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About Molybdenum

Molybdenum Bohr

The chemical and physical properties of molybdenum metal and its alloys are prized by a wide range of industries ranging from defense, avionics, metallurgy, glassmaking, pigments and dyes, organometallic chemistry, and the manufacturing of photovoltaics and semiconductor devices. A silvery gray transition metal, molybdenum is also one of therefractory metals, a group of metals with the shared properties of extremely high melting points and thermal conductivity, low thermal expansion and vapor pressure, excellent dimensional stability and creep resistance, and resistance to oxidation; its chemical behavior is similar to that of tungsten. Molybdenum has the sixth highest melting point of all elements and one of the lowest coefficients of thermal expansion among commercial metals, yet possesses a density only 25% higher than iron. It is the 54th most abundant element in the earth’s crust but does not occur freely in nature, rather present in oxide forms with various valence states. Common molybdenum-containing minerals include molybdenite (molybdenum sulfide), wulfenite (lead molybdate), and powellite; the metal is commercially produced via the direct mining of molybdenite as well as the production of tungsten and copper.

Molybdenum-containing minerals have been known since ancient times, but the element was often identified as lead; its current name is derived from the Ancient Greek word for lead, molybdos, owing to the confusion between lead sulfide and molybdenum sulfides, the latter of which was originally referred to as molybdena. Carl Wilhelm Scheele identified the element in 1778 by producing molybdenum oxide from molybdenite (naming it “terra molybdaenae”); in 1781, Peter Jacob Hjelm heated linseed oil and carbon combined with molybdic acid to yield the metal.

Molybdenum is toxic in high amounts but plays a critical biological role as a cofactor required for enyzme function; it did not play a significant commercial role until utilized in German artillery during World War II. Since then, its role as an alloying agent has composed more than 75% of its usage; often referred to as “moly,” it lends numerous advantages including increased hardness, strength, creep resistance, resistance to wear and corrosion, weldability, and stability in high stress, high temperature environments. Besides quenched and tempered steels, prevalent molybdenum alloys used in x-ray tubes, forging tools, and other applications include Hastelloys, ferromolybdenum, Titanium-Zirconium-Molybdenum (TZM), and Molybdenum-Lanthanum (lanthanated moly, or MoLa) which exhibits higher strength and dimensional stability than TZM. Commercial products that benefit from the use of molybdenum include armor, aircraft engine components, glass melting electrodes, valves, boiler plates, ribbons and wires for lighting, semiconductor base plates, hot-zones and heat sinks, sputtering targets for photovoltaic cell coatings and flat screens, crucibles for sapphire growth, circuit inks, and microwave devices. The isotope Molybdenum-99 is also used in nuclear imaging.

Molybdenum compounds are often used as industrial catalysts for removal of sulfide compounds from crude oil, converting water to hydrogen gas, producing formaldehyde and acrylonitrile, and, in the case of the n-type semiconductor molybdenum trioxide, acting as a photocatalyst; other applications include lubricants and pigments. Molybdenum disulfide and molybdensum diselenide have the ability to form two-dimensional thin films analgous to those of carbon (in the form of graphene) for use in flexible electronics; electrodes composed of MoS2-graphene nanosheet composites vastly improve performance of next-generation sodium air batteries.

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Molybdenum is used in high-pressure and high-temperature environments as pigments and catalysts. It is also found used in nuclear reactors, aerospace components, and some forms of steel alloys to add hardness and raise melting points. High Purity (99.999%) Molybdenum Oxide (MoO3) Powder Molybdenum is available as metal and compounds with purities from 99% to 99.999% (ACS grade to ultra-high purity). High Purity (99.999%) Molybdenum (Mo) Sputtering Target Elemental or metallic forms include pellets, rod, wire and granules for evaporation source material purposes. Molybdenum nanoparticles and nanopowders are also available. Molybedenum oxides are available in powder and dense pellet form for such uses as optical coating and thin film applications.Oxides tend to be insoluble. Molybdenum fluorides are other insoluble forms for uses in which oxygen is undesirable such as metallurgy, chemical and physical vapor deposition and in some optical coatings. Molybdenum is also available in soluble forms including chlorides, nitrates and acetates. These compounds can be manufactured as solutions at specified stoichiometries.

