K is the chemical symbol for potassium. Potassium comes from the English word potash. Potash was derived from the Mediaeval Latin word kalium; hence the K. Potassium, which has the atomic number of 19, is a silvery-white flaky metal that forms potassium peroxide when exposed to oxygen. Potassium is an essential mineral for our bodies, as it helps with balance, muscle contractions, and assists with nerve signals. Furthermore, high potassium can decrease your risk for stroke, lower your blood pressure, and prevent osteoporosis and kidney stones. Luckily, high potassium is found in many foods including bananas, oranges, cantaloupe, apricots, and grapefruit.