The Periodic Table

Sodium

Symbol: Na

Electron configuration: S1-2 S2-8, S3-1

Atomic mass: 22.989769 u ± 2 × 10^-8 u

Atomic number: 11

Melting point: 97.79 °C

Molar mass: 22.9898 g/mol

Boiling point: 882.8 °C

Sodium is a chemical element with symbol Na 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 that it readily donates, creating a positively charged atom—the Na+ cation. It's only stable isotope is 23Na.

Sodium was first isolated by Humphry Davy in 1807 by the electrolysis of sodium hydroxide. Among many other useful sodium compounds, sodium hydroxide is used in soap manufacture, and sodium chloride (edible salt) is a de-icing agent and a nutrient for animals including humans.

Sodium is an essential element for all animals and some plants. Sodium ions are the major cation in the extracellular fluid (ECF) and as such are the major contributor to the ECF osmotic pressure and ECF compartment volume. Loss of water from the ECF compartment increases the sodium concentration, a condition called hypernatremia. Isotonic loss of water and sodium from the ECF compartment decreases the size of that compartment in a condition called ECF hypovolemia.