In the periodic table, NA stands for sodium. Sodium is a highly reactive alkali metal with the atomic number 11. It is essential for various biological processes, including nerve transmission and muscle contraction, playing a key role in maintaining fluid balance in the body. Sodium is commonly found in nature, primarily in salt (sodium chloride), which is fundamental in human diets. Due to its reactivity, sodium is usually stored under oil or in inert gases to prevent it from reacting with moisture or oxygen. Its applications extend beyond nutrition, as sodium compounds are used in various industrial and chemical processes.