[roo-bid-ee-uh
m] 
| a silver-white, metallic, active element resembling potassium, used in photoelectric cells and radio vacuum tubes. Symbol: Rb; atomic weight: 85.47; atomic number: 37; specific gravity: 1.53 at 20°C. |
| ru·bid·i·um (rōō-bĭd'ē-əm) n. Symbol Rb A soft silvery-white metallic element of the alkali group that ignites spontaneously in air and reacts violently with water, used in photocells and in the manufacture of vacuum tubes. Atomic number 37; atomic weight 85.47; melting point 38.89°C; boiling point 688°C; specific gravity (solid) 1.532; valence 1, 2, 3, 4. See Table at element. [From Latin rūbidus, red; see reudh- in Indo-European roots.] |
rubidium ru·bid·i·um (r&oomacr;-bĭd'ē-əm)
n.
Symbol Rb
A soft metallic element of the alkali group. Atomic number 37; atomic weight 85.47; melting point 39.31°C; boiling point 688°C; specific gravity (solid) 1.532; valence 1, 2, 3, 4.
rubidium
chemicalchemical element of Group 1 (also called Group Ia) in the periodic table, the alkali metal group. Rubidium is the second most reactive metal and is very soft, with a silvery-white lustre. A brief treatment of rubidium follows. For full treatment, see alkali metal.
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