Molybdenum

Molybdenum, ₄₂Mo

Molybdenum
Pronunciation	/məˈlɪbdənəm/ (listenⓘ) ​(mə-LIB-də-nəm)
Appearance	gray metallic
Standard atomic weight Ar°(Mo)
	95.95(1)[1]
Molybdenum in the periodic table
Hydrogen Helium Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine Xenon Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury (element) Thallium Lead Bismuth Polonium Astatine Radon Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson Cr ↑ Mo ↓ W niobium ← molybdenum → technetium
Atomic number (Z)	42
Group	group 6
Period	period 5
Block	d-block
Electron configuration	[Kr] 4d5 5s1
Electrons per shell	2, 8, 18, 13, 1
Physical properties
Phase at STP	solid
Melting point	2896 K ​(2623 °C, ​4753 °F)
Boiling point	4912 K ​(4639 °C, ​8382 °F)
Density (near r.t.)	10.28 g/cm3
when liquid (at m.p.)	9.33 g/cm3
Heat of fusion	37.48 kJ/mol
Heat of vaporization	598 kJ/mol
Molar heat capacity	24.06 J/(mol·K)
Vapor pressure P (Pa) 1 10 100 1 k 10 k 100 k at T (K) 2742 2994 3312 3707 4212 4879
Atomic properties
Oxidation states	−4, −2, −1, 0, +1,[2] +2, +3, +4, +5, +6 (a strongly acidic oxide)
Electronegativity	Pauling scale: 2.16
Ionization energies	1st: 684.3 kJ/mol 2nd: 1560 kJ/mol 3rd: 2618 kJ/mol
Atomic radius	empirical: 139 pm
Covalent radius	154±5 pm
Spectral lines of molybdenum
Other properties
Natural occurrence	primordial
Crystal structure	​body-centered cubic (bcc)
Speed of sound thin rod	5400 m/s (at r.t.)
Thermal expansion	4.8 µm/(m⋅K) (at 25 °C)
Thermal conductivity	138 W/(m⋅K)
Thermal diffusivity	54.3 mm2/s (at 300 K)[3]
Electrical resistivity	53.4 nΩ⋅m (at 20 °C)
Magnetic ordering	paramagnetic[4]
Molar magnetic susceptibility	+89.0×10−6 cm3/mol (298 K)[5]
Young's modulus	329 GPa
Shear modulus	126 GPa
Bulk modulus	230 GPa
Poisson ratio	0.31
Mohs hardness	5.5
Vickers hardness	1400–2740 MPa
Brinell hardness	1370–2500 MPa
CAS Number	7439-98-7
History
Discovery	Carl Wilhelm Scheele (1778)
First isolation	Peter Jacob Hjelm (1781)
Isotopes of molybdenum v e
Main isotopes[6] Decay abun­dance half-life (t1/2) mode pro­duct 92Mo 14.7% stable 93Mo synth 4×103 y ε 93Nb 94Mo 9.19% stable 95Mo 15.9% stable 96Mo 16.7% stable 97Mo 9.58% stable 98Mo 24.3% stable 99Mo synth 65.94 h β− 99mTc γ – 100Mo 9.74% 7.1×1018 y β−β− 100Ru
Category: Molybdenum view talk edit | references

Molybdenum is a chemical element. It has the chemical symbol Mo. It has the atomic number 42. It has 35 isotopes. The name Molybdenum is from the Greek meaning "leadlike". The color of pure molybdenum is silvery-white. It does not occur naturally, and is made from molybdenite.^[7]

It is used in alloys with other metals like stainless steel. It helps to make metal stronger, especially in high temperatures, and makes it less likely to rust.^[8] This makes it good for use in high speed tools, such as drills and saw blades.^[8] It is used in aircraft and missile parts, as well as in nuclear reactors.^[7] It is also not toxic, so it is used in making metal bowls for use in making food, medicines and other chemicals.^[8]

Molybdenum was used for many years before it was identified in 1778 by Swedish scientist, Carl Wilhelm Scheele. In 1782, Peter Jacob Hjelm was able to separate it into a dark powder he called "molybdenum".^[9] It was first mined in 1916 at Climax, near Leadville, in Colorado.