Sodium (chemical symbol - Na, from Lat. Natrium) is a chemical element of the 1st group (according to the outdated classification - the first group of the main subgroup, IA), the third period of the periodic system of chemical elements of D. I. Mendeleev, with atomic number 11.
In the form of a simple substance, sodium is a very light (0.971 g /cm3), soft alkaline metal of silver-white color. At the external energy level, sodium has one electron, which it easily gives away, turning into a positively charged Na+ cation.
The only stable natural isotope of sodium is 23Na.
It does not occur in free form in nature, but can be obtained from various compounds. Sodium is the sixth most common element in the earth's crust: it is found in numerous minerals, including feldspar, sodalite and "rock salt" (halite, sodium chloride).
