Potassium is a chemical element with the symbol K and atomic number 19. It belongs to the alkali metal group of the periodic table. Potassium is a soft, silvery-white metal that reacts vigorously with water, producing hydrogen gas. It is highly reactive due to its position in the alkali metal group, and it readily forms compounds with other elements.

In biological systems, potassium plays a crucial role as an electrolyte, maintaining the balance of fluids within cells and helping with nerve impulse transmission, muscle contraction, and heart function. Adequate potassium intake is essential for maintaining proper cellular function and overall health.

Dietary sources of potassium include bananas, oranges, potatoes, spinach, and various other fruits, vegetables, and legumes. It is an essential nutrient for human health, and a deficiency or excess of potassium can have adverse effects on the body.