Potassium in 1809, Ludwig Wilhelm Gilbert proposed the name "Kalium" for Davy's "potassium". In 1814, the Swedish chemist Berzelius advocated the name "kalium" for potassium, with the chemical symbol "K". The English and French speaking countries adopted Davy and Gay-Lussac/Thénard's name Potassium, while the Germanic countries adopted Gilbert/Klaproth's name Kalium. The "Gold Book" of the International Union of Physical and Applied Chemistry has designated the official chemical symbol as K. Potassium is the second least dense metal after lithium. It is a soft solid with a low melting point, and can be easily cut with a knife. Freshly cut potassium is
Potassium pyrosulfate Potassium pyrosulfate Potassium pyrosulfate, or potassium disulfate, is an inorganic compound with the chemical formula KSO. Potassium pyrosulfate is obtained by the thermal decomposition of other salts, most directly from potassium bisulfate: Temperatures above 600°C further decompose potassium pyrosulfate to potassium sulfate and sulfur trioxide however: Other salts, such as potassium trisulfate, can also decompose into potassium pyrosulfate. Potassium pyrosulfate contains the pyrosulfate anion which has a dichromate like structure. The geometry can be visualized as a tetrahedron with two corners sharing the SO anion's configuration and a centrally bridged oxygen atom. A semi-structural formula for the pyrosulfate anion is