Content Curator
Minerals are defined as chemical elements that are required by our body to function efficiently. One among them is Molybdenum. Molybdenum (Mo) is a chemical element in the periodic table with the atomic number 42. In 1778, Carl Wilhelm Scheele discovered Molybdenum. Foods like cereal grains, milk, cheese, legumes, green vegetables, nuts, and organ meats all possess this mineral.
| Table of Content |
Key terms: Molybdenum, oxidation states, isotopes, atomic data, natural occurrence
Read More: Number of Moles Formula
What is Molybdenum?
[Click Here for Sample Questions]
As previously said, it is a chemical element and a vital mineral with a wide range of applications and functions. It is a silvery-white transition metal with one of the highest melting points of all pure elements.
Acids can gradually cause them harm. There are 35 distinct isotopes of molybdenum, with atomic masses ranging from 83 to 117. It also has a number of other names such as Ammonium Molybdate, Chélate de Molybdate, Chelated Molybdenum, Citrate de Molybdène, Etrathiomolybdate, Ionic Molybdenum, Mo, Molibdeno, Molybdate d'Ammonium, Molybdate de Sodium, Molybdene, Molybdène, Molybdenum Citrate, Molybdenum Picolinate, Sodium Molybdate.
Read More: Cisplatin
Properties of Molybdenum
[Click Here for Sample Questions]
| Particulars | Details |
|---|---|
| Symbol | Mo |
| Atomic Number | 42 |
| Atomic Mass | 95.95 |
| Discovered by | Molybdenum was discovered by Peter Jacob Hjelm |
Physical Properties
| Parameters | Details |
|---|---|
| Phase at STP | solid |
| 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) |
Chemical Properties
| Group | 6 | Melting point | 2622°C, 4752°F, 2895 K |
| Period | 5 | Boiling point | 4639°C, 8382°F, 4912 K |
| Block | d | Density (g cm−3) | 10.2 |
| Atomic number | 42 | Relative atomic mass | 95.95 |
| State at 20°C | Solid | Key isotopes | 95Mo, 96Mo, 98Mo |
| Electron configuration | [Kr] 4d5 5s1 | CAS number | 7439-98-7 |
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 |
| 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 |
Read More: Critical temperature
Uses of Molybdenum
[Click Here for Sample Questions]
- It is one of the greatest alloying agents owing to the fact that it has better strength at a higher temperature. It improves the strength of steel at high temperatures. And it is used in steel alloys to increase strength, hardness, electrical conductivity, and resistance to corrosion and wear. Furthermore, it is also applied for use in engines.
- It is even used as a fertilizer for some plants like cauliflower which is said to have Molybdenum deficiency. Although deficiency of Molybdenum is uncommon, experts recommend including cauliflower in one's diet to keep the mineral at a healthy level. Cauliflower is a source of Molybdenum due to the abundance of the mineral, Molybdenum in the fertilizers used for such plants.
- It is also used as a catalyst in the petroleum industry.
- Molybdenum disulfide is used as a lubricant additive.
- Other uses for molybdenum are namely- catalysts for the petroleum industry, inks for circuit boards, pigments, and electrodes.
Read More: Relation between Molarity and Molality
Things to Remember
- Symbol of Molybdenum – Mo
- Atomic Number – 42
- Atomic Mass – 95.95
- It is a silvery-white transition metal with one of the highest melting points of all pure elements.
- Molybdenite is the most common molybdenum ore (molybdenum disulfide). Roasting turns it into molybdenum oxide, which is then reduced to metal. The United States, China, Chile, and Peru are the primary mining regions. The manufacturing of tungsten and copper yields some molybdenum as a by-product. The annual global production is estimated to be over 200,000 tonnes.
Also Read:
Sample Questions
Ques. Explain the Electronic Configuration of Molybdenum. (3 Marks)
Ans: One may easily find any element's electron configuration if we know the basic guidelines for the electron configuration of the element when examining the atomic table. The electron configuration of Molybdenum is identical to that of gold. When we search up Molybdenum in the periodic table, we can note that it has an atomic number of 42.
According to the laws, there are two electrons in the initial orbit.
8 electrons in the second orbit
There are 18 electrons in the third orbit.
13 electrons in the fourth orbit and
1 electron in the fifth orbit.
