Molybdenum
Definition and meaning of Molybdenum in chemistry.
![Molybdenum element card: symbol Mo, atomic number 42, atomic mass 95.95, electron configuration [Kr] 4d⁵ 5s¹, oxidation states +6 +4, Transition metal, group 6, period 5, solid at room temperature.](/assets/images/terms/molybdenum-chemical-element.webp)
Molybdenum is a silvery-white and very hard transition metal with the chemical symbol Mo and an atomic number of 42. It possesses one of the highest melting points of all pure elements. This extreme heat resistance makes it critical for high-temperature metallurgy and advanced structural materials.
In more detail
Molybdenum is located in group 6 and period 5 of the periodic table. It does not occur naturally as a free metal anywhere on Earth. Instead, it exists in various oxidation states within minerals like molybdenite (MoS2) and wulfenite.
The element easily forms hard, remarkably stable carbides when mixed into liquid iron. Because of this, manufacturers use most molybdenum to create specialized, heavy-duty steel alloys. These unique metals include high-strength steel blends and superalloys used in aerospace engineering.
Molybdenum also serves a biologically essential role as a trace dietary element. It acts as a vital helper, or cofactor, for several important biological enzymes. These include critical life-sustaining enzymes like nitrogenase, nitrate reductase, and sulfite oxidase.
Chemically, the metal exhibits multiple oxidation states ranging from -2 to +6. It strongly resists attacks from harsh chemicals like hydrochloric acid and hydrofluoric acid. However, the pure metal will dissolve slowly when placed in hot, oxidizing acids.
At temperatures over 600 degrees Celsius, the solid metal oxidizes very rapidly. This rapid high-temperature oxidation forms a gas known as volatile molybdenum trioxide. Therefore, industrial high-temperature processing must happen in inert environments or strict vacuum conditions.
Key facts
| Field | General Chemistry |
|---|---|
| Symbol | Mo |
| Atomic number | 42 |
| Atomic mass | 95.95 u |
| Category | Transition-Metal |
| Melting point | 2623 °C |
| Boiling point | 4639 °C |
| Year discovered | 1778 |
Molybdenum disulfide (MoS2) is heavily used as a solid dry lubricant. Engineers apply it to machinery in high-temperature or high-vacuum mechanical environments. Typical petroleum-based greases would break down or instantly vaporize under these extreme conditions.
Frequently asked questions
Why is molybdenum added to steel?
It substantially increases the steel's strength, electrical conductivity, and resistance to corrosion and wear. These upgrades are vital for building structural steel, military armor plates, and aircraft parts.
How does molybdenum function in the human body?
Molybdenum acts as a critical cofactor for several crucial biological enzymes. These enzymes help the body break down amino acids and safely metabolize various drugs and toxins.
Related terms
Sources & references
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