The element represented by the symbol Na is sodium. Sodium is a distinct element on the periodic table, placed in Group 1 as an alkali metal. It is known for being highly reactive, especially with water, and is essential for various biological functions in living organisms. In its pure form, sodium is a soft, silvery-white metal that can be cut with a knife. It is commonly found in nature, primarily as sodium chloride (table salt), which is crucial for human health. Sodium plays a vital role in fluid balance, nerve transmission, and muscle function, making it an important element in biochemistry.