rubidium
noun/ruːˈbɪdiəm/
/ruːˈbɪdiəm/
[uncountable] (symbol Rb)
- a chemical element. Rubidium is a rare soft silver-coloured metal that reacts strongly with water and burns when it is brought into contact with air.Word Originmid 19th cent.: modern Latin, from Latin rubidus ‘red’ (with reference to its spectral lines).
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rubidium