MOLIBDÊNIO

Introdução

Número atômico: 42
Grupo: 6 or VI B
Peso atômico: 95.94
Período: 5
Número CAS: 7439-98-7

Classificação

Calcogênio
halogênio
Gás nobre
Lantanóides
Actinóide
Terra-rara
Platinum Metal Group
Transuranium
Não Isótopos Estáveis
Sólido
Líquido
Gás
Sólido (previsto)

Descrição • Usos / Função

Before Scheele recognized molybdenite as a distinct ore of a new element in 1778, it was confused with graphite and lead ore. The metal was preparedin an impure form in 1782 by Hjelm. Molybdenum does not occur native, but is obtained principally from molybdenite (MoS2). Wulfenite (PbMoO4)and Powellite (Ca(MoW)O4) are also minor commercial ores. Molybdenum is also recovered as a by-product of copper and tungsten mining operations.The metal is prepared from the powder made by the hydrogen reduction of purified molybdic trioxide or ammonium molybdate. The metal is silverywhite, very hard, but is softer and more ductile than tungsten. It has a high elastic modulus, and only tungsten and tantalum, of the more readily availablemetals, have higher melting points. It is a valuable alloying agent, as it contributes to the hardenability and toughness of quenched and tempered steels.It also improves the strength of steel at high temperatures. It is used in certain nickel-based alloys, such as the “Hastelloys (R)” which are heat-resistantand corrosion-resistant to chemical solutions. Molybdenum oxidizes at elevated temperatures. The metal has found recent application as electrodesfor electrically heated glass furnaces and forehearths. The metal is also used in nuclear energy applications and for missile and aircraft parts.Molybdenum is valuable as a catalyst in the refining of petroleum. It has found application as a filament material in electronic and electrical applications.Molybdenum is an essential trace element in plant nutrition. Some lands are barren for lack of this element in the soil. Molybdenum sulfide is usefulas a lubricant, especially at high temperatures where oils would decompose. Almost all ultra-high strength steels with minimum yield points up to300,000 psi (lb/sq. in.) contain molybdenum in amounts from 0.25 to 8%. Natural molybdenum contains seven isotopes. Twenty three other isotopes andisomers are known, all of which are radioactive. Molybdenum metal costs about $1/g (99.999% purity). Commercial molybdenum metal (99.9%) costsabout $200/kg. 1

• "enzymes, sulfur metabolism…essential for enzymes in humans and other animals" 2
• "Metallic molybdenum has important electrical uses as the supports of filaments in incandescent lamps and radio tubes, in resistance wires and contact points, on account of its high melting point." 3
• "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." 4
• "Mixed with molybdenum, scandium helps to inhibit the corrosion of zirconium." 5

Propriedades físicas

Ponto de fusão:6*  2623 °C = 2896.15 K = 4753.4 °F
Ponto de ebulição:6* 4639 °C = 4912.15 K = 8382.2 °F
Ponto de sublimação:6 
Ponto Triplo:6 
Ponto crítico:6 
Densidade:7  10.2 g/cm3

* - at 1 atm

Configuração Electron

Configuração Electron:  *[Kr] 5s1 4d5
Quadra: d
Mais alto nível de energia Ocupado: 5
Elétrons de valência: 

Números quânticos:

n = 4
ℓ = 2
m = 2
ms = +½

Colagem

Eletronegatividade (escala Pauling):8 2.16
Electropositivity (escala Pauling): 1.84
Electron Affinity:9 0.748 eV
oxidação Unidos: +6,3,5
Função no trabalho:10 4.30 eV = 6.8886E-19 J

