{"id":89,"date":"2020-04-08T15:02:54","date_gmt":"2020-04-08T15:02:54","guid":{"rendered":"https:\/\/thechemicalelements.com\/?page_id=89"},"modified":"2023-08-16T09:48:22","modified_gmt":"2023-08-16T09:48:22","slug":"molybdenum","status":"publish","type":"post","link":"https:\/\/thechemicalelements.com\/molybdenum\/","title":{"rendered":"Molybdenum (Mo)"},"content":{"rendered":"\n

Molybdenum is a chemical element with the atomic number 42 in the periodic table. It occurs in an abundance of 1.5 parts per million in Earth\u2019s crust. This refractory metal has three valence electrons and adopts the oxidation states of +2 to +6 in the compounds. Out of all naturally occurring elements, only carbon<\/a>, tungsten<\/a>, rhenium<\/a>, osmium<\/a>, and tantalum<\/a> have higher melting points than molybdenum.<\/span><\/p>\n\n\n\n

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Chemical and Physical Properties of Molybdenum<\/span><\/h3>\n\n\n\n
Property<\/strong><\/td>Value<\/strong><\/td><\/tr>
Symbol<\/td>Mo<\/td><\/tr>
Name<\/td>Molybdenum<\/td><\/tr>
Atomic Number<\/td>42<\/td><\/tr>
Atomic Weight<\/td>95.94 g.mol-1<\/td><\/tr>
Group<\/td>6 (Refractory metal)<\/td><\/tr>
Period<\/td>5<\/td><\/tr>
Color<\/td>A silver-gray metal<\/td><\/tr>
Physical State<\/td>Solid at room temperature<\/td><\/tr>
Half-life<\/td>From 23(19) milliseconds to 1\u00d710\u00b9\u2079 years<\/td><\/tr>
Electronegativity<\/td>1.8<\/td><\/tr>
Density<\/td>10.2 g.cm-3 at 20\u00b0C<\/td><\/tr>
Melting Point<\/td>2622\u00b0C, 4752\u00b0F, 2895 K<\/td><\/tr>
Boiling Point<\/td>4639\u00b0C, 8382\u00b0F, 4912 K<\/td><\/tr>
Van der Waals Radius<\/td>0.139 nm<\/td><\/tr>
Ionic Radius<\/td>0.068 nm (+4) ; 0.06 nm (+6)<\/td><\/tr>
Isotopes<\/td>33<\/td><\/tr>
Most Characteristic Isotope<\/td>95Mo, 96Mo, 98Mo<\/td><\/tr>
Electronic Shell<\/td>[Kr] 4d\u2075 5s\u00b9<\/td><\/tr>
The Energy of the First Ionization<\/td>651 kJ.mol-1<\/td><\/tr>
The Energy of the Second Ionization<\/td>N\/A<\/td><\/tr>
Discovery Date<\/td>1781<\/td><\/tr>
Discovered By<\/td>Peter Jacob Hjelm<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
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With the periodic table symbol Mo, atomic number 42, atomic mass of 95.94 g.mol<\/span>-1<\/span>, and electron configuration [Kr] 4d5<\/span>5<\/span>s<\/span>1<\/span>, molybdenum is a silver-gray refractory and corrosion-resistant metal. It\u2019s very hard and tough, but also softer and more ductile than tungsten.<\/span><\/p>\n\n\n\n

Molybdenum reaches its boiling point at 4639\u00b0C, 8382\u00b0F, 4912 K, while the melting point is achieved at X2622\u00b0C, 4752\u00b0F, 2895 K. This refractory metal has an electronegativity of 1.8 according to Pauling, whereas the atomic radius according to van der Waals is 0.139 nm. It\u2019s non-reactive with oxygen or water at room temperature.\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0<\/span><\/p>\n\n\n\n

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How Was Molybdenum Discovered?<\/span><\/h2>\n\n\n\n

