Potassium is the chemical component with the symbol K, atomic number 19, and atomic mass 39.0983. Potassium was first isolated from potash. Elemental potassium is a soft silvery-white metallic alkali metal that oxidizes quick in air and is very reactive with water.
Potassium is the second smallest dense metal; only lithium is less dense. It is a soft, low-melting solid that can simply be cut with a knife. Freshly cut potassium is silvery in form, but in air it begins to dull toward grey immediately.
Biological Application Potassium ions are an necessary component of plant nutrition and are originate in most soil types. Its primary use in agriculture, horticulture and hydroponic culture is as a fertilizer as the chloride (KCl), sulfate (K2SO4) or nitrate (KNO3).In animal cells, potassium ions are very important to keeping cells alive .