Molybdenum Properties

Molybdenum (Mo) atomic and molecular weight, atomic number and elemental symbolMolybdenum is a Block D, Group 6, Period 5 element. Molybdenum Bohr ModelThe number of electrons in each of molybdenum's shells is 2, 8, 18, 13, 1 and its electronic configuration is [Kr] 4d5 5s1. The molybdenum atom has a radius of and its Van der Waals radius is In its elemental form, CAS 7439-98-7, molybdenum has a gray metallic appearance. Elemental MolybdenumMolybdenum is the 54th most abundant element in the earth's crust. It has the third highest melting point of any element, exceeded only by tungsten and tantalum. Molybdenum does not occur naturally as a free metal, it is found in various oxidation states in minerals. The primary commercial source of molybdenum is molybdenite, although it is also recovered as a byproduct of copper and tungsten mining. Molybdenum was first discovered by Carl Wilhelm in 1778. The origin of the name molybdenum comes from the Greek word molubdos meaning lead.

Symbol: Mo
Atomic Number: 42
Atomic Weight: 95.96
Element Category: transition metal
Group, Period, Block: 6, 5, d
Color: gray metallic/ gray-white
Other Names: Molybdéne, Molibdeno
Melting Point: 2622°C, 4751.6°F, 2895.15 K
Boiling Point: 4639°C, 8382.2°F, 4912.15 K
Density: 10.28 g·cm3
Liquid Density @ Melting Point: 9.33 g·cm3
Density @ 20°C: 10.2 g/cm3
Density of Solid: 10280 kg·m3
Specific Heat: 0.25 (kJ/kg K)
Superconductivity Temperature: 0.915 [or -272.235 °C (-458.02 °F)] K
Triple Point: N/A
Critical Point: N/A
Heat of Fusion (kJ·mol-1): 27.6
Heat of Vaporization (kJ·mol-1): 589.9
Heat of Atomization (kJ·mol-1): 656.55
Thermal Conductivity: 138 W·m-1·K-1
Thermal Expansion: (25 °C) 4.8 µm·m-1·K-1
Electrical Resistivity: (20 °C) 53.4 nΩ·m
Tensile Strength: N/A
Molar Heat Capacity: 24.06 J·mol-1·K-1
Young's Modulus: 329 GPa
Shear Modulus: 126 GPa
Bulk Modulus: 230 GPa
Poisson Ratio: 0.31
Mohs Hardness: 5.5
Vickers Hardness: 1530 MPa
Brinell Hardness: 1500 MPa
Speed of Sound: (r.t.) 5400 m·s-1
Pauling Electronegativity: 2.16
Sanderson Electronegativity: 1.15
Allred Rochow Electronegativity: 1.3
Mulliken-Jaffe Electronegativity: N/A
Allen Electronegativity: N/A
Pauling Electropositivity: 1.84
Reflectivity (%): 58
Refractive Index: N/A
Electrons: 42
Protons: 42
Neutrons: 54
Electron Configuration: [Kr] 4d5 5s1
Atomic Radius: 139 pm
Atomic Radius,
non-bonded (Å):
Covalent Radius: 154±5 pm
Covalent Radius (Å): 1.46
Van der Waals Radius: 200 pm
Oxidation States: 6, 5, 4, 3, 2, 1, -1, -2 (strongly acidic oxide)
Phase: Solid
Crystal Structure: body-centered cubic
Magnetic Ordering: paramagnetic
Electron Affinity (kJ·mol-1) 72.146
1st Ionization Energy: 684.32 kJ·mol-1
2nd Ionization Energy: 1559.21 kJ·mol-1
3rd Ionization Energy: 2617.67 kJ·mol-1
CAS Number: 7439-98-7
EC Number: 231-107-2
MDL Number: MFCD00003465
Beilstein Number: N/A
SMILES Identifier: [Mo]
InChI Identifier: InChI=1S/Mo
PubChem CID: 23932
ChemSpider ID: 22374
Earth - Total: 2.35 ppm
Mercury - Total: 1.81 ppm
Venus - Total: 2.47 ppm
Earth - Seawater (Oceans), ppb by weight: 10
Earth - Seawater (Oceans), ppb by atoms: 0.64
Earth -  Crust (Crustal Rocks), ppb by weight: 1100
Earth -  Crust (Crustal Rocks), ppb by atoms: 230
Sun - Total, ppb by weight: 9
Sun - Total, ppb by atoms: 0.1
Stream, ppb by weight: 0.8
Stream, ppb by atoms: 0.008
Meterorite (Carbonaceous), ppb by weight: 1200
Meterorite (Carbonaceous), ppb by atoms: 250
Typical Human Body, ppb by weight: 100
Typical Human Body, ppb by atom: 7
Universe, ppb by weight: 5
Universe, ppb by atom: 0.1
Discovered By: Carl Wilhelm Scheele
Discovery Date: 1778
First Isolation: Peter Jacob Hjelm (1781)

Health, Safety & Transportation Information for Molybdenum

Molybdenum is toxic unless it is in small quantities. Safety data for Molybdenum and its compounds can vary widely depending on the form. For potential hazard information, toxicity, and road, sea and air transportation limitations, such as DOT Hazard Class, DOT Number, EU Number, NFPA Health rating and RTECS Class, please see the specific material or compound referenced in the Products tab. The below information applies to elemental (metallic) Molybdenum.

