Symbol	Mo
Atomic number	42
Group	6 (Chromium group)
Period	5
Block	d
Classification	Transition Metal

Appearance	Gray metallic
Color	Gray

Number of protons	42 p+
Number of neutrons	54 n0
Number of electrons	42 e-

From Wikipedia, the free encyclopediaMolybdenum is a chemical element with symbol Mo and atomic number 42. The name is from Neo-Latin molybdaenum, from Ancient Greek Μόλυβδος molybdos, meaning lead, since its ores were confused with lead ores. Molybdenum minerals have been known throughout history, but the element was discovered (in the sense of differentiating it as a new entity from the mineral salts of other metals) in 1778 by Carl Wilhelm Scheele.

Phase at STP	Solid
Density	10.28 g/cm3
Atomic weight	95.951 u

Melting point	2896 K 2622.85 °C 4753.13 °F
Boiling point	4912 K 4638.85 °C 8381.93 °F
Heat of vaporization	590.4 kJ/mol

Electronegativity (Pauling Scale)	2.16
Electron affinity	72.1 kJ/mol
Oxidation states	−4, −2, −1, 0, +1, +2, +3, +4, +5, +6 (a strongly acidic oxide)
Ionization energies	684.3 kJ/mol 1560 kJ/mol 2618 kJ/mol 4480 kJ/mol 5257 kJ/mol 6640.8 kJ/mol 12125 kJ/mol 13860 kJ/mol 15835 kJ/mol 17980 kJ/mol 20190 kJ/mol 22219 kJ/mol 26930 kJ/mol 29196 kJ/mol 52490 kJ/mol 55000 kJ/mol 61400 kJ/mol 67700 kJ/mol 74000 kJ/mol 80400 kJ/mol 87000 kJ/mol 93400 kJ/mol 98420 kJ/mol 104400 kJ/mol 121900 kJ/mol 127700 kJ/mol 133800 kJ/mol 139800 kJ/mol 148100 kJ/mol 154500 kJ/mol

Electron configuration Shorthand configuration	[Kr] 4d5 5s1
Electron configuration Full configuration	1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d5 5s1
Electron configuration chart	1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d5 5s1
Electrons per shell	2, 8, 18, 13, 1
Valence electrons	6
Valency electrons	2,3,4,5,6
Bohr model	Figure: Shell diagram of Molybdenum (Mo) atom.
Orbital Diagram	1s 2s 2p 3s 3p 3d 4s 4p 4d 5s

Discovery	Carl Wilhelm Scheele (1778)
First isolation	Peter Jacob Hjelm (1781)
Discovery of molybdenum Molybdenite—the principal ore from which molybdenum is now extracted—was previously known as molybdena. Molybdena was confused with and often utilized as though it were graphite. Like graphite, molybdenite can be used to blacken a surface or as a solid lubricant. Although (reportedly) molybdenum was deliberately alloyed with steel in one 14th-century Japanese sword (mfd. ca. 1330), that art was never employed widely and was later lost. In the West in 1754, Bengt Andersson Qvist examined a sample of molybdenite and determined that it did not contain lead and thus was not galena. By 1778 Swedish chemist Carl Wilhelm Scheele stated firmly that molybdena was (indeed) neither galena nor graphite. Instead, Scheele correctly proposed that molybdena was an ore of a distinct new element, named molybdenum for the mineral in which it resided, and from which it might be isolated. Peter Jacob Hjelm successfully isolated molybdenum using carbon and linseed oil in 1781.

CAS Number	7439-98-7
ChemSpider ID	22374
EC number	231-107-2
PubChem CID Number	23932