rubidium
/rʊˈbɪdɪəm
/noun [mass noun]
The chemical element of atomic number 37, a rare soft silvery reactive metal of the alkali metal group. (Symbol: Rb) Those that produce a measurable spectrum when subjected to flame include, but are not limited to, lithium, sodium, potassium, rubidium, cesium, magnesium, calcium, strontium, barium, zinc, and cadmium....
- These elements - lithium, sodium, potassium, rubidium, cesium and francium - all react with water to give solutions that change the color of a vegetable dye from red to blue.
- Elements such as rubidium, zirconium, and aluminum are mostly incorporated into human biochemistry as a consequence of their association with essential elements present in the human diet.
Origin
Mid 19th century: modern Latin, from Latin rubidus 'red' (with reference to its spectral lines).