Ques. Name and explain some compounds of Molybdenum. (3 Marks)
Ans: In oxidation levels ranging from -II to +VI, molybdenum yields chemical compounds. Higher oxidation states are more significant to its terrestrial occurrence and biological functions, while mid-level oxidation states are frequently connected with metal clusters and very low oxidation states are typically associated with organomolybdenum compounds.
The chemistry of Mo and W is strikingly similar. The rarity of molybdenum(III) compounds, for example, contrasts with the widespread presence of chromium(III) compounds. Molybdenum(VI) oxide (MoO3) has the highest oxidation state, whereas molybdenum disulfide (MoS2) is the usual sulphur compound.
The broad range of oxidation states of molybdenum is reflected in various molybdenum chlorides:
Molybdenum(II) chloride MoCl2, which exists as the hexamer Mo6Cl12 and the related dianion [Mo6Cl14]2-.
Molybdenum(III) chloride MoCl3, a dark red solid, which converts to the anion trianionic complex [MoCl6]3-.
Molybdenum(IV) chloride MoCl4, a black solid, which adopts a polymeric structure.
Molybdenum(V) chloride MoCl5 dark green solid, which adopts a dimeric structure.
Molybdenum(VI) chloride MoCl6 is a black solid, which is monomeric and slowly decomposes to MoCl5 and Cl2 at room temperature.
Ques. Give examples of various compounds of Molybdenum possessing the oxidation states ranging from -1 to +6. (3 Marks)
Ans:
| Oxidation state | Example |
|---|---|
| −1 | Na2[Mo2(CO)10] |
| 0 | MO(CO)6 |
| 1 | Na[C6H6Mo] |
| 2 | MoCl2 |
| 3 | MoBr3 |
| 4 | MoS2 |
| 5 | MoCl5 |
| 6 | MoF6 |
Ques. Give an account of the isotopes of Molybdenum. (3 Marks)
Ans:
| Isotope | Abundance | Half-life (t1/2) | Decay mode | Product |
|---|---|---|---|---|
| 92Mo | 14.65% | stable | - | - |
| 93Mo | syn | 4×103 y | ε | 93Nb |
| 94Mo | 9.19% | stable | - | - |
| 95Mo | 15.87% | stable | - | - |
| 96Mo | 16.67% | stable | - | - |
| 97Mo | 9.58% | stable | - | - |
| 98Mo | 24.29% | stable | - | - |
| 99Mo | syn | 65.94 h | β− | 99mTc |
| γ | – | - | - | - |
| 100Mo | 9.74% | 7.8×1018 y | β−β− | 100Ru |
Ques. Write a short note on the chemical element, Molybdenum. (3 Marks)
Ans. Molybdenum is the 42nd most plentiful element in the Universe, and it is the 54th most abundant element in the Earth's crust with an average of 1.5 parts per million and the 25th most abundant element in its oceans with an average of 10 parts per billion.
A molybdenum-bearing grain (1 0.6 m) was discovered in a pyroxene fragment retrieved from Mare Crisium on the Moon by the Russian Luna 24 mission. The relative scarcity of molybdenum in the Earth's crust is compensated for by its presence in a number of water-insoluble ores, which are frequently mixed with sulphur in the same way that copper is. Though molybdenum can be found in minerals like wulfenite (PbMoO4) and powellite (CaMoO4), molybdenite is the most common commercial source (MoS2).
Ques. Explain the role of Molybdenum in Human metabolism and deficiency. (3 Marks)
Ans. Molybdenum is a trace element that is required in the diet. Sulfite oxidase, xanthine oxidoreductase, aldehyde oxidase, and mitochondrial amidoxime reductase are four Mo-dependent enzymes that all include a pterin-based molybdenum cofactor (Moco) in their active site.
People who are severely low in molybdenum have a dysfunctional sulfite oxidase enzyme and are more susceptible to harmful reactions to sulfites in the diet. Molybdenum is found in the human body in amounts of 0.07 mg per kilogram body weight, with larger concentrations in the liver and kidneys and lower concentrations in the vertebrae. Human tooth enamel contains molybdenum, which may aid to prevent decay.
