The term IT EXPLODES WHEN WET can be solved by the word 'SODIUM', which is a chemical element with the atomic number 11. It is a soft, silvery-white, highly reactive metal and is a member of the alkali metal group of chemical elements. SODIUM is an essential element for all animals and some plants, and it is the sixth most abundant element in the Earth's crust. When SODIUM comes into contact with water, it reacts vigorously and can cause explosions.