单词 | platinum |
释义 | platinum[ plat-n-uhm, plat-nuhm ] / ˈplæt n əm, ˈplæt nəm / SEE SYNONYMS FOR platinum ON THESAURUS.COM nounChemistry. a heavy, grayish-white, highly malleable and ductile metallic element, resistant to most chemicals, practically unoxidizable except in the presence of bases, and fusible only at extremely high temperatures: used for making chemical and scientific apparatus, as a catalyst in the oxidation of ammonia to nitric acid, and in jewelry. Symbol: Pt; atomic weight: 195.09; atomic number: 78; specific gravity: 21.5 at 20°C. a light, metallic gray with very slight bluish tinge when compared with silver. adjectivemade of platinum. (of an audio recording) having sold a minimum of one million copies. Origin of platinum1805–15; <New Latin, alteration of earlier platina <Spanish; see platina Words nearby platinumplatinocyanide, platinoid, Platinol, platinotype, platinous, platinum, platinum black, platinum-blond, platinum blonde, platinum disc, platinum metal Dictionary.com UnabridgedBased on the Random House Unabridged Dictionary, © Random House, Inc. 2020 Example sentences from the Web for platinumBritish Dictionary definitions for platinumplatinum / (ˈplætɪnəm) / nouna ductile malleable silvery-white metallic element, very resistant to heat and chemicals. It occurs free and in association with other platinum metals, esp in osmiridium: used in jewellery, laboratory apparatus, electrical contacts, dentistry, electroplating, and as a catalyst. Symbol: Pt; atomic no: 78; atomic wt: 195.08; valency: 1–4; relative density: 21.45; melting pt: 1769°C; boiling pt: 3827±100°C
Word Origin for platinumC19: New Latin, from platina, on the model of other metals with the suffix -um Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012 Medical definitions for platinumplatinum [ plăt′n-əm ] n. Symbol PtA ductile malleable metallic element usually occurring mixed with other metals such as iridium, osmium, or nickel and used as a catalyst and in dentistry. Atomic number 78. The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company. Scientific definitions for platinumplatinum [ plăt′n-əm ] PtA soft, ductile, malleable, silver-white metallic element that usually occurs with osmium, iridium, palladium, or nickel. It has a high melting point and does not corrode in air. Platinum is used as a catalyst and in making jewelry, electrical contacts, and dental crowns. Atomic number 78; atomic weight 195.08; melting point 1,772°C; boiling point 3,827°C; specific gravity 21.45; valence 2, 3, 4. See Periodic Table. The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved. |
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