potasium

     

Potassium (pronounce /pəˈtæsiəm/) is a chemical element. It has the symbol K (Latin: kalium) and atomic number 19. The name "potassium" comes from the word "potash", as potassium was first isolated from potash. Potassium is a soft silvery-white metallic alkali metal that occurs naturally bound to other elements in seawater and many minerals. It oxidizes rapidly in air and is very reactive with water, generating sufficient heat to ignite the evolved hydrogen. In many respects, potassium and sodium are chemically similar, although they have very different functions in organisms in general, and in animal cells in particular.