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 ferrioxalate Potassium ferrioxalate Potassium ferrioxalate, also known as potassium trisoxalatoferrate(III), is a chemical compound with the formula [], where iron is in the +3 oxidation state. It is an octahedral transition metal complex in which three bidentate oxalate ions are bound to an iron center. Potassium acts as a counterion, balancing the −3 charge of the complex. Crystals of the trihydrated form of the complex, []·3, are emerald green in color. In solution, the salt dissociates to give the ferrioxalate anion, [], which appears fluorescent green in color. Potassium ferrioxalate is often used in chemical actinometry, i.e. the measure of light