. The price
of (99.9%) tantalum is about $2/g. | [LogP]
-1 at 20℃ | [CAS DataBase Reference]
7440-25-7(CAS DataBase Reference) | [EPA Substance Registry System]
Tantalum (7440-25-7) |
| Hazard Information | Back Directory | [Chemical Properties]
Tantalum is a refractory metal in Group V-B of the periodic table. The pure metal is ductile, steel-blue to gray solid or black, odorless powder. | [General Description]
Tantalum dust is a black odorless powder. Mp: 2996°C; bp: approx. 5250°C. Density: 16.65 g cm-3. Insoluble in water. Tantalum oxide dust is a white, microcrystalline powder Mp: 1800°C. Density: 7.6 g cm-3. Insoluble in water. The mixture is listed as a toxic inhalation hazard by OHSA. | [Hazard]
Dust or powder may be flammable. Toxic
by inhalation. | [First aid]
If this chemical gets into the eyes, remove any contact lenses at once and irrigate immediately for at least 15 minutes, occasionally lifting upper and lower lids. Seek medical attention immediately. If this chemical contacts the skin, remove contaminated clothing and wash immediately with soap and water. Seek medical attention immediately. If this chemical has been inhaled, remove from exposure,begin rescue breathing (using universal precautions, including resuscitation mask) if breathing has stopped and CPR if heart action has stopped. Transfer promptly to a medical facility. When this chemical has been swallowed, get medical attention. Give large quantities of water and induce vomiting. Do not make an unconscious person vomit. | [Shipping]
UN3089 Metal powders, flammable, n.o.s., Hazard Class: 4.1; Labels: 4.1-Flammable solid. | [Incompatibilities]
A flammable solid; the dry powder can ignite spontaneously in air. Incompatible with lead chromate. A strong reducing agent; incompatible with oxidizers (chlorates, nitrates, peroxides, permanganates, perchlorates, chlorine, bromine, bromine trifluoride, fluorine, etc.); contact may cause fires or explosions. Keep away from alkaline materials, strong bases, strong acids, oxoacids, epoxides. Tantalum metal is attacked by hydrogen fluoride, fused alkalis, fuming sulfuric acid. | [Waste Disposal]
Sanitary landfill if necessary; recover if possible because of economic value. Technology exists for tantalum recovery from spent catalysts, for example. | [Physical properties]
Tantalum has properties similar to niobium and vanadium above it in group 5. It is a veryhard and heavy metal with a bluish color when in its rough state, but if polished, it has a silveryshine. It is ductile, meaning it can be drawn into fine wires, and also malleable, meaningit can be hammered and worked into shapes. Thin strips and wires of tantalum will ignite inair if exposed to a flame.
Tantalum’s melting point is 2,996°C, which is almost as high as tungsten and rhenium. Itboiling point is 5,425°C, and its density is 19.3 g/cm3. | [Isotopes]
There are 49 isotopes of tantalum. Only the isotope Ta-181 is stable andaccounts for 99.988% of the total mass of the element on Earth. Just 0.012% of the element’s mass is contributed by Ta-180, which has a half-life of 1.2×10+15 years and isthus considered naturally stable. The remaining 47 isotopes are all artificially producedin nuclear reactions or particle accelerators and have half-lives ranging from a few microsecondsto few days to about two years. | [Origin of Name]
Tantalum was named after Tantalus, who was the father of Niobe, the
queen of Thebes, a city in Greek mythology. (Note: The element tantalum was originally
confused with the element nobelium.) | [Occurrence]
Tantalum is the 51st most abundant element found on Earth. Although it is found in afree state, it is usually mixed with other minerals and is obtained by heating tantalum potassiumfluoride or by the electrolysis of melted salts of tantalum. Tantalum is mainly obtainedfrom the following ores and 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]. Tantalum’s oresare mined in South America, Thailand, Malaysia, Africa, Spain, and Canada. The UnitedStates has a few small native deposits but imports most of the tantalum it uses.