potencial de ionização   eV 11  kJ/mol  
1 7.09243    684.3
2 16.16    1559.2
3 27.13    2617.6
4 46.4    4476.9
5 54.49    5257.5
6 68.8276    6640.9
7 125.664    12124.7
8 143.6    13855.3
9 164.12    15835.2
10 186.4    17984.9
potencial de ionização   eV 11  kJ/mol  
11 209.3    20194.4
12 230.28    22218.6
13 279.1    26929.0
14 302.6    29196.5
15 544    52488.0
16 570    54996.6
17 636    61364.7
18 702    67732.7
19 767    74004.2
20 833    80372.3
potencial de ionização   eV 11  kJ/mol  
21 902    87029.7
22 968    93397.8
23 1020    98415.0
24 1082    104397.1
25 1263    121860.9
26 1323    127650.1
27 1387    133825.1
28 1449    139807.2
29 1535    148104.9
30 1601    154473.0

Termoquímica

Calor específico: 0.251 J/g°C 12 = 24.081 J/mol°C = 0.060 cal/g°C = 5.755 cal/mol°C
Condutividade térmica: 138 (W/m)/K, 27°C 13
Calor de fusão: 32 kJ/mol 14 = 333.5 J/g
Calor da vaporização: 598 kJ/mol 15 = 6233.1 J/g
Estado da matéria Entalpia de formação (ΔHf°)16 entropia (S°)16 Gibbs Energia Livre (ΔGf°)16
(kcal/mol) (kJ/mol) (cal/K) (J/K) (kcal/mol) (kJ/mol)
(s) 0 0 6.85 28.6604 0 0
(g) 157.3 658.1432 43.461 181.840824 146.4 612.5376

isótopos

nuclide Massa 17 Meia vida 17 spin nuclear 17 Energia de ligação
100Mo 99.907477(6) 8.5(5)E+18 a 0+ 860.90 MeV
101Mo 100.910347(6) 14.61(3) min 1/2+ 866.18 MeV
102Mo 101.910297(22) 11.3(2) min 0+ 874.25 MeV
103Mo 102.91321(7) 67.5(15) s (3/2+) 882.32 MeV
104Mo 103.91376(6) 60(2) s 0+ 890.39 MeV
105Mo 104.91697(8) 35.6(16) s (5/2-) 898.46 MeV
106Mo 105.918137(19) 8.73(12) s 0+ 906.53 MeV
107Mo 106.92169(17) 3.5(5) s (7/2-) 905.29 MeV
108Mo 107.92345(21)# 1.09(2) s 0+ 913.36 MeV
109Mo 108.92781(32)# 0.53(6) s (7/2-)# 921.43 MeV
110Mo 109.92973(43)# 0.27(1) s 0+ 929.50 MeV
111Mo 110.93441(43)# 200# ms [>300 ns] 928.26 MeV
112Mo 111.93684(64)# 150# ms [>300 ns] 0+ 936.33 MeV
113Mo 112.94188(64)# 100# ms [>300 ns] 935.09 MeV
114Mo 113.94492(75)# 80# ms [>300 ns] 0+ 943.16 MeV
115Mo 114.95029(86)# 60# ms [>300 ns] 941.92 MeV
83Mo 82.94874(54)# 23(19) ms [6(+30-3) ms] 3/2-# 685.50 MeV
84Mo 83.94009(43)# 3.8(9) ms [3.7(+10-8) s] 0+ 701.02 MeV
85Mo 84.93655(30)# 3.2(2) s (1/2-)# 712.82 MeV
86Mo 85.93070(47) 19.6(11) s 0+ 726.48 MeV
87Mo 86.92733(24) 14.05(23) s 7/2+# 737.34 MeV
88Mo 87.921953(22) 8.0(2) min 0+ 751.00 MeV
89Mo 88.919480(17) 2.11(10) min (9/2+) 760.94 MeV
90Mo 89.913937(7) 5.56(9) h 0+ 774.60 MeV
91Mo 90.911750(12) 15.49(1) min 9/2+ 784.53 MeV
92Mo 91.906811(4) ESTÁVEL 0+ 797.26 MeV
93Mo 92.906813(4) 4.0(8)E+3 a 5/2+ 805.33 MeV
94Mo 93.9050883(21) ESTÁVEL 0+ 814.34 MeV
95Mo 94.9058421(21) ESTÁVEL 5/2+ 822.41 MeV
96Mo 95.9046795(21) ESTÁVEL 0+ 831.41 MeV
97Mo 96.9060215(21) ESTÁVEL 5/2+ 837.62 MeV
98Mo 97.9054082(21) ESTÁVEL 0+ 846.62 MeV
99Mo 98.9077119(21) 2.7489(6) d 1/2+ 852.83 MeV
Os valores marcados # não são puramente derivado a partir de dados experimentais, mas, pelo menos, parcialmente a partir de tendências sistemáticas. Gira com argumentos de atribuição fracos estão entre parênteses. 17

