Sodium /ˈsoʊdiəm/ is a chemical element with symbol Na (from Ancient Greek Νάτριο) and atomic number 11. It is a soft, silver-white, highly reactive metal. In the Periodic table it is in column 1 (alkali metals), and shares with the other six elements in that column that it has a single electron in its outer shell, which it readily donates, creating a positively charged atom - a cation.
Three reasons Sodium stands out
- 1
Reacts violently with water.
- 2
Its vapour gives street lamps their characteristic warm yellow glow.
- 3
As an ion, it is essential for transmitting nerve impulses throughout the body.
A metal transformed by one electron
Sodium metal is soft, silvery, and violently reactive with water; sodium ions are stable enough to circulate through blood and seawater. That contrast comes from losing a single outer electron. In the body, controlled sodium-ion movement creates the electrical pulses used by nerves and muscles.