Molybdenum

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Molybdenum,  42Mo
Molybdenum crystaline fragment and 1cm3 cube.jpg
General properties
Appearance gray metallic
Staundart atomic wecht (Ar, staundart) 95.95(1)
Molybdenum in the periodic cairt
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 Airn Cobalt Nickel Capper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton
Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Siller (element) 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 Mercur (element) Thallium Leid (element) 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 Ununtrium Flerovium Ununpentium Livermorium Ununseptium Ununoctium
Cr

Mo

W
niobiummolybdenumtechnetium
Atomic nummer (Z) 42
Group group 6
Period period 5
Element category   transition metal
Block d-block
Electron confeeguration [Kr] 5s1 4d5
Electrons per shell
2, 8, 18, 13, 1
Pheesical properties
Phase (at STP) solit
Meltin pynt 2896 K ​(2623 °C, ​4753 °F)
Bylin pynt 4912 K ​(4639 °C, ​8382 °F)
Density (near r.t.) 10.28 g/cm3
when liquid (at m.p.) 9.33 g/cm3
Heat o fusion 37.48 kJ/mol
Heat o vapourisation 598 kJ/mol
Molar heat capacity 24.06 J/(mol·K)
Vapour pressur
P (Pa) 1 10 100 1 k 10 k 100 k
at T (K) 2742 2994 3312 3707 4212 4879
Atomic properties
Oxidation states 6, 5, 4, 3, 2, 1[1], -1, -2
(strongly acidic oxide)
Electronegativity Pauling scale: 2.16
Atomic radius empirical: 139 pm
Covalent radius 154±5 pm
Color lines in a spectral range
Miscellanea
Creestal structurbody-centred cubic (bcc)
Body-centered cubic creestal structur for molybdenum
Speed o soond 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[2] mm2/s (at 300 K)
Electrical resistivity 53.4 n Ω·m (at 20 °C)
Magnetic orderin paramagnetic[3]
Young's modulus 329 GPa
Shear modulus 126 GPa
Bouk modulus 230 GPa
Poisson ratio 0.31
Mohs haurdness 5.5
Vickers haurdness 1530 MPa
Brinell haurdness 1500 MPa
CAS Nummer 7439-98-7
History
Diskivery Carl Wilhelm Scheele (1778)
First isolation Peter Jacob Hjelm (1781)
Main isotopes o molybdenum
Iso­tope Abun­dance Hauf-life (t1/2) Decay mode Pro­duct
92Mo 14.84% >1.9×1020 y (β+β+) 92Zr
93Mo syn 4×103 y ε 93Nb
94Mo 9.25% - (SF)
95Mo 15.92% - (SF)
96Mo 16.68% - (SF)
97Mo 9.55% - (SF)
98Mo 24.13% >1×1014 y ββ 98Ru
99Mo syn 65.94 h β 99mTc
γ -
100Mo 9.63% 7.8×1018 y (ββ) 100Ru
Decay modes in parentheses is predict, but hisna yet been observed
| references | in Wikidata

Molybdenum is a Group 6 chemical element wi the seembol Mo an atomic nummer 42. The name is frae Neo-Laitin Molybdaenum, frae Auncient Greek Μόλυβδος molybdos, meanin leid, syne its ores wur confused wi leid ores.[4] Molybdenum meenerals hae been kent intae prehistory, but the element wis discovered (in the sense o differentiatin it as a new entity frae the mineral sauts o ither metals) in 1778 bi Carl Wilhelm Scheele. The metal wis first isolatit in 1781 bi Peter Jacob Hjelm.

Molybdenum disnae occur naiturally as a free metal on Yird, but rather in various oxidation states in meenerals. The free element, whilk is a sillery metal wi a gray cast, haes the saxt-heichest meltin pynt o ony element. It readily furms haird, stable carbides in alloys, an for this raison maist o warld production o the element (aboot 80%) is in makin mony types o steel alloys, includin heich strength alloys an superalloys.

Maist molybdenum compounds hae law solubility in watter, but the molybdate ion MoO2−
4
is soluble an furms whan molybdenum-containin meenerals are in contact wi oxygen an watter. Industrially, molybdenum compoonds (aboot 14% o warld production o the element) are uised in high-pressure an heich-temperatur applications, as pigments an catalysts.

Molybdenum-containin enzymes is bi far the maist common catalysts uised bi some bacteria tae break the chemical bond in atmospheric molecular nitrogen, allaein biological nitrogen fixation. At least 50 molybdenum-containin enzymes are nou kent in bacteria an ainimals, tho anly bacterial an cyanobacterial enzymes is involved in nitrogen fixation, an thirnitrogenases contain molybdenum in a different furm frae the rest. Awin tae the diverse functions o the various ither types o molybdenum enzymes, molybdenum is a required element for life in aw heicher organisms (eukaryotes), tho nae in aw bacteria.

References[eedit | eedit soorce]

  1. "Molybdenum: molybdenum(I) fluoride compound data". OpenMOPAC.net. Retrieved 2007-12-10. 
  2. A. Lindemann, J. Blumm (2009). Measurement of the Thermophysical Properties of Pure Molybdenum. 17th Plansee Seminar. 3. 
  3. Magnetic susceptibility of the elements and inorganic compounds, in Handbook of Chemistry and Physics 81st edition, CRC press.
  4. Lide, David R., ed. (1994). "Molybdenum". CRC Handbook of Chemistry and Physics. 4. Chemical Rubber Publishing Company. p. 18. ISBN 0-8493-0474-1.