sodiu

Sodium, known as sodiu in Romanian, is a chemical element with the symbol Na and atomic number 11. It is a soft, silvery‑white metal that belongs to the alkali metals in group 1. Sodium is highly reactive, especially with water, and is typically stored under oil or in an inert atmosphere to prevent oxidation. In nature it does not occur free due to its reactivity; instead it is found in compounds such as sodium chloride in seawater and in rock salt deposits. The most abundant natural isotope is Na-23.

Occurrence and production: Sodium is widespread in the Earth's crust, mainly as sodium chloride (halite) and other salts, and in minerals such as feldspars. It is produced industrially by electrolysis of molten sodium chloride (the Downs process) or by reduction of sodium compounds. It is stored under oil or inert gas because it reacts with air and moisture.

Uses: In food, sodium chloride is used for seasoning and preservation. In industry, sodium hydroxide (caustic soda), sodium carbonate (soda ash), and sodium bicarbonate (baking soda) are foundational chemicals. Sodium vapor lamps provide bright lighting. Elemental sodium is used in certain chemical processes and metallurgy.

Biology: Sodium ions are essential electrolytes in animals and humans, crucial for fluid balance, nerve impulses, and muscle function. The kidneys regulate sodium levels; excessive intake is linked to hypertension in some individuals.

History and nomenclature: Sodium was isolated in 1807 by Humphry Davy through electrolysis of molten caustic soda. The name sodium derives from Latin natrium, and the symbol Na from natrium. In Romanian, the element is called sodiu.