Platinum subject = Chemistry title = Platinum Platinum is a relatively rare, chemically inert, metallic element. It symbol is Pt, atomic number is 78, and its atomic weight is 195.09. Platinum is one of the heaviest substances known. One cubic foot of Platinum weighs 21 times as much as a cubic foot of water. A grayish-white metal, Platinum has a melting point of 1772 degrees C and a realatively high boiling point of 3827 degrees C.
It has a high fusing point, is ductile and malleable, expands slightly upon heating, and has high electrical resistance. Platinum is seldom used in its pure stage because it is too soft. The third most ductile metal, it can be drawn into a thread one twenty thousandth part of an inch in thickness. It is extremely resistant to attack by air, water, single acids and ordinary reagents, but does dissolve in hot aqua regia, a mixture of nitric and hydrochloric acids. Platinum has the unusual property of being able to absorb large amounts of hydrogen at ordinary temperatures and resist it at high temperatures.
The first mention of Platinum occurs in the writings of an Italian physician and poet named Julius Caesar Salinger in 1557. A hieroglypic character made froma grain of Platinum dated back to the 7th century. Credit for discovery of Platinum has been given to Don Antonio de Ulloa, a young lieutenant in the Spanish Navy. The metal was referred to as the “platina de Pinto”, meaning the siver like metal from the Pinto River. The first thorough study of Platinum was conductd in1750 by the English physician William Brownrigg.
Brownrigg noted that Platinum was heavier and even more chemically inert than Gold was. Platinum forms useful alloys with many other metals, including Iridium, Palladium, Rhodium, Ruthenium, Osmium, Gold, Nickel, Cobalt, and Tungsten. At high temperatures Platinum also reacts with Chlorine, Fluorine, Phosphorus, Arsenic and Sulfur. Among the transition metals, Platinum has the greatest tendencies to bond directly with Carbon. Platinum is used extensively in modern industrial society because of its chemical inertness, high melting point, and extraordinary catalytic properties. platinum is valuable for laboratory apparatus, such as tongs, combustion boats, crucibles and evaoporating dishes.
It is also used for thermometers in furnaces, for electrodes in making quantitative chemical analyses, and for corrosion and heat-resistant instruments. Platinum is used extensively in the jewelry industry for setting diamonds and other precious stones. Rocket and jet engine parts often contain Platinum alloys because they must withstand high temperatures for long periods of time. At petroleum refineries, finely divided Platinum is used as a catalyst in upgrading the octane of gasoline. In automobiles, converters containing Platinum-Palladium alloys reduce air pollution from exhaust gases.
High quality optical glass for television picture tubes and eyeglasses is melted in pots lined with nonreactive Platinum alloys. A form of Platinu m,cisplatin, stops cancer cell division and disrupts its growth pattern.