Potassium (K), chemical element of Group 1 (Ia) of the periodic table, the alkali metal group, indispensable for both plant and animal life. Potassium was the first metal to be isolated by electrolysis, by the English chemist Sir Humphry Davy, when he obtained the element (1807) by decomposing molten potassium hydroxide (KOH) with a voltaic battery. Potassium metal is soft and white with a silvery luster, has a low melting point, and is a good conductor of electricity. Continue reading from Encyclopedia Britannica
Potassium salts in the form of saltpetre (potassium nitrate, KNO3), alum (potassium aluminium sulfate, KAl(SO4)2), and potash (potassium carbonate, K2CO3) have been known for centuries. They were used in gunpowder, dyeing, and soap making. They were scraped from the walls of latrines, manufactured from clay and sulfuric acid, and collected as wood ash respectively. Reducing them to the element defeated the early chemists and potassium was classed as an ‘earth’ by Antoine Lavoisier. Then in 1807, Humphry Davy exposed moist potash to an electric current and observed the formation of metallic globules of a new metal, potassium. He noted that when they were dropped into water they skimmed around on the surface, burning with a lavender-coloured flame. Continue reading from Royal Society of Chemistry
About 2.4 percent of the mass of Earth's crust is potassium, including billions of tons of potassium chloride. Saltpeter (potassium nitrate) was used to preserve food in the Middle Ages and is part of gunpowder, which was invented in ninth-century China. Because it's so reactive, potassium isn't found free in nature, according to the Jefferson National Linear Accelerator Laboratory. However, minerals and compounds containing potassium are common: It's the seventh-most abundant element in Earth's crust. Potassium is also a necessary nutrient for life; as an electrolyte, it conducts electric signals in the body; along with sodium, it's crucial for proper muscle contraction. Continue reading from LiveScience
