Introduction
Group: 6 or VI B
Atomic Weight: 95.94
Period: 5
CAS Number: 7439-98-7
Classification
No Stable Isotopes
Solid
Liquid
Gas
Solid (Predicted)
Description • Uses/Function
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
Physical Properties
Melting Point:6* 2623 °C = 2896.15 K = 4753.4 °F
Electron Configuration: *[Kr] 5s1 4d5
n = 4
Electronegativity (Pauling scale):8 2.16
Specific Heat: 0.251 J/g°C 12 = 24.081 J/mol°C = 0.060 cal/g°C = 5.755 cal/mol°C
Earth - Source Compounds: sulfides 18
External Links:
Magazines:
(1) - Lide, David R. CRC Handbook of Chemistry and Physics, 83rd ed.; CRC Press: Boca Raton, FL, 2002; p 4:19-4:20.
Boiling Point:6* 4639 °C = 4912.15 K = 8382.2 °F
Sublimation Point:6
Triple Point:6
Critical Point:6
Density:7 10.2 g/cm3
* - at 1 atm
Electron Configuration
Block: d
Highest Occupied Energy Level: 5
Valence Electrons:
Quantum Numbers:
ℓ = 2
mℓ = 2
ms = +½
Bonding
Electropositivity (Pauling scale): 1.84
Electron Affinity:9 0.748 eV
Oxidation States: +6,3,5
Work Function:10 4.30 eV = 6.8886E-19 J
Ionization Potential
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
Ionization Potential
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
Ionization Potential
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
Thermochemistry
Thermal Conductivity: 138 (W/m)/K, 27°C 13
Heat of Fusion: 32 kJ/mol 14 = 333.5 J/g
Heat of Vaporization: 598 kJ/mol 15 = 6233.1 J/g
State of Matter
Enthalpy of Formation (ΔHf°)16
Entropy (S°)16
Gibbs Free Energy (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
Isotopes
Nuclide
Mass 17
Half-Life 17
Nuclear Spin 17
Binding Energy
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)
STABLE
0+
797.26 MeV
93Mo
92.906813(4)
4.0(8)E+3 a
5/2+
805.33 MeV
94Mo
93.9050883(21)
STABLE
0+
814.34 MeV
95Mo
94.9058421(21)
STABLE
5/2+
822.41 MeV
96Mo
95.9046795(21)
STABLE
0+
831.41 MeV
97Mo
96.9060215(21)
STABLE
5/2+
837.62 MeV
98Mo
97.9054082(21)
STABLE
0+
846.62 MeV
99Mo
98.9077119(21)
2.7489(6) d
1/2+
852.83 MeV
Values marked # are not purely derived from experimental data, but at least partly from systematic trends. Spins with weak assignment arguments are enclosed in parentheses. 17
Abundance
Earth - Seawater: 0.01 mg/L 19
Earth -
Crust:
1.2 mg/kg = 0.00012% 19
Earth -
Total:
2.35 ppm 20
Mercury -
Total:
1.81 ppm 20
Venus -
Total:
2.47 ppm 20
Chondrites - Total: 2.5 (relative to 106 atoms of Si) 21
Human Body - Total: 0.00001% 22
Compounds
molybdenum(II) chloride; molybdenum dichloride
molybdenum(II) iodide
molybdenum(II) oxide
molybdenum(III) bromide
molybdenum(III) chloride
molybdenum(III) fluoride
molybdenum(III) iodide
molybdenum(III) nitride
Prices
Safety Information
Material Safety Data Sheet - ACI Alloys, Inc.
For More Information
American Elements
Chemical & Engineering News
Chemical Elements
ChemGlobe
Chemicool
Environmental Chemistry
(1) Raloff, Janet. Desperately Seeking Moly. Science News, September 26, 2009, pp 16-20.
Sources
(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.