| 释义 |
WordReference Random House Learner's Dictionary of American English © 2024i•rid•i•um /ɪˈrɪdiəm/USA pronunciation n. [uncountable]- Chemistrya precious metal resembling platinum.
WordReference Random House Unabridged Dictionary of American English © 2024i•rid•i•um (i rid′ē əm, ī rid′-),USA pronunciation n. [Chem.]- Chemistrya precious metallic element resembling platinum: used in platinum alloys and for the points of gold pens. Symbol: Ir;
at. wt.: 192.2;
at. no.: 77;
sp. gr.: 22.4 at 20°C.
- Latin īrid-, stem of īris rainbow (see iris) + -ium; so named from its iridescence when dissolved in hydrochloric acid
- 1804
Collins Concise English Dictionary © HarperCollins Publishers:: iridium /aɪˈrɪdɪəm ɪˈrɪd-/ n - a very hard inert yellowish-white transition element that is the most corrosion-resistant metal known. It occurs in platinum ores and is used as an alloy with platinum. Symbol: Ir; atomic no: 77; atomic wt: 192.22; valency: 3 or 4; relative density: 22.42; melting pt: 2447°C; boiling pt: 4428°C
Etymology: 19th Century: New Latin, from irido- + -ium; from its colourful appearance when dissolving in certain acids |