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
Effective atomic number possible to obtain a much more accurate single-valued Z by weighting against the spectrum of the source. The effective atomic number for electron interactions may be calculated with a similar approach; see for instance Taylor "et al." 2009 and Taylor 2011. The cross-section based approach for determining Z is obviously much more complicated than the simple power-law approach described above, and this is why freely-available software has been developed for such calculations (Taylor "et al." 2012). Effective atomic number Effective atomic number has two different meanings: one that is the effective nuclear charge of an atom, and one that calculates