The difference between potassium and sodium was discovered only in the 18th century. “Vegetable alkali” also known as potassium carbonate came from the earth. The “alkali minerals” also known as sodium carbonate came from wood ashes. Early chemists did not recognize that these were two different chemical compounds. Sir Humphry Davy discovered potassium in 1807 in England, isolating it by electrolysis. Potassium was the first metal to be isolated by electrolysis. The name potassium comes from the English word "potash" meaning pot ash and the Arabic word "qali" meaning alkali. This is because potassium was originally obtained by soaking wood ash in water and then evaporating the mixture in an iron pot. The origin of the element symbol “K” comes from the Latin word "kalium" which means potassium. Potassium was called kalium, so the symbol for the element is "K". Potassium is an "alkali metal" and a solid element. Alkali metals are very reactive metals that do not occur freely in nature. They are soft, malleable and good conductors of heat and electricity. It is the 19th element of the periodic table and is found in group 1, period 4. Potassium is very reactive and is never found free in nature. It is the eighth most abundant element on earth and makes up about 2.1% of the earth's crust. Potassium is obtained from the minerals sylvite, carnallite, langbeinite, alunite and polyhalite. These minerals are mainly found in seabeds and ancient lakes. Potassium is also found in caustic potash. Caustic potash is mined primarily in Germany, New Mexico, California, and Utah. The annual world production of potassium is approximately 200 tonnes. The main mining areas for potassium are Germany, Spain, Canada, the United States and Italy. When potassium...... middle of paper...... m to survive. Potassium is one of the three primary nutrients required by plants. Potassium works with sodium to aid in the digestion of food and the functioning of the eyes. People whose diet is low in potassium can develop hypokalemia, which in severe cases can be life-threatening. Symptoms include irregular heartbeat, fatigue, muscle cramps and constipation. It's unusual for people to be deficient in potassium just because they get too little of it in their diet, and it's usually caused by other ongoing problems in the digestive system. There are few uses of potassium as a pure element due to its highly reactive nature. During handling, complete skin and eye protection is required and, in most cases, an explosion-resistant barrier between the user and the metal. In the United States potassium chloride is used for executions by lethal injection.