Sodium

**Symbol:** Na

**Atomic number:** 11

**International title:** natrium

**Relative Atomic Weight:** 22,99

**Information:** Sodium is a very reactive, glossy, light, very soft (can be cut by a knife) silver metal. There is a risk of self-ignition in the air, so it must be kept under a kerosene layer. It conducts very well electricity and heat. It exists in the form of a sodium cation Na⁺.

**Use:** It is used to remove heat (as a cooling medium) in nuclear power plants and aircraft engines. Its compound sodium hydroxide NaOH is one of the basic chemicals of the chemical industry.

**Occurrence:** Sodium is among the top ten most popular elements on Earth. It occurs only in the form of compounds. Among its most important minerals are NaCl (or salt), Chilean NaNO₃ and cryolite Na₃AlF₆. It is part of all living organisms (it is a biogenic element).

**Structure:** Sodium crystallizes into a cubic (cubic) system (spatially centered cell).