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7440-25-7

Name TANTALUM
CAS 7440-25-7
EINECS(EC#) 231-135-5
Molecular Formula Ta
MDL Number MFCD00011252
Molecular Weight 180.95
MOL File 7440-25-7.mol

Chemical Properties

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)

Safety Data

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

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