Since tantalum and niobium are so similar chemically, a solvent process must be employedto separate them from the common ores. They are dissolved in a solvent, resulting in 98% pure niobium oxide being extracted during this part of the process. This is followed by 99.5%pure tantalum oxide being extracted in a second solvent process. | [Characteristics]
Tantalum is almost as chemically inert at room temperatures (it has the ability to resistchemical attacks, including hydrofluoric acid) as are platinum and gold. It is often substitutedfor the more expensive metal platinum, and its inertness makes it suitable for constructingdental and surgical instruments and artificial joints in the human body. | [Production Methods]
It was identi?ed that tantalum minerals exists in over 70 differentchemicalcompositions.Thoseofgreatesteconomic importance are tantalite, microlite, and wodginite; however, it is common practice to name any tantalum-containing mineral concentrate as “tantalite”. Tantalum resources are widespread, with the most important known resources being found in Brazil and Australia. In mid-2008, the main mining operations were in Australia, Brazil,Canada,Mozambique,andEthiopiaandinmid-2009, in Brazil, Ethiopia, and China, with additional quantities originating in central Africa, Russia, and Southeast Asia. There is continued interest in exploration of this element in other countries, primarily in Egypt, Canada, Mozambique, and Saudi Arabia.
The major world mine producers of tantalum in 2010 were Brazil (180 tons), Mozambique (110 tons), Rwanda (100 tons), and Australia (80 tons). Other countries produced around 170 tons, so the total world production of tantalum was approximately 670 tons. The major producers of tantalum mineral concentrates are Australia, Brazil, and Canada. | [Production Methods]
The first successful industrial process used to extract tantalum and niobium from the tantalite-columbite-containing minerals employed alkali fusion to decompose the ore, acid treatment to remove most of the impurities, and the historic Marignac fractional-crystallization method to separate the tantalum from the niobium and to purify the resulting K2TaF7. Most tantalum production now employs recovery of the tantalum and niobium values by dissolution of the ore or ore concentrate in hydrofluoric acid. Then the dissolved tantalum and niobium values are selectively stripped from the appropriately acidified aqueous solution and separated from each other in a liquid-liquid extraction process using methyl isobutyl ketone (MIBK) or other suitable organic solvent. The resulting purified tantalum-bearing solution is generally treated with potassium fluoride or hydroxide to recover the tantalum in the form of potassium tantalum fluoride, K2TaF7, or with ammonium hydroxide to precipitate tantalum hydroxide, which is subsequently calcined to obtain tantalum pentoxide, Ta2O5. Tantalum metal is generally obtained by sodium reduction of K2TaF7, although electrolysis of K2TaF7 and carbon reduction of Ta2O5 in an electric furnace have also been used. Tantalum metal can absorb large volumes of hydrogen during heating in a hydrogenbearing atmosphere at an intermediate temperature range (450–700 °C (842-1,292 °F)). The hydrogen is readily removed by heating in vacuum at higher temperatures. | [Health Hazard]
Tantalum has a low order of toxicity
but has produced transient inflammatory
lesions in the lungs of animals.
Surgical implantation of tantalum metal
products such as plates and screws has not
shown any adverse tissue reaction, thus demonstrating
its physiological inertness. | [Flammability and Explosibility]
Flammable | [Carcinogenicity]
Although Oppenheimer et al., using embedded metal foil technique, have elicited two malignant ?brosarcomas in 50 embeddings of tantalum metal in 25Wistar rats aftera latent period of714days, these results remain a controversial issue. Miller et al. have studied tumorigenic transforming potential of tungsten, iron, nickel, and cobalt with tantalum as a comparison on an immortalized nontumorigenic human osteoblast-like cell line. No tumorigenic activity of Ta was reported, but data are not shown.
In the recent study, intramuscularly pellets (1mm 2mm cylinders) of weapons-grade WA were implantedtosimulateshrapnelwounds.Ratswereimplanted with 4 (low dose) or 20 pellets (high dose) of WA. Tantalum (20 pellets) and nickel (20 pellets) served as negative and positive controls, respectively. Rats implanted with tantalum (n=46) did not develop tumors. |
| Safety Data | Back Directory | [Hazard Codes ]
F,Xi,Xn | [Risk Statements ]
R11:Highly Flammable.
R36/37/38:Irritating to eyes, respiratory system and skin .