Safety Data
Material Safety Data Sheet MSDS
Signal Word Danger
Hazard Statements H228
Hazard Codes F
Risk Codes 11
Safety Precautions 9-16-36/37/39
RTECS Number QA4680000
Transport Information UN 3089 4.1/PG 2
WGK Germany nwg
Globally Harmonized System of
Classification and Labelling (GHS)

Molybdenum Isotopes

Molybdenum has 5 stable isotopes:

Nuclide Isotopic Mass Half-Life Mode of Decay Nuclear Spin Magnetic Moment Binding Energy (MeV) Natural Abundance
(% by atom)
83Mo 82.94874(54)# 23(19) ms [6(+30-3) ms] ß+ to 83Nb; ß+ + p to 82Zr 3/2-# N/A 671.85 -
84Mo 83.94009(43)# 3.8(9) ms [3.7(+10-8) s] ß+ to 84Nb 0+ N/A 687.38 -
85Mo 84.93655(30)# 3.2(2) s ß+ to 85Nb (1/2-)# N/A 699.19 -
86Mo 85.93070(47) 19.6(11) s ß+ to 86Nb 0+ N/A 712.86 -
87Mo 86.92733(24) 14.05(23) s ß+ to 87Nb; ß+ + p to 86Zr 7/2+# N/A 723.73 -
88Mo 87.921953(22) 8.0(2) min ß+ to 88Nb 0+ N/A 737.4 -
89Mo 88.919480(17) 2.11(10) min ß+ to 89Nb (9/2+) N/A 747.34 -
90Mo 89.913937(7) 5.56(9) h EC to 90Nb 0+ N/A 761.01 -
91Mo 90.911750(12) 15.49(1) min EC to 91Nb 9/2+ N/A 770.95 -
92Mo 91.906811(4) Observationally Stable - 0+ N/A 783.69 14.84
93Mo 92.906813(4) 4.0(8)E+3 y EC to 93Nb 5/2+ N/A 791.77 -
94Mo 93.9050883(21) STABLE - 0+ N/A 800.78 9.25
95Mo 94.9058421(21) STABLE - 5/2+ -0.9142 808.86 15.92
96Mo 95.9046795(21) STABLE - 0+ N/A 817.87 16.68
97Mo 96.9060215(21) STABLE - 5/2+ -0.9335 824.08 9.55
98Mo 97.9054082(21) Observationally Stable - 0+ N/A 833.09 24.13
99Mo 98.9077119(21) 2.7489(6) d ß- to 99Tc 1/2+ 0.375 839.31 -
100Mo 99.907477(6) 8.5(5)E+18 y - to 100Ru 0+ N/A 847.39 9.63
101Mo 100.910347(6) 14.61(3) min ß- to 101Tc 1/2+ N/A 852.67 -
102Mo 101.910297(22) 11.3(2) min ß- to 102Tc 0+ N/A 860.75 -
103Mo 102.91321(7) 67.5(15) s ß- to 103Tc (3/2+) N/A 868.83 -
104Mo 103.91376(6) 60(2) s ß- to 104Tc 0+ N/A 876.91 -
105Mo 104.91697(8) 35.6(16) s ß- to 105Tc (5/2-) N/A 884.98 -
106Mo 105.918137(19) 8.73(12) s ß- to 106Tc 0+ N/A 893.06 -
107Mo 106.92169(17) 3.5(5) s ß- to 107Tc (7/2-) N/A 891.83 -
108Mo 107.92345(21)# 1.09(2) s ß- to 108Tc 0+ N/A 899.9 -
109Mo 108.92781(32)# 0.53(6) s ß- to 109Tc (7/2-)# N/A 907.98 -
110Mo 109.92973(43)# 0.27(1) s ß- to 110Tc; ß- + n to 109Tc 0+ N/A 916.06 -
111Mo 110.93441(43)# 200# ms [>300 ns] ß- to 111Tc N/A N/A 914.82 -
112Mo 111.93684(64)# 150# ms [>300 ns] ß- to 112Tc 0+ N/A 922.9 -
113Mo 112.94188(64)# 100# ms [>300 ns] ß- to 113Tc N/A N/A 921.67 -
114Mo 113.94492(75)# 80# ms [>300 ns] Unknown 0+ N/A 929.74 -
115Mo 114.95029(86)# 60# ms [>300 ns] Unknown N/A N/A 928.51 -