Sodium (symbol Na, atomic number 11) is a soft, highly reactive metal whose ion is half of common table salt. It is classified as a alkali metal and sits in group 1, period 3 of the periodic table.
Overview
Sodium is the chemical element with atomic number 11 and the symbol Na. With a standard atomic weight of 22.99, it is a alkali metal. In the periodic table it occupies group 1 and period 3, and under standard conditions it is normally a solid. Sodium is a soft, highly reactive metal whose ion is half of common table salt.
Atomic structure
An atom of Sodium has 11 protons in its nucleus and, when neutral, 11 electrons arranged in the configuration [Ne] 3s1. Its standard atomic weight of 22.99 reflects the natural mix of its stable isotopes.
Discovery and place in the table
Sodium was discovered in 1807 by Humphry Davy. It follows Neon (Ne) and precedes Magnesium (Mg) in order of atomic number.
| Atomic number | 11 |
|---|---|
| Symbol | Na |
| Atomic mass | 22.99 |
| Category | Alkali metal |
| Group | 1 |
| Period | 3 |
| Electron configuration | [Ne] 3s1 |
| Phase at STP | Solid |
| Discovered | 1807 (Humphry Davy) |