R20/21/22:Harmful by inhalation, in contact with skin and if swallowed . | [Safety Statements ]
S16:Keep away from sources of ignition-No smoking .
S26:In case of contact with eyes, rinse immediately with plenty of water and seek medical advice .
S33:Take precautionary measures against static discharges .
S36/37/39:Wear suitable protective clothing, gloves and eye/face protection .
S36:Wear suitable protective clothing . | [RIDADR ]
UN 3089 4.1/PG 2
| [WGK Germany ]
-
| [RTECS ]
WW5505000
| [Autoignition Temperature]
572 °F | [TSCA ]
Yes | [HazardClass ]
4.1 | [PackingGroup ]
II | [HS Code ]
8103909000 | [Safety Profile]
An inhalation hazard. Some industrial skin injuries from tantalum have been reported. Systemic industrial poisoning, however, is apparently unknown. Questionable carcinogen with experimental tumorigenic data. The dry powder iptes spontaneously in air. Incompatible with bromine trifluoride, fluorine, lead chromate. See also specific tantalum compounds. | [Hazardous Substances Data]
7440-25-7(Hazardous Substances Data) | [IDLA]
2,500 mg Ta/m3 |
| Questions And Answer | Back Directory | [Chemical Properties]
Tantalum is a blue-gray, ductile metal. It is highly resistant to corrosion though corrosion resistance to strong acids and atmospheric oxygen decreases at increasing temperatures. It is incompatible with strong oxidizers and alkalis.
| [History]
Tantalum was discovered by the Swedish chemist Anders Ekeberg in 1802, although for a long time after his discovery many chemists believed tantalum and niobium were the same element. In 1866, Marignac developed a fractional crystallization method for separation of tantalum from niobium. Ekeberg named the element in honor of Tantalus, who was Niobe’s father in Greek mythology.
Tantalum is never found in nature in free elemental form. The most important mineral is columbite-tantalite (Fe,Mn) (Nb,Ta)2O6. Tantalum also is found in minor quantities in minerals pyrochlore, samarskite, euexenite, and fergusonite. The abundance of tantalum in the earth’s crust is estimated as 2 mg/kg.
Tantalum and its alloys have high melting points, high strength and ductility and show excellent resistance to chemical attack. Tantalum carbide graphite composite is one of the hardest substances ever made and has a melting point over 6,700°C. The pure metal is ductile and can be drawn into fine wire, which is used as filament for evaporating aluminum and other metals.
| [Uses]
Tantalum filaments were used in incandescent lamp bulbs before tungsten replaced them. At temperatures below 150°C, tantalum is attacked only by hydrofluoric acid, fluoride ion in acidic solutions, and free sulfur trioxide. It also is attacked, but slowly, by alkalies. Tantalum and its alloys, therefore, are used to build reactors, vessels, and cruicibles for preparing and carrying out reactions involving many reactive intermediates. The metal and its alloys are used to construct furnace parts, electrolytic capacitors, aircraft and missile parts, chemical process equipment, and nuclear reactors. Being nonreactive to body fluids and a nonirritant to body tissues, tantalum is used in making surgical appliances. Plate and sheet tantalum are applied in bone repair, foil and wire for nerve repair, and plate, gauge, and sheet for repair of abdominal muscle. Tantalum oxide is used to produce optical glasses of high refractive index. The oxide film on the metal makes it a rectifier for converting alternating current to direct current.
| [Reactions]
The most common oxidation state of tantalum is +5 and its aqueous solution chemistry is that of its pentavalent ion Ta5+. Ta metal forms a pentavalent oxide, tantalum pentoxide, Ta2O5, on heating with oxygen. However, at ordinary temperatures a thin layer of oxide covering the metal surface protects tantalum from most chemical attacks. The metal is attacked by hydrofluoric acid below 150°C. It also is dissolved by hot fuming sulfuric acid. It reacts with fluorine and chlorine on heating, forming tantalum pentafluoride, TaF5, and pentachloride, TaCl5, respectively. The metal is immune to dilute aqueous alkalies but is attacked slowly by concentrated fused alkalies. It combines with molecular hydrogen above 250°C. The hydride formed decomposes on heating above 800°C in vacuum. Tantalum forms alloys with several metals.
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