(n.) A rare metallic element. It occurs quite widely, but in small quantities, and always combined. It is isolated as a soft yellowish white metal, analogous to potassium in most of its properties. Symbol Rb. Atomic weight, 85.2.
Webster's Revised Unabridged Dictionary
| APA | Webster's. (2011). rubidium. Retrieved September 22, 2026, from http://smartdefine.org/rubidium/definitions/2056870 |
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| MLA | Webster's. "rubidium" 28 May 2011. Web. 22 September 2026. <http://smartdefine.org/rubidium/definitions/2056870> |