ELEMENTLE

Element 4 · Alkaline Earth Metal

Beryllium

Period 2 · Group 2

Beryllium is a chemical element with symbol Be and atomic number 4. It is created through stellar nucleosynthesis and is a relatively rare element in the universe. It is a divalent element which occurs naturally only in combination with other elements in minerals.

Three reasons Beryllium stands out

  1. 1

    Often used in things that fly.

  2. 2

    Despite being lightweight, it is stiffer than steel.

  3. 3

    X-rays pass through it so easily that it is used as a window material in X-ray machines.

Light, stiff, and unforgiving

Beryllium combines low mass with remarkable stiffness, so small amounts strengthen aerospace structures and precision instruments. It barely absorbs X-rays, making thin beryllium windows useful in detectors. The same element demands strict handling, because inhaled beryllium dust can cause serious chronic lung disease.

Beryllium at a glance
Atomic number / protons4
SymbolBe
Family (Elementle)Alkaline Earth Metal
Classification (PubChem)Alkaline earth metal
Period2
Group2
Atomic mass (u)9.012183
Standard stateSolid
Electron configuration[He]2s2
Reported oxidation states+2
Electronegativity (Pauling)1.57
Atomic radius (pm)153
First ionization energy (eV)9.323
Electron affinity (eV)Not available
Density (g/cm³)1.85
Melting point1560 K (1,286.85 °C)
Boiling point2744 K (2,470.85 °C)
Discovery (PubChem)1798

Values are reference data, not a specification for every temperature, pressure, or allotrope. Unknown properties are left unavailable. Superheavy-element predictions remain uncertain.

Sources & further reading

PubChem: Beryllium · Beryllium on Wikipedia

The introduction and original editorial story are adapted from Wikipedia contributors via Periodic-Table-JSON. Element descriptions and their adaptations are available under CC BY-SA 3.0. Numerical attributes use the PubChem periodic-table dataset, retrieved September 22, 2026.