Ques. Mention the compounds of Molybdenum with their uses. (5 Marks)
Ans: Molybdenum disulfide (MoS2) is a solid lubricant and anti-wear compound used in high-pressure, high-temperature (HPHT) applications. It is a frequent ingredient to HPHT greases and creates robust films on metallic surfaces; in the case of a catastrophic grease failure, a thin layer of molybdenum prevents contact of the lubricated parts.
It also possesses semiconducting characteristics that give it an edge over regular silicon or graphene in electronics. MoS2 is also utilised as a catalyst in the hydrocracking of nitrogen, sulphur, and oxygen-containing petroleum fractions.
Molybdenum disilicide (MoSi2) is an electrically conductive ceramic used primarily in heating components that operate at temperatures greater than 1500 °C in air.
Molybdenum trioxide (MoO3) is employed as an adhesive between enamels and metals.
Wulfenite (lead molybdate) is a bright-orange pigment that is co-precipitated with lead chromate and lead sulphate and utilised in ceramics and plastics.
In the chemical industry, molybdenum-based mixed oxides are useful catalysts. Catalysts for carbon monoxide oxidation, selective oxidation of propylene to acrolein and acrylic acid, ammoxidation of glycerol, and propylene to acrylonitrile are some examples. Researchers are looking at catalysts and processes for the direct selective oxidation of propane to acrylic acid.
Molybdenum carbides, nitride, and phosphides can be used for the hydrotreatment of rapeseed oil.
Ammonium heptamolybdate is used in biological staining.
Molybdenum coated soda lime glass is used in CIGS (copper indium gallium selenide) solar cells, called CIGS solar cells.
Phosphomolybdic acid is a stain used in thin-layer chromatography.
Ques. How is Molybdenum related to Nitrogen fixation? (2 Marks)
Ans: The mineral molybdenum is required for nitrogen fixation by the nitrogenase enzyme. The nitrogenase provides electrons to nitrogen in stages during the reduction process which implies that electrons are carried over to nitrogen in order. The capacity of molybdenum to exist in a variety of oxidation states is ideal for this. Nitrogenase is therefore a molybdo flavoprotein.
Ques. Give a brief account of production of Molybdenum. (3 Marks)
Ans: In molybdenite processing, the ore is first roasted in air at a temperature of 700 °C (1,292 °F). The process gives gaseous sulfur dioxide and the molybdenum(VI) oxide:
2 MoS2 + 7 O2 → 2 MoO3 + 4 SO2
The oxidized ore is then usually extracted with aqueous ammonia to give ammonium molybdate:
MoO3 + 2 NH3 + H2 O → (NH4)2 (MoO4)
Copper, an impurity in molybdenite, is less soluble in ammonia. To completely remove it from the solution, it is precipitated with hydrogen sulphide. Ammonium molybdate converts to ammonium dimolybdate, which is isolated as a solid. Heating this solid gives molybdenum trioxide:
(NH4)2Mo2O7 → 2 MoO3 + 2 NH3 + H2O
Crude trioxide can be further purified by sublimation at 1,100 °C (2,010 °F).
Metallic molybdenum is produced by reduction of the oxide with hydrogen:
MoO3 + 3 H2 → Mo + 3 H2O
Ques. Write a short note on isotopes of Molybdenum. (3 Marks)
Ans: Molybdenum has 35 known isotopes with atomic masses ranging from 83 to 117, as well as four metastable nuclear isomers. There are seven naturally occurring isotopes with atomic masses of 92, 94, 95, 96, 97, 98, and 100. Only molybdenum-100 is unstable among these naturally occurring isotopes.
The isotope molybdenum-98 is the most common, accounting for 24.14 percent of all molybdenum. Molybdenum-100 has a half-life of around 1019 years and decays into ruthenium-100 by double beta decay. All unstable molybdenum isotopes decay into niobium, technetium, and ruthenium isotopes. The most stable synthetic radioisotope is 93Mo, which has a half-life of 4,000 years.
Molybdenum-99, a product of fission, is the most common isotopic molybdenum application. It is the parent radioisotope of the short-lived gamma-emitting daughter radioisotope technetium-99m, a nuclear isomer utilized in medical imaging. The Delft University of Technology filed a patent application in 2008 for molybdenum-98-based molybdenum-99 manufacture.
Do Check Out:
Comments