Potassium Potassium Potassium is a chemical element with symbol K (from Neo-Latin "kalium") 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. All of the alkali metals have a single valence electron in the outer electron shell, which is easily removed to create an ion with a positive charge – a cation, which combines with anions to form salts. Potassium in nature occurs only in ionic salts. Elemental potassium is a soft silvery-white alkali metal that oxidizes rapidly in air
Atomic number was seen as containing 118 neutrons rather than 118 nuclear electrons, and its positive charge now was realized to come entirely from a content of 79 protons. After 1932, therefore, an element's atomic number "Z" was also realized to be identical to the proton number of its nuclei. The conventional symbol "Z" possibly comes from the German word (atomic number). However, prior to 1915, the word "Zahl" (simply "number") was used for an element's assigned number in the periodic table. Each element has a specific set of chemical properties as a consequence of the number of electrons present in the