Sodium (Na)
Alkali metal · s-block · period 3 · group 1
Soft, silvery metal that can be cut with a knife; dulls instantly in air.
Sodium (symbol Na) is chemical element number 11, a alkali metal in group 1, period 3 of the periodic table. Its standard atomic weight is 22.990 and its electron configuration is [Ne] 3s1. At room temperature it is a solid. Reacts violently with water, fizzing and often bursting into yellow flame.
Properties
| Atomic number | 11 |
|---|---|
| Atomic mass | 22.990 |
| Category | Alkali metal |
| Block | s-block |
| Group · Period | 1 · 3 |
| Electron configuration | [Ne] 3s1 |
| Electrons per shell | 2, 8, 1 |
| State at 25 °C | solid |
| Melting point | 370.87 K |
| Boiling point | 1156 K |
| Density | 0.968 g/cm³ |
| Electronegativity (Pauling) | 0.93 |
| Radioactive | No |
| Origin | primordial |
| Discovered | 1807 · Humphry Davy |
Key facts about Sodium
- Reacts violently with water, fizzing and often bursting into yellow flame.
- Kept under kerosene or oil to keep air and moisture away.
- Every cell in your body uses sodium ions to carry electrical signals.
- Gives a strong persistent yellow colour to a flame — the basis of street lamps.
What Sodium is used for
Table salt and countless sodium compounds, street lighting, coolant in some nuclear reactors, chemical reducing agent.
Where it sits in the periodic table
Sodium is in group 1, period 3, of the s-block. Its electron configuration [Ne] 3s1 means its outermost shell holds 1 electron, which is what places it here and explains much of its chemistry. See Sodium on the interactive table →
Sodium — frequently asked questions
What is Sodium used for?
Table salt and countless sodium compounds, street lighting, coolant in some nuclear reactors, chemical reducing agent.
Is Sodium radioactive?
No. Sodium has at least one stable isotope and is not radioactive.
What is the electron configuration of Sodium?
Sodium has the electron configuration [Ne] 3s1, which is 2, 8, 1 electrons per shell.
What group and period is Sodium in?
Sodium is in group 1, period 3, in the s-block. Its outer shell holds 1 electron.
Who discovered Sodium?
Sodium was discovered in 1807 by Humphry Davy.