Until 1778, the soft black mineral molybdenite (molybdenum sulfide, MoS<\/span>2<\/span>) was assumed to be a lead ore. The same year, the Swedish chemist Carl W. Scheele (1742 – 1786) attempted an experiment on a molybdenite sample in order to prove his belief that there\u2019s a new, undiscovered element in the substance. Indeed, he succeeded in proving that the mineral molybdaina (now molybdenite) contains sulfur<\/a> and a new, unknown metal. Unfortunately, he wasn\u2019t able to isolate it. <\/span><\/p>\n\n\n\n

After a series of unsuccessful trials, Sheele decided to ask his fellow colleague, the Swedish chemist Peter Jacob Hjelm for assistance. Following Sheele\u2019s advice and directions, Hjelm finally managed to isolate the molybdenum metal, several years after Scheele detected the presence of the new element in the molybdenum sulfide sample. <\/span><\/p>\n\n\n\n

First, Hjelm made a paste by mixing ground molybdic acid and carbon in linseed oil. After this step of the groundbreaking experiment, he exposed the mixture to red heat. The result was a pure metal form of the element 42.\u00a0<\/span><\/p>\n\n\n\n

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How Did Molybdenum Get Its Name?<\/span><\/h2>\n\n\n\n

The name of this chemical element originates from the Greek word ‘<\/span>molybdos<\/span><\/i>‘, meaning \u2018<\/span>lead<\/span><\/i>\u2019. This term was chosen for molybdenum because, in the past, a soft and black mineral labeled as <\/span>molybdenite<\/span><\/i> (or <\/span>molybdena<\/span><\/i>) was used in the making of pencils, instead of graphite. <\/span><\/p>\n\n\n\n

Since these two substances were found to be extremely similar, it was thought that the black mineral also contains lead<\/a>. Today we know that it was molybdenum disulfide (MoS2).\u00a0<\/span><\/p>\n\n\n\n

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Where Can You Find Molybdenum?<\/span><\/h2>\n\n\n\n

Despite being the 42nd most abundant element in the Universe, molybdenum cannot be found freely in nature in its pure, elemental form. It\u2019s mostly obtained from the mineral molybdenite (molybdenum disulfide, MoS<\/span>2<\/span>), lead molybdate, PbMoO<\/span>4<\/span> (wulfenite), and MgMoO<\/span>4<\/span>. <\/span><\/p>\n\n\n\n

Typically, the concentrated mineral molybdenite is exposed to high temperatures and air in order for molybdenum trioxide (MoO<\/span>3<\/span>, or technical molybdic oxide) to be produced for commercial purposes. After this, the derived substance undergoes purification and is reduced with hydrogen<\/a> to the metal form of molybdenum:<\/span><\/p>\n\n\n\n

MoO<\/b>3<\/b> + 3H<\/b>2<\/b> \u2192 Mo + 3H<\/b>2<\/b>O<\/b><\/p>\n\n\n\n

The powdery form of the molybdenum metal is produced by a hydrogen reduction of a chemically pure molybdic oxide or ammonium molybdate. Later, this powder is converted to solid metal by the process of arc-casting or by the powder-metallurgy process.<\/span><\/p>\n\n\n\n

Molybdenum can also be recovered as a by-product of tungsten and copper<\/a> mining. The United States, Chile, China, Peru, Mexico, and Canada are the world\u2019s largest producers of molybdenum metal for commercial purposes. Also, the largest mining sites are located in these countries.\u00a0\u00a0<\/span><\/p>\n\n\n\n

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Molybdenum in Everyday Life<\/span><\/h2>\n\n\n\n

This chemical element occurs as an essential part of many enzymes, such as nitrogenase and xanthine oxidase. The enzyme nitrogenase is responsible for turning the nitrogen into compounds that support the synthesis and utilization of proteins by the human body, the plants, as well as various types of bacteria, and all higher eukaryote organisms. <\/span><\/p>\n\n\n\n

Since protein metabolism is essential for all life forms, molybdenum plays a vital role in the synthesis of proteins. By being one of the essential trace elements found in the enzyme xanthine oxidase, molybdenum is directly responsible for the waste processing by the human body.<\/span><\/p>\n\n\n\n

Apart from being one of the essential trace elements for animals and plants, molybdenum plays a significant role as a catalyst in the industry. Thus, this chemical element has been included as one of the most vital agents in the following processes:<\/span><\/p>\n\n\n\n