Osmium

Osmium (chemical symbol: Os, atomic number: 76) is a chemical element belonging to the platinum group metals. It is a hard metal with a bluish-white color and luster, and is known to be one of the densest elements found in nature. Its density is approximately 22.6 grams per cubic centimeter, equal to or greater than that of iridium.

Osmium occurs naturally in association with other platinum group metals, particularly in platinum and nickel ores. It is extracted as a byproduct in the refining process of platinum metals. The annual production quantity is very small compared to other commercially significant metals.

Physical and chemical properties

Osmium is extremely hard and brittle even when heated. Its melting point and boiling point are exceptionally high. When powdered osmium comes into contact with air, it forms osmium tetroxide (OsO₄), a volatile substance with a strong odor that is harmful to the eyes and respiratory system. For this reason, work with osmium powder requires ventilation and precautions.

Applications

Its main use is in alloys combined with iridium or platinum to produce extremely hard and wear-resistant materials. It has been used in the tips of fountain pens, electrical contacts, and instruments requiring high precision. Osmium tetroxide is also used in biology to stain cells for microscopic observation, and as a catalyst in certain chemical reactions.

History

Osmium was identified in the early nineteenth century, discovered in the residue left behind when platinum ore was dissolved in aqua regia. Its name derives from the Greek word for 'odor,' referring to the sharp odor of its oxide.