The 11th element on the periodic table is sodium (Na). Sodium is a highly reactive, soft, silvery-white metal belonging to the alkali metals group. It has an atomic number of 11 and is known for its essential role in biological systems, particularly in nerve transmission and maintaining fluid balance in the body. Sodium commonly occurs in nature combined with other elements, primarily in the form of salts like sodium chloride (table salt). Due to its reactivity, sodium is not found in its pure form in nature and must be processed from compounds for various industrial and scientific applications.