Molybdenite ,the principal ore from which molybdenum is now extracted, was previously known as molybdena. Molybdena was confused with and often implemented as though it were graphite. Even when the two ores were distinguishable, molybdena was thought to be a lead ore. In 1754, Bengt Qvist examined the mineral and determined that it did not contain lead.

It was not until 1778 that Swedish chemist Carl Wilhelm Scheele realized molybdena was neither graphite nor lead. He and other chemists then correctly assumed that it was the ore of a distinct new element, named molybdenum for the mineral in which it was discovered.

Peter Jacob Hjelm successfully isolated molybdenum using carbon and linseed oil in 1781. For a long time there was no industrial use for molybdenum .

The French Schneider Electrics company produced the first steel molybdenum alloy armor plates in 1894. Until World War I most other armor factories also used molybdenum alloys. In World War I, some British tanks were protected by 75 mm (3.0 in) manganese plating, but this proved to be ineffective. The manganese plates were then replaced with 25 mm (0.98 in) molybdenum plating. These allowed for higher speed, greater maneuverability, and, despite being thinner, better protection.The high demand for molybdenum in World War I and World War II and the steep decrease after the wars had a great influence on prices and production of molybdenum .

Reported in EPA TSCA Inventory.

OSHA PEL: Soluble Compounds: TWA 5 mg(Mo)/m³; Insoluble Compounds: TWA Total Dust: 10 mg/m³; Respirable Fraction: 5 mg/m³
ACGIH TLV: Insoluble Compounds: TWA 10 mg(Mo)/m³; Soluble Compounds: TWA 0.5 mg(Mo)/m³ Confirmed Animal Carcinogen with Unknown Relevance to Humans
DFG MAK: (Insoluble Compounds) 4 mg/m³; (Soluble Compounds) 5 mg/m³

For occupational chemical analysis use NIOSH: Elements (ICP), 7300; Metals in Urine (ICP), 8310.

The Molybdenum, with the cas registry number 7439-98-7, is a kind of silvery white metal or grey powder. Being stable chemically, it is soluble in hot concentrated nitric acid, hot concentrated sulfuric acid, aqua regia, slightly soluble in hydrochloric acid while insoluble in cold and hot water, hydrofluoric acid and liquid ammonia. Besides, this chemical is incompatible with strong oxidizing agents such as bromine trifluoride, bromine pentafluoride, chlorine trifluoride, potassium perchlorate, nitryl fluoride, fluorine, iodine pentafluoride, sodium peroxide, lead dioxide.
 
Its product categories are various, including Intermediates of Dyes and Pigments; Inorganics; Metal and Ceramic Science; Metals; Molybdenum; AA Standard SolutionsAlphabetic; AAS; M; Matrix Selection; METI - MZSpectroscopy; OtherSpectroscopy; Reference/Calibration Standards; Single Solution; Standard Solutions; Catalysis and Inorganic Chemistry; Chemical Synthesis; MolybdenumMetal and Ceramic Science; 42: Mo; MolybdenumMaterials Science; Nanomaterials; Nanoparticles: Metals and Metal AlloysNanomaterials; Nanopowders and Nanoparticle Dispersions.

The physical properties of this chemical are as below: (1)#H bond acceptors: 0; (2)#H bond donors: 0; (3)#Freely Rotating Bonds: 0; (4)Polar Surface Area: 0; (5)Exact Mass: 97.905408; (6)MonoIsotopic Mass: 97.905408; (7)Heavy Atom Count: 1; (8)Covalently-Bonded Unit Count: 1.

The production method of this chemical: The industrial way of preparation is through the reduction of molybdenum trioxide by hydrogen. First heat the molybdenum trioxide to 600～700℃ and then restore this chemical at 1000～1100℃, then you could get this chemical, with the following equation: MoO₃+H₂→MoO₂+H₂O and MoO₂+2H₂→Mo+2H₂O.

As to its usage, it is widely applied in many fields. It could be used as large-scale slab as the material of molybdenum silicide heating element; It is also useful in the application that includes the manufacture of aircraft parts, electrical contacts, industrial motors, and filaments and also used in alloys for its high corrosion resistance and weldability. In addition, it is usually used as a solid lubricant and an extreme pressure (EP) antiwear agent and then as an adhesive between enamels and metals.

When you are dealing with this chemical, you should be much more careful. For one thing, it is irritant which may cause inflammation to the skin or other mucous membranes. And it is irritating to eyes and skin and may have risk of impaired fertility. For another thing, it is harmful which may cause damage to health. With the vapours which may cause drowsiness and dizziness, it may cause lung damage if swallowed. Besides, it may have danger of serious damage to health by prolonged exposure. In addition, it is highly flammable which may catch fire in contact with air, only needing brief contact with an ignition source, and it has a very low flash point or evolve highly flammable gases in contact with water. Beside all these, it is then dangerous for the environment which may present an immediate or delayed danger to one or more components of the environment. Being toxic to aquatic organisms, it may cause long-term adverse effects in the aquatic.
 
Due to so many dangers mentioned above, you should take different measures to deal with different cases. Wear suitable protective clothing, gloves and eye/face protection. And if in case of contact with eyes, rinse immediately with plenty of water and seek medical advice, and if swallowed, do not induce vomitting, seek medical advice immediately and show this container or label. When you are storing this chemical, keep container in a well-ventilated place, away from sources of ignition. What's more, avoid releasing to the environment and you could also refer to special instructions / safety data sheets.

In addition, you could convert the following datas into the molecular structure:
(1)Canonical SMILES: [Mo]
(2)InChI: InChI=1S/Mo
(3)InChIKey: ZOKXTWBITQBERF-UHFFFAOYSA-N 

Below are the toxicity information of this chemical: