Adjacent Words

Platinum definitions

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Webster's 1828 Dictionary

PLATI'NUM, n. A metal discovered in the mines of Choco in Peru, nearly of the color of silver, but less bright, and the heaviest of the metals. Its specific gravity is to that of water as 23 to 1. It is harder than iron, undergoes no alteration in air, resists the action of acids and alkalies, is very ductile and capable of being rolled into thin plates.

WordNet (r) 3.0 (2005)

n
1: a heavy precious metallic element; grey-white and resistant to corroding; occurs in some nickel and copper ores and is also found native in some deposits [syn: platinum, Pt, atomic number 78]

Merriam Webster's

I. noun Usage: often attributive Etymology: New Latin, from Spanish platina, from diminutive of plata silver — more at plate Date: 1808 1. a precious grayish-white noncorroding ductile malleable heavy metallic element that fuses with difficulty and is used especially in chemical ware and apparatus, as a catalyst, and in dental and jewelry alloys — see element table 2. a moderate gray II. adjective Date: 1971 qualifying for a platinum record

Britannica Concise

Metallic chemical element, one of the transition elements, chemical symbol Pt, atomic number 78. A very heavy, silvery-white precious metal, it is soft and ductile, with a high melting point (3,216° F, or 1,769° C) and good resistance to corrosion and chemical attack. Small amounts of iridium are commonly added for a harder, stronger alloy that retains platinum's advantages. Platinum is usually found as alloys of 80-90% purity in placer deposits, or more rarely combined with arsenic or sulfur. It is indispensable in high-temperature laboratory work, for electrodes, dishes, and electrical contacts that resist chemical attack even when very hot. Platinum is used in dental alloys, and surgical pins. Known as "white gold," it is used in expensive jewelry and is far more costly than gold. The international primary standards for weight and length are 90% platinum, 10% iridium. An alloy of 76.7% platinum and 23.3% cobalt forms the most powerful permanent magnets known. Platinum has valence 2 or 4 in its compounds, which include many coordination complexes. It and some compounds are useful catalysts, particularly for hydrogenation and in catalytic converters.

Dictionary of the Elements

platinum
Symbol: Pt
Atomic number: 78
Atomic weight: 195.078
Attractive greyish-white metal. When pure, it is malleable and ductile. Does not oxidize in air, insoluble in hydrochloric and nitric acid. Corroded by halogens, cyandies, sulphur and alkalis. Hydrogen and oxygen react explosively in the presence of platinum. There are six stable isotopes and three radioisotopes, the most stable being Pt-193 with a half-life of 60 years. Platinum is used in jewelry, laboratory equipment, electrical contacts, dentistry, and anti-pollution devices in cars. PtCl2(NH3)2 is used to treat some forms of cancer. Platinum-{cobalt} alloys have magnetic properties. It is also used in the definition of the Standard Hydrogen Electrode. Discovered by Antonio de Ulloa in South America in 1735. The name comes from the Spanish word platina which means silver. Platinum metal is generally not a health concern due to its unreactivity, however platinum compounds should be considered highly toxic.

Oxford Reference Dictionary

n. Chem. a ductile malleable silvery-white metallic element occurring naturally in nickel and copper ores, unaffected by simple acids and fusible only at a very high temperature, used in making jewellery and laboratory apparatus. Usage: Symb.: Pt. Phrases and idioms: platinum black platinum in powder form like lampblack. platinum blonde (or blond) adj. silvery-blond. --n. a person with silvery-blond hair. platinum metal any metallic element found with and resembling platinum e.g. osmium, iridium, and palladium. Etymology: mod.L f. earlier platina f. Sp., dimin. of plata silver

Webster's 1913 Dictionary

Platinum Plat"i*num, n. [NL., fr. Sp. platina, from plata silver, LL. plata a thin plate of metal. See Plate, and cf. Platina.] (Chem.) A metallic element, intermediate in value between silver and gold, occurring native or alloyed with other metals, also as the platinum arsenide (sperrylite). It is heavy tin-white metal which is ductile and malleable, but very infusible, and characterized by its resistance to strong chemical reagents. It is used for crucibles, for stills for sulphuric acid, rarely for coin, and in the form of foil and wire for many purposes. Specific gravity 21.5. Atomic weight 194.3. Symbol Pt. Formerly called platina. Platinum black (Chem.), a soft, dull black powder, consisting of finely divided metallic platinum obtained by reduction and precipitation from its solutions. It absorbs oxygen to a high degree, and is employed as an oxidizer. Platinum lamp (Elec.), a kind of incandescent lamp of which the luminous medium is platinum. See under Incandescent. Platinum metals (Chem.), the group of metallic elements which in their chemical and physical properties resemble platinum. These consist of the light platinum group, viz., rhodium, ruthenium, and palladium, whose specific gravities are about 12; and the heavy platinum group, viz., osmium, iridium, and platinum, whose specific gravities are over 21. Platinum sponge (Chem.), metallic platinum in a gray, porous, spongy form, obtained by reducing the double chloride of platinum and ammonium. It absorbs oxygen, hydrogen, and certain other gases, to a high degree, and is employed as an agent in oxidizing.

Collin's Cobuild Dictionary

1. Platinum is a very valuable, silvery-grey metal. It is often used for making jewellery. 2. Platinum hair is very fair, almost white. ...a platinum blonde with thick eye shadow and scarlet lipstick. COLOUR