(3) Potassium is a chemical element with symbol K and atomic number 19. It was first isolated from potash, the ashes of plants,from which its name derives. In the periodic table, potassium is one of the alkali metals. It is a soft solid with a low melting point, and can be easily cut with a knife. Potassium has the lowest melting point among the given metals. Its melting point is 63.3C.