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.
According to our friends at WIKI pedia these are the metals that react to water this way:
www.nikechristo.com reacts with water and reacts explosively. :P
Alkali metals such as sodium, potassium
Cs
mecury
lithium
helium
Chlorine & other halogens.
Cesium is, except for Francium, the most reactive element of the alkaline metals. It explodes in water because it rapidly evolves Hydrogen gas and heat. The explosion results from the hydrogen gas blowing the boiling water out of the container and then igniting.
It explodes actually.
mecury
Sodium when placed in water explodes.
chlorine
lithium
helium
For example hydrogen.
sodium, combined with chlorine, it makes salt, but in pure form, it explodes in water
Sodium fluoride.
Flourine is the element.It is added as flouride ions.
Chlorine & other halogens.
Fluoride