TANTALIO

introduzione

Numero atomico: 73
Gruppo: 5 or V B
Peso atomico: 180.9479
Periodo: 6
Numero CAS: 7440-25-7

Classificazione

Metallo
Metalloide
simile a metallo
metallo alcalino
Alkali terroso
Metallo di transizione
calcogeno
alogena
Gas nobile
Lanthanoid
Actinoid
Terre rare
Platinum Metal Group
transuranici
Non ci sono isotopi stabili
Solido
Liquido
Gas
Solido (previsto)

Descrizione • Usi / Funzione

Discovered in 1802 by Ekeberg, but many chemists thought niobium and tantalum were identical elements until Rose,in 1844, and Marignac, in1866, 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, Mozambique, Thailand, Portugal, Nigeria, Zaire, and Canada. Separation of tantalumfrom niobium requires several complicated steps. Several methods are used to commercially produce the element, including electrolysis of moltenpotassium fluorotantalate, reduction of potassium fluorotantalate with sodium, or reacting tantalum carbide with tantalum oxide. Thirty four isotopesand isomers of tantalum are known to exist. Natural tantalum contains two isotopes, one of which is radioactive with a very long half-life. Tantalumis 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 suchas aluminum. Tantalum is almost completely immune to chemical attack at temperatures below 150°C, and is attacked only by hydrofluoric acid, acidicsolutions 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 suchas high melting point, high strength, good ductility, etc. Scientists at Los Alamos have produced a tantalum carbide graphite composite material, whichis 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 hightemperatures, and tantalum oxide films are stable and have good rectifying and dielectric properties. Tantalum is used to make electrolytic capacitorsand vacuum furnace parts, which account for about 60% of its use. The metal is also widely used to fabricate chemical process equipment, nuclearreactors, and aircraft and missile parts. Tantalum is completely immune to body liquids and is a nonirritating metal. It has, therefore, found wide usein making surgical appliances. Tantalum oxide is used to make special glass with high index of refraction for camera lenses. The metal has many otheruses. The price of (99.9%) tantalum is about $900/kg. The metal of 99.995% purity sells for about $2/g. 1

• "A number of transition metals (Ti, Zr, Hf, V, Nb, Ta, Mo, W) form interstitial carbides of composition MC and, in some cases, M2C. These carbides have extremely high melting points; they are very hard, and they are good electrical conductors." 2

Proprietà fisiche

Punto di fusione:3*  3017 °C = 3290.15 K = 5462.6 °F
Punto di ebollizione:3* 5458 °C = 5731.15 K = 9856.4 °F
sublimazione Point:3 
Triple Point:3 
Punto critico:3 
Densità:4  16.4 g/cm3

* - at 1 atm

configurazione elettronica

configurazione elettronica: [Xe] 6s2 4f14 5d3
Bloccare: d
Più alto livello di energia Occupato: 6
Elettroni di valenza: 

numeri quantici:

n = 5
ℓ = 2
m = 0
ms = +½

bonding

elettronegatività (scala Pauling):5 1.5
Electropositivity (scala Pauling): 2.5
Affinità elettronica:6 0.322 eV
ossidazione Uniti: +5
Funzione di lavoro:7 4.22 eV = 6.76044E-19 J

potenziale di ionizzazione   eV 8  kJ/mol  
potenziale di ionizzazione   eV 8  kJ/mol  
potenziale di ionizzazione   eV 8  kJ/mol  
1 7.5496    728.4

Termochimica

Calore specifico: 0.140 J/g°C 9 = 25.333 J/mol°C = 0.033 cal/g°C = 6.055 cal/mol°C
Conduttività termica: 57.5 (W/m)/K, 27°C 10
Calore di fusione: 31.6 kJ/mol 11 = 174.6 J/g
Calore di vaporizzazione: 743 kJ/mol 12 = 4106.2 J/g
Stato della materia Entalpia di formazione (ΔHf°)13 entropia (S°)13 Energia libera di Gibbs (ΔGf°)13
(kcal/mol) (kJ/mol) (cal/K) (J/K) (kcal/mol) (kJ/mol)
(s) 0 0 9.92 41.50528 0 0
(g) 186.9 781.9896 44.241 185.104344 176.7 739.3128

