introduzione
Gruppo: 5 or VI B
Peso atomico: 92.90638
Periodo: 5
Numero CAS: 7440-03-1
Classificazione
Non ci sono isotopi stabili
Solido
Liquido
Gas
Solido (previsto)
Descrizione • Usi / Funzione
Discovered in 1801 by Hatchett in an ore sent to England more that a century before by John Winthrop the Younger, first governor of Connecticut. The metal was first prepared in 1864 by Blomstrand, who reduced the chloride by heating it ina hydrogen atmosphere. The name niobium was adopted by the International Union of Pure and Applied Chemistry in 1950 after 100 years ofcontroversy. Many leading chemical societies and government organizations refer to it by this name. Most metallurgists, leading metal societies, andall but one of the leading U.S. commercial producers, however, still refer to the metal as “columbium”. The element is found in niobite(or columbite),niobite-tantalite, pyrochlore, and euxenite. Large deposits of niobium have been found associated with carbonatites (carbon-silicate rocks), as aconstituent of pyrochlore. Extensive ore reserves are found in Canada, Brazil, Nigeria, Zaire, and in Russia. The metal can be isolated from tantalum,and prepared in several ways. It is a shiny, white, soft, and ductile metal, and takes on a bluish cast when exposed to air at room temperatures for along time. The metal starts to oxidize in air at 200°C, and when processed at even moderate temperatures must be placed in a protective atmosphere.It is used in arc-welding rods for stabilized grades of stainless steel. Thousands of pounds of niobium have been used in advance air frame systemssuch as were used in the Gemini space program. The element has superconductive properties; superconductive magnets have been made with Nb-Zrwire, which retains its superconductivity in strong magnetic fields. This type of application offers hope of direct large-scale generation of electricpower. Natural niobium is composed of only one isotope, 93Nb. Forty one other isotopes and isomers of niobium are now recognized. Niobium metal(99.9% pure) is priced at about $400/kg. 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* 2477 °C = 2750.15 K = 4490.6 °F
configurazione elettronica: *[Kr] 5s1 4d4
n = 4
elettronegatività (scala Pauling):5 1.6
Calore specifico: 0.265 J/g°C 9 = 24.620 J/mol°C = 0.063 cal/g°C = 5.884 cal/mol°C
Terra - composti di origine: oxides 15
Link esterno:
(1) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4:20-4:21.
Punto di ebollizione:3* 4744 °C = 5017.15 K = 8571.2 °F
sublimazione Point:3
Triple Point:3
Punto critico:3
Densità:4 8.57 g/cm3
* - at 1 atm
configurazione elettronica
Bloccare: d
Più alto livello di energia Occupato: 5
Elettroni di valenza:
numeri quantici:
ℓ = 2
mℓ = 1
ms = +½
bonding
Electropositivity (scala Pauling): 2.4
Affinità elettronica:6 0.893 eV
ossidazione Uniti: +5,3
Funzione di lavoro:7 4.20 eV = 6.7284E-19 J
potenziale di ionizzazione
eV 8
kJ/mol
1
6.75885
652.1
2
14.32
1381.7
potenziale di ionizzazione
eV 8
kJ/mol
3
25.04
2416.0
4
38.3
3695.4
potenziale di ionizzazione
eV 8
kJ/mol
5
50.55
4877.3
6
102.057
9847.0
7
125
12060.7
Termochimica
Conduttività termica: 53.7 (W/m)/K, 27°C 10
Calore di fusione: 26.4 kJ/mol 11 = 284.2 J/g
Calore di vaporizzazione: 682 kJ/mol 12 = 7340.7 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
8.70
36.4008
0
0
(g)
173.5
725.924
44.490
186.14616
162.8
681.1552
isotopi
nuclide
Massa 14
Metà vita 14
spin nucleare 14
Energia di legame
100Nb
99.914182(28)
1.5(2) s
1+
855.16 MeV
101Nb
100.915252(20)
7.1(3) s
(5/2#)+
866.96 MeV
102Nb
101.91804(4)
1.3(2) s
1+
875.03 MeV
103Nb
102.91914(7)
1.5(2) s
(5/2+)
883.10 MeV
104Nb
103.92246(11)
4.9(3) s
(1+)
881.86 MeV
105Nb
104.92394(11)
2.95(6) s
(5/2+)#
889.93 MeV
106Nb
105.92797(21)#
920(40) ms
2+#
898.00 MeV
107Nb
106.93031(43)#
300(9) ms
5/2+#
896.76 MeV
108Nb
107.93484(32)#
0.193(17) s
(2+)
904.83 MeV
109Nb
108.93763(54)#
190(30) ms
5/2+#
912.90 MeV
110Nb
109.94244(54)#
170(20) ms
2+#
911.66 MeV
111Nb
110.94565(54)#
80# ms [>300 ns]
5/2+#
919.73 MeV
112Nb
111.95083(75)#
60# ms [>300 ns]
2+#
918.48 MeV
113Nb
112.95470(86)#
30# ms [>300 ns]
5/2+#
926.56 MeV
81Nb
80.94903(161)#
<44 ns
3/2-#
669.21 MeV
82Nb
81.94313(32)#
51(5) ms
0+
682.87 MeV
83Nb
82.93671(34)
4.1(3) s
(5/2+)
697.46 MeV
84Nb
83.93357(32)#
9.8(9) s
3+
708.32 MeV
85Nb
84.92791(24)
20.9(7) s
(9/2+)
721.98 MeV
86Nb
85.92504(9)
88(1) s
(6+)
731.92 MeV
87Nb
86.92036(7)
3.75(9) min
(1/2-)
744.65 MeV
88Nb
87.91833(11)
14.55(6) min
(8+)
754.58 MeV
89Nb
88.913418(29)
2.03(7) h
(9/2+)
767.31 MeV
90Nb
89.911265(5)
14.60(5) h
8+
777.24 MeV
91Nb
90.906996(4)
680(130) a
9/2+
789.97 MeV
92Nb
91.907194(3)
3.47(24)E+7 a
(7)+
797.11 MeV
93Nb
92.9063781(26)
STABILE
9/2+
806.12 MeV
94Nb
93.9072839(26)
2.03(16)E+4 a
(6)+
813.26 MeV
95Nb
94.9068358(21)
34.991(6) d
9/2+
822.26 MeV
96Nb
95.908101(4)
23.35(5) h
6+
828.47 MeV
97Nb
96.9080986(27)
72.1(7) min
9/2+
836.54 MeV
98Nb
97.910328(6)
2.86(6) s
1+
842.75 MeV
99Nb
98.911618(14)
15.0(2) s
9/2+
849.89 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 - L'acqua di mare: 0.00001 mg/L 16
Terra -
Crosta:
20 mg/kg = 0.002% 16
Terra -
Totale:
800 ppb 17
Pianeta Mercurio) -
Totale:
610 ppb 17
Venere -
Totale:
840 ppb 17
condriti - Totale: 1.0 (relative to 106 atoms of Si) 18
Composti
niobium(III) bromide
niobium(III) chloride
niobium(III) fluoride
niobium(III) iodide
niobium(III) nitride
niobium(IV) bromide
Informazioni sulla sicurezza
Scheda di sicurezza - ACI Alloys, Inc.
Per maggiori informazioni
American Elements
Chemical & Engineering News
Chemical Elements
ChemGlobe
Chemicool
Environmental Chemistry
fonti
(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.