Tantalum

Tantalum, ₇₃Ta
Tantalum
Pronunciation	/ˈtæntələm/ (TAN-tə-ləm)
Appearance	gray blue
Standard atomic weight Ar, std(Ta)	180.94788(2)[1]
Tantalum in the periodic table
	hafnium ← tantalum → tungsten
Atomic number (Z)	73
Group	group 5
Period	period 6
Block	d-block
Electron configuration	[Xe] 4f14 5d3 6s2
Electrons per shell	2, 8, 18, 32, 11, 2
Physical properties
Phase at STP	solid
Melting point	3290 K (3017 °C, 5463 °F)
Boiling point	5731 K (5458 °C, 9856 °F)
Density (near r.t.)	16.69 g/cm3
when liquid (at m.p.)	15 g/cm3
Heat of fusion	36.57 kJ/mol
Heat of vaporization	753 kJ/mol
Molar heat capacity	25.36 J/(mol·K)
Atomic properties
Oxidation states	−3, −1, 0, +1, +2, +3, +4, +5 (a mildly acidic oxide)
Electronegativity	Pauling scale: 1.5
Ionization energies	1st: 761 kJ/mol ; 2nd: 1500 kJ/mol ; ;
Atomic radius	empirical: 146 pm
Covalent radius	170±8 pm
	Spectral lines of tantalum
Other properties
Natural occurrence	primordial
Crystal structure	body-centered cubic (bcc)[2] ; α-Ta
Crystal structure	tetragonal[2] ; β-Ta
Speed of sound thin rod	3400 m/s (at 20 °C)
Thermal expansion	6.3 µm/(m⋅K) (at 25 °C)
Thermal conductivity	57.5 W/(m⋅K)
Electrical resistivity	131 nΩ⋅m (at 20 °C)
Magnetic ordering	paramagnetic[3]
Molar magnetic susceptibility	+154.0·10−6 cm3/mol (293 K)[4]
Young's modulus	186 GPa
Shear modulus	69 GPa
Bulk modulus	200 GPa
Poisson ratio	0.34
Mohs hardness	6.5
Vickers hardness	870–1200 MPa
Brinell hardness	440–3430 MPa
CAS Number	7440-25-7
History
Discovery	Anders Gustaf Ekeberg (1802)
Recognized as a distinct element by	Heinrich Rose (1844)
Main isotopes of tantalum
β−	180W

Tantalum is a chemical element. Tantalum was named tantalium. It has the chemical symbol Ta. It has the atomic number 73. It is a rare metal. It is hard and blue-gray. In chemistry it is placed in a group of metal elements named the transition metals.

Tantalum in a glass tube

Tantalum does not easily corrode. It is found in the mineral tantalite.

Sources

"Standard Atomic Weights: Tantalum". CIAAW. 2005.
Moseley, P. T.; Seabrook, C. J. (1973). "The crystal structure of β-tantalum". Acta Crystallographica Section B Structural Crystallography and Crystal Chemistry. 29 (5): 1170–1171. doi:10.1107/S0567740873004140.
Lide, D. R., ed. (2005). "Magnetic susceptibility of the elements and inorganic compounds". CRC Handbook of Chemistry and Physics (PDF) (86th ed.). Boca Raton (FL): CRC Press. ISBN 0-8493-0486-5.
Weast, Robert (1984). CRC, Handbook of Chemistry and Physics. Boca Raton, Florida: Chemical Rubber Company Publishing. pp. E110. ISBN 0-8493-0464-4.

This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.

[1] "Standard Atomic Weights: Tantalum". CIAAW. 2005.

[crystal_structure-2] Moseley, P. T.; Seabrook, C. J. (1973). "The crystal structure of β-tantalum". Acta Crystallographica Section B Structural Crystallography and Crystal Chemistry. 29 (5): 1170–1171. doi:10.1107/S0567740873004140.

[magnet-3] Lide, D. R., ed. (2005). "Magnetic susceptibility of the elements and inorganic compounds". CRC Handbook of Chemistry and Physics (PDF) (86th ed.). Boca Raton (FL): CRC Press. ISBN 0-8493-0486-5.

[4] Weast, Robert (1984). CRC, Handbook of Chemistry and Physics. Boca Raton, Florida: Chemical Rubber Company Publishing. pp. E110. ISBN 0-8493-0464-4.