What is osmium?


The osmium is a chemical element located in the group of metals of platinum Groups 8-10 (VIIIb), periods 5 and 6 of the periodic table and is considered the element naturally more dense earth. It is a gray-white metal, very hard and strong, difficult to work with, even at high temperatures. Of platinum metals is the point of merging more high , so that melt it is very difficult. The alloys obtained from osmium are very resistant and must be treated before carrying out work with it because in its pure state it cannot be modified, for this reason it must be melted or madedust .


  • Symbol : Os
  • Atomic number : 76
  • Group:  8

What is osmium?

The osmium is a chemical element in the form of metal located in groups 8 to 10 of the periodic table. It is considered as the densest and hardest element on earth, so much so that in order to work with it it must first be melted or crushed .

  • Osmium characteristics
  • History
  • Who discovered osmium
  • Properties
  • What is it for
  • Where is it located

Osmium characteristics

  • Its name, symbol and atomic number respectively are: Osmium, Os, 76.
  • Its  atomic mass  is 190.23 u.
  • Its electronic configuration is: [Xe] 4f145d66s.
  • It is a slightly acidic oxide .
  • It is usually found in a solid state .
  • Its melting point is: 3306 K (3033 ° C) and its boiling point is: 5285 K (5012 ° C).
  • Its enthalpy of vaporization is: 627.6 kJ / mol and its enthalpy of fusion is : 31.8 kJ / mol.
  • It has an electrical conductivity of: 10.9 · 106 S / m.
  • It is greyish- white in color, hard, and quite shiny.
  • Its atomic number is 76.
  • It is the densest element of all those that exist with a weight of 22.6 g / cm3.
  • It is a not very active element and very stable from the chemical point of view.
  • When in its pure form it is not used, it is used in alloys as a platinum hardener and as a kind of catalyst.


It was discovered by the British chemist Smithson Tennant in 1803. At that time, osmium and iridium were identified in the black residue that remains after dissolving platinum mineral with water, a mixture of 25% nitric acid (HNO3) and 75 % Acid Hydrochloric Acid (HCl). Osmium comes from the Greek term osme , which means smell and odor.

Who discovered osmium

Smithson Tennant  discovered it in 1803.


The alloys that can be obtained through the union of osmium with other elements such as rhodium, ruthenium , iridium or platinum are used in the manufacture of fountain pens, compass tips , phonograph needles , electrical contacts and instrument pivots. They are used in the creation of these materials due to the extreme hardness of this element and its great resistance to corrosion . Osmium tetroxide, OsO4, is highly toxicFor people, concentrations in the air as low as 10-7 g / m3 can cause lung congestion, skin damage, and serious eye damage, for this reason it should only be handled by suitably qualified chemists . It is prepared by quite complex chemical processes from platinum ores in which it is found in a very small proportion and as a by-product in the osmium-rich ores of nickel and copper ores.

What is it for

  • It can be used as a hardening additive in alloys. When alloy is made with platinum, it is used for measurement and weight standards.
  • The main use of the metal is in the osmiridium alloy used for the manufacture of tips, pivots, etc.
  • The manufacture of alloys of great hardness with other elements of the platinum group is frequently used in the manufacture of ballpoint pens.
  • Osmium alloys are used in electrical contacts where high resistance is required.
  • Red-hot it oxidizes in air to form osmium tetroxide, OsO4, and reacts with fluorine and alkalis.
  • It forms salts with valences between +1 and +8.
  • It is used in the manufacture of incandescent filaments and as a catalyst, and one of its derivatives is used as a fixative in the field of histology.
  • It is used to produce very hard alloys, with other metals from the platinum subgroup,
  • Osmium tetroxide is also widely used in fingerprint detection and staining of fatty tissues for microscopy.

Where is it located

This element can be obtained in sands that contain platinum , iridium and a small amount of other metals. After carrying out an extensive process of enrichment of the sands, it is treated with aqua regia, and in this way platinum is obtained. It must then be separated from ruthenium by reduction with alcohols and precipitated in the form of OsO4. Purification is carried out by means of distillation .

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