isotopi

nuclide Massa 14 Metà vita 14 spin nucleare 14 Energia di legame
155Ta 154.97459(54)# 13(4) μs [12(+4-3) μs] (11/2-) 1,221.89 MeV
156Ta 155.97230(43)# 144(24) ms (2-) 1,229.96 MeV
157Ta 156.96819(22) 10.1(4) ms 1/2+ 1,247.34 MeV
158Ta 157.96670(22)# 49(8) ms (2-) 1,255.41 MeV
159Ta 158.963018(22) 1.04(9) s (1/2+) 1,263.49 MeV
160Ta 159.96149(10) 1.70(20) s (2#)- 1,271.56 MeV
161Ta 160.95842(6)# 3# s 1/2+# 1,288.94 MeV
162Ta 161.95729(6) 3.57(12) s 3+# 1,297.01 MeV
163Ta 162.95433(4) 10.6(18) s 1/2+# 1,305.09 MeV
164Ta 163.95353(3) 14.2(3) s (3+) 1,313.16 MeV
165Ta 164.950773(19) 31.0(15) s 5/2-# 1,321.23 MeV
166Ta 165.95051(3) 34.4(5) s (2)+ 1,329.30 MeV
167Ta 166.94809(3) 1.33(7) min (3/2+) 1,346.69 MeV
168Ta 167.94805(3) 2.0(1) min (2-,3+) 1,354.76 MeV
169Ta 168.94601(3) 4.9(4) min (5/2+) 1,362.83 MeV
170Ta 169.94618(3) 6.76(6) min (3)(+#) 1,370.90 MeV
171Ta 170.94448(3) 23.3(3) min (5/2-) 1,378.97 MeV
172Ta 171.94490(3) 36.8(3) min (3+) 1,387.04 MeV
173Ta 172.94375(3) 3.14(13) h 5/2- 1,395.11 MeV
174Ta 173.94445(3) 1.14(8) h 3+ 1,403.19 MeV
175Ta 174.94374(3) 10.5(2) h 7/2+ 1,411.26 MeV
176Ta 175.94486(3) 8.09(5) h (1)- 1,419.33 MeV
177Ta 176.944472(4) 56.56(6) h 7/2+ 1,427.40 MeV
178Ta 177.945778(16) 9.31(3) min 1+ 1,435.47 MeV
179Ta 178.9459295(23) 1.82(3) a 7/2+ 1,443.54 MeV
180Ta 179.9474648(24) 8.152(6) h 1+ 1,451.61 MeV
181Ta 180.9479958(19) STABILE 7/2+ 1,459.68 MeV
182Ta 181.9501518(19) 114.43(3) d 3- 1,458.44 MeV
183Ta 182.9513726(19) 5.1(1) d 7/2+ 1,466.51 MeV
184Ta 183.954008(28) 8.7(1) h (5-) 1,474.58 MeV
185Ta 184.955559(15) 49.4(15) min (7/2+)# 1,482.65 MeV
186Ta 185.95855(6) 10.5(3) min (2-,3-) 1,490.73 MeV
187Ta 186.96053(21)# 2# min [>300 ns] 7/2+# 1,489.48 MeV
188Ta 187.96370(21)# 20# s [>300 ns] 1,497.55 MeV
189Ta 188.96583(32)# 3# s [>300 ns] 7/2+# 1,505.63 MeV
190Ta 189.96923(43)# 0.3# s 1,513.70 MeV
I valori assegnati # non sono puramente derivati ​​da dati sperimentali, ma almeno parzialmente da tendenze sistematiche. Gira con argomenti di assegnazione deboli sono racchiusi tra parentesi. 14

Abbondanza

Terra - composti di origine: oxides 15
Terra - L'acqua di mare: 0.000002 mg/L 16
Terra -  Crosta:  2 mg/kg = 0.0002% 16
Terra -  Totale:  23.3 ppb 17
Pianeta Mercurio) -  Totale:  17.9 ppb 17
Venere -  Totale:  24.4 ppb 17
condriti - Totale: 0.016 (relative to 106 atoms of Si) 18

Composti

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Informazioni sulla sicurezza


Scheda di sicurezza - ACI Alloys, Inc.

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fonti

(1) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4:30.
(2) - Jolly, William L. The Chemistry of the Non-Metals; Prentice-Hall: Englewood Cliffs, New Jersey, 1966; p 119.
(3) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4:132.
(4) - Lide, David R. CRC Handbook of Chemistry and Physics, 84th ed.; CRC Press: Boca Raton, FL, 2002; p 4:39-4:96.
(5) - Dean, John A. Lange's Handbook of Chemistry, 11th ed.; McGraw-Hill Book Company: New York, NY, 1973; p 4:8-4:149.
(6) - Lide, David R. CRC Handbook of Chemistry and Physics, 84th ed.; CRC Press: Boca Raton, FL, 2002; p 10:147-10:148.
(7) - Speight, James. Lange's Handbook of Chemistry, 16th ed.; McGraw-Hill Professional: Boston, MA, 2004; p 1:132.
(8) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 10:178 - 10:180.
(9) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4:133.
(10) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:193, 12:219-220.
(11) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:123-6:137.
(12) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:107-6:122.
(13) - Dean, John A. Lange's Handbook of Chemistry, 12th ed.; McGraw-Hill Book Company: New York, NY, 1979; p 9:4-9:94.
(14) - Atomic Mass Data Center. http://amdc.in2p3.fr/web/nubase_en.html (accessed July 14, 2009).
(15) - Silberberg, Martin S. Chemistry: The Molecular Nature of Matter and Change, 4th ed.; McGraw-Hill Higher Education: Boston, MA, 2006, p 965.
(16) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 14:17.
(17) - Morgan, John W. and Anders, Edward, Proc. Natl. Acad. Sci. USA 77, 6973-6977 (1980)
(18) - Brownlow, Arthur. Geochemistry; Prentice-Hall, Inc.: Englewood Cliffs, NJ, 1979, pp 15-16.