The reactivity of rubidium might surprise you. In fact, rubidium is one of the most reactive of all the metals in the world. It catches fire when exposed to oxygen in the air, and burns up with a bright pinkish purple flame to become a yellow powder called rubidium superoxide.
If you try to put out the fire with water, it will only make matters worse. Want to know why? Rubidium reacts vigorously with water as well! When exposed to water, it produces hydrogen gas, which catches fire and burns.
By now, you would have understood why it is difficult to store rubidium. Most of the containers are not suitable for preserving or storing rubidium. If you place it in an ordinary glass container, the rubidium will destroy the glass at high temperatures. The only solution is to store it in special glass tubes in which a vacuum is maintained, or in flasks of kerosene or paraffin oil.
The name ‘rubidium’ comes from the term ‘rubidus’, which was a word once used to refer to the deepest red.
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