About

Sodium is a soft, silvery-white, highly reactive alkali metal that tarnishes instantly in air and reacts violently with water. It is essential for animal life, with the sodium-potassium pump being vital for nerve cell function. Its most common compound is sodium chloride (table salt). It's also used in sodium-vapor lamps for efficient streetlights and as a heat transfer agent in some nuclear reactors.

Atomic Properties

Atomic Number11

Atomic Weight22.99 u

Neutrons (common)12

Electron Configuration[Ne] 3s¹

Full Configuration1s² 2s² 2p⁶ 3s¹

Electrons per Shell2, 8, 1

Electronegativity0.93

Electron Affinity52.8 kJ/mol

Oxidation States+1

Covalent Radius154 pm

Van der Waals Radius227 pm

Ionic Radius102 pm

Periodic Table Position

Group1

Period3

BlockS

Chemical SeriesAlkali metals

Physical Properties

State at STPsolid

Appearancesilvery-white metal which tarnishes rapidly upon exposure to air

Crystal Structurebcc

Magnetic Orderingparamagnetic

Speed of Sound3,200 m/s

Poisson Ratio0.28

Thermal Properties

Melting Point370.944 K

Boiling Point1,156.09 K

Triple Point370.944 K

Thermal Expansion0 1/K

Thermal Conductivity140 W/(m·K)

Specific Heat1.228 J/(g·K)

Molar Heat28.23 J/(mol·K)

Heat of Fusion2.598 kJ/mol

Heat of Vaporization97.42 kJ/mol

Abundance

In Earth's Crust23,600 ppm

In Ocean10,800 ppm

In Solar System20.3 ppm

In Human Body1,400 ppm

In Universe20 ppm

Discovery

Discovered byHumphry Davy

Discovery Year1,807

Occurrenceprimordial

CAS Number7440-23-5

Electron Configuration

Energy

↿⇂

↿

Isotopes of Sodium

Symbol ▲	Mass (u) ▲	Abundance ▲	Half-life ▲	Decay Mode ▲
²²Na	21.994436	—	2.6019 y	Positron Emission, Electron Capture
²³Na	22.989769	100%	Stable	Stable
²⁴Na	23.990963	—	14.9560 h	Beta Minus Decay

Interactive Visualization

Explore the 3D Bohr model of Sodium in our interactive viewer.

View 3D Model of Sodium