What element explodes when added to water?

There are several elements that explode in water. The most commonly known ones are a particular group of metals. They are listed in ascending order of explosiveness. Lithium (Li), Sodium (Na), Potassium (K), Rubidium (Rb), Caesium (Cs) and Francium (Fr). The last of these;Francium, is so uncommon in nature that there is only an estimated 30g in the entire of the earth's crust.