Abundância

Terra - Os compostos de origem: sulfides 18
Terra - A água do mar: 0.01 mg/L 19
Terra -  crosta:  1.2 mg/kg = 0.00012% 19
Terra -  Total:  2.35 ppm 20
Planeta Mercúrio) -  Total:  1.81 ppm 20
Vênus -  Total:  2.47 ppm 20
condritos - Total: 2.5 (relative to 106 atoms of Si) 21
Corpo humano - Total: 0.00001% 22

compostos

preços





Informação de Segurança


Material Safety Data Sheet - ACI Alloys, Inc.

Para maiores informações

Links externos:

revistas:
(1) Raloff, Janet. Desperately Seeking Moly. Science News, September 26, 2009, pp 16-20.

Fontes

(1) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4:19-4:20.
(2) - Whitten, Kenneth W., Davis, Raymond E., and Peck, M. Larry. General Chemistry 6th ed.; Saunders College Publishing: Orlando, FL, 2000; p 926-7.
(3) - Brownlee, Raymond B., Fuller, Robert W., and Whitsit, Jesse E. Elements of Chemistry; Allyn and Bacon: Boston, Massachusetts, 1959; p 560.
(4) - Jolly, William L. The Chemistry of the Non-Metals; Prentice-Hall: Englewood Cliffs, New Jersey, 1966; p 119.
(5) - Halka, Monica and Nordstrom, Brian. Transition Metals; Infobase Publishing: New York, NY, 2011; p 10.
(6) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4:132.
(7) - Lide, David R. CRC Handbook of Chemistry and Physics, 84th ed.; CRC Press: Boca Raton, FL, 2002; p 4:39-4:96.
(8) - Dean, John A. Lange's Handbook of Chemistry, 11th ed.; McGraw-Hill Book Company: New York, NY, 1973; p 4:8-4:149.
(9) - Lide, David R. CRC Handbook of Chemistry and Physics, 84th ed.; CRC Press: Boca Raton, FL, 2002; p 10:147-10:148.
(10) - Speight, James. Lange's Handbook of Chemistry, 16th ed.; McGraw-Hill Professional: Boston, MA, 2004; p 1:132.
(11) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 10:178 - 10:180.
(12) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4:133.
(13) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:193, 12:219-220.
(14) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:123-6:137.
(15) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; pp 6:107-6:122.
(16) - Dean, John A. Lange's Handbook of Chemistry, 12th ed.; McGraw-Hill Book Company: New York, NY, 1979; p 9:4-9:94.
(17) - Atomic Mass Data Center. http://amdc.in2p3.fr/web/nubase_en.html (accessed July 14, 2009).
(18) - Silberberg, Martin S. Chemistry: The Molecular Nature of Matter and Change, 4th ed.; McGraw-Hill Higher Education: Boston, MA, 2006, p 965.
(19) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 14:17.
(20) - Morgan, John W. and Anders, Edward, Proc. Natl. Acad. Sci. USA 77, 6973-6977 (1980)
(21) - Brownlow, Arthur. Geochemistry; Prentice-Hall, Inc.: Englewood Cliffs, NJ, 1979, pp 15-16.
(22) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 7:17.