About

Beryllium is a relatively rare, lightweight, and exceptionally strong steel-gray metal. It enhances the properties of many alloys, especially with copper, and is used in demanding aerospace, defense, and medical applications like X-ray windows. It is found in precious gemstones like beryl (aquamarine, emerald), which gives it its name. Beryllium dust is toxic if inhaled.

Atomic Properties

Atomic Number4

Atomic Weight9.012 u

Neutrons (common)5

Electron Configuration[He] 2s²

Full Configuration1s² 2s²

Electrons per Shell2, 2

Electronegativity1.57

Electron Affinity0 kJ/mol

Oxidation States+2

Covalent Radius96 pm

Ionic Radius45 pm

Periodic Table Position

Group2

Period2

BlockS

Chemical SeriesAlkaline earth metals

Physical Properties

State at STPsolid

AppearanceHard, lightweight, steel-gray metal.

Crystal Structurehcp

Magnetic Orderingdiamagnetic

Speed of Sound12,890 m/s

Poisson Ratio0.032

Thermal Properties

Melting Point1,560 K

Boiling Point2,742 K

Thermal Expansion0 1/K

Thermal Conductivity200 W/(m·K)

Specific Heat1.825 J/(g·K)

Molar Heat16.443 J/(mol·K)

Heat of Fusion7.95 kJ/mol

Heat of Vaporization297 kJ/mol

Abundance

In Earth's Crust2.8 ppm

In Ocean0 ppm

In Solar System0 ppm

In Human Body0.001 ppm

In Universe0.001 ppm

Discovery

Discovered byLouis Nicolas Vauquelin

Discovery Year1,798

Occurrenceprimordial

CAS Number7440-41-7

Electron Configuration

Energy

↿⇂

Isotopes of Beryllium

Symbol ▲	Mass (u) ▲	Abundance ▲	Half-life ▲	Decay Mode ▲
⁷Be	7.016929	—	53.22 d	Electron Capture
⁹Be	9.012182	100%	Stable	Stable
¹⁰Be	10.013534	Trace	1.51 My	Beta Minus Decay

Interactive Visualization

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

View 3D Model of Beryllium