| 释义 |
WordReference Random House Unabridged Dictionary of American English © 2024ru•bid•i•um (ro̅o̅ bid′ē əm),USA pronunciation n. [Chem.]- Chemistrya silver-white, metallic, active element resembling potassium, used in photoelectric cells and radio vacuum tubes. Symbol: Rb;
at. wt.: 85.47;
at. no.: 37;
sp. gr.: 1.53 at 20°C.
- Neo-Latin, equivalent. to Latin rūbid(us) red (in allusion to the two red lines in its spectrum) + -ium -ium
- 1860–65
Collins Concise English Dictionary © HarperCollins Publishers:: rubidium /ruːˈbɪdɪəm/ n - a soft highly reactive radioactive element of the alkali metal group; the 16th most abundant element in the earth's crust (310 parts per million), occurring principally in pollucite, carnallite, and lepidolite. It is used in electronic valves, photocells, and special glass. Symbol: Rb; atomic no: 37; atomic wt: 85.4678; half-life of 87Rb: 5 × 1011 years; valency: 1, 2, 3, or 4; relative density: 1.532 (solid), 1.475 (liquid); melting pt: 39.48°C; boiling pt: 688°C
Etymology: 19th Century: from New Latin, from Latin rubidus dark red, with reference to the two red lines in its spectrumruˈbidic adj |