The chemical element represented by the symbol Na is sodium. Sodium is an alkali metal and is found in Group 1 of the periodic table. It is highly reactive, especially with water, producing sodium hydroxide and hydrogen gas. In its natural form, sodium is usually found in various compounds rather than in its elemental state, as it readily reacts with other elements. It plays crucial roles in biological systems, particularly in nerve impulse transmission and fluid balance within cells. Sodium is also important in industry, being used in the production of several chemical compounds and in various applications.