Platinum

Descoperire și istorie

Platinum was known to pre-Columbian civilizations in South America, and the first documented mention of the metal was by Europeans in the 16th century. Spanish explorers encountered platinum in what is now Colombia, referring to it as 'platina,' meaning 'little silver.' However, it was not until the late 17th century that the metal was properly recognized in Europe. In 1735, the Swedish chemist Henrik Scheffer classified platinum as a unique element, while in 1783, the French chemist Antoine Lavoisier conducted experiments to demonstrate its elemental nature. The refinement techniques for obtaining platinum improved significantly in the 19th century, leading to its widespread use.

Răspândire în natură

Platinum is a rare element found in the Earth's crust at an estimated average concentration of 0.005 parts per million. It occurs naturally in a few nickel and copper ores and can be found in alluvial deposits, where erosion has liberated it from host rocks. Major deposits of platinum are situated in regions such as South Africa, Russia, and Canada. In these areas, it is often extracted from complex ores associated with other platinum group metals (PGMs). Due to its scarcity, platinum is considered one of the rarest metals in the world, making its extraction economically significant.

Rol biologic și importanță

Platinum does not have a known biological role in human or animal metabolism, as it is not an essential element for any living organism. However, certain platinum compounds have been utilized in medicine, particularly in chemotherapy treatments for cancer. Cisplatin, a platinum-based drug, is widely used to treat various forms of cancer, demonstrating that while platinum itself is not biologically necessary, its compounds can have crucial therapeutic applications.

Proprietăți fizice și chimice

Platinum is a silvery-white metal that is dense, malleable, and ductile, with a melting point of approximately 1,768 °C and a boiling point of about 3,830 °C. Its density is around 21.45 grams per cubic centimeter, making it one of the heaviest metals. Platinum is notable for its remarkable resistance to corrosion and oxidation, even at high temperatures, which contributes to its longevity in various applications. Chemically, platinum can exist in several oxidation states, commonly +2 and +4, and it forms various compounds with halogens and nonmetals. Its catalytic properties are highly valued in chemical reactions.

Utilizări și aplicații

Platinum is widely used in the jewelry industry due to its lustrous appearance and resistance to tarnish. Moreover, it is a critical component in the manufacture of catalytic converters in automotive vehicles, where it helps convert harmful gases into less toxic substances. In industry, platinum is utilized in the production of various chemicals, including nitric acid and silicone. Its usage extends to electronics, where it is employed in the production of high-quality connectors and as a catalyst in fuel cells for clean energy applications. Additionally, platinum is an essential material in certain medical devices and equipment.

Știai că?

• Platinum is often mixed with other metals, such as iridium or ruthenium, to create durable alloys suitable for demanding applications.
• The name 'platinum' comes from the Spanish word 'platina,' which means 'little silver.'
• Platinum has a much higher melting point than gold, making it more difficult to work with in jewelry manufacturing.
• The largest producer of platinum in the world is South Africa, accounting for about 75% of global supply.
• Cisplatin, a drug derived from platinum, was discovered by accident while studying cell division.