Sodium

File:Na-D-sodium D-lines-589nm.jpg

Sodium D-lines at 589 nm

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Sodium flame test

Sodium chloride polyhedra

Sodium stearate

Monensin

Phase diagram of potassium and sodium

Sodium is a chemical element with the symbol Na (from Latin natrium) and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 of the periodic table, because it has a single electron in its outer shell, which it readily donates, creating a positively charged ion—the Na⁺ cation. Its only stable isotope is ²³Na.

Characteristics

Sodium at standard temperature and pressure is a soft metal that can be readily cut with a knife. Freshly exposed sodium has a bright, silvery luster that rapidly tarnishes, forming a white coating of sodium hydroxide and sodium carbonate.

Occurrence

Sodium is the sixth most abundant element in the Earth's crust and exists in numerous minerals such as feldspar, sodium chloride, and soda niter.

Applications

Sodium compounds are of immense commercial importance, being particularly central to industries producing glass, paper, soap, and textiles.

Biological role

Sodium ions are essential for nerve and muscle function and are involved in the regulation of fluids in the body. Sodium also plays a key role in heart function and metabolic signaling.

See also

• Sodium in biology
• Sodium chloride
• Sodium bicarbonate
• Sodium hydroxide