Na keychain 20x40 mm.

<div>   </div> <div> <strong> Atomic number <span class = "Apple-tab-span" style = "white-space: pre;"> </span>         11 </strong> </div> <div> <strong> Atomic mass <span class = "Apple-tab-span" style = "white-space: pre"> </span>           22,990 </strong> </div> <div> <strong> Density, kg / m? <Span class = "Apple-tab-span" style = "white-space: pre"> </span>           970 </strong> </div> <div> <strong> Temperature </strong></div> <div> <strong> melting, ° С <span class = "Apple-tab-span" style = " white-space: pre "> </span>             97.8 </strong> </div> <div>   </div> <div> Sodium is a soft, silvery-white alkali metal. </div> <div> Natural sodium compounds - table salt, soda - have been known since ancient times. The name "Sodium" comes from the Arabic natrun, Greek. nitron, originally referred to as natural soda. Already in the 18th century, chemists knew many other sodium compounds. However, the metal itself was obtained only in 1807 by G. Davy by electrolysis of caustic soda. In the UK, USA, France, the element is called Sodium (from the Spanish word soda - soda), in Italy - sodio. & Nbsp; </div> <div> Metallic sodium is widely used as a strong reducing agent in preparative chemistry and industry, including metallurgy ... Used for drying organic solvents such as ether. Sodium is used in the production of highly energy-intensive sodium-sulfur batteries. It is also used in the exhaust valves of truck engines as a liquid heat sink. Occasionally, metallic sodium is used as a material for electrical wires designed for very high currents. </div> <div>   </div>