Be
Beryllium
Element 4 · Alkaline earth metal
Beryllium (Be)
Beryllium is a light, stiff, steel-grey metal. It is transparent to X-rays, but its dust is highly toxic when inhaled.
- Alkaline earth metal
- Period 2
- Group 2
- s-block
- solid at room temperature
Key properties
- Atomic mass
- 9.0122
- u
- Electron configuration
- [He] 2s2
- Melting point
- 1,286.9 °C
- 1,560 K
- Boiling point
- 2,470.9 °C
- 2,744 K
- Density
- 1.85 g/cm³
- Electronegativity
- 1.57
- Pauling
- Atomic radius
- 153 pm
- van der Waals
- 1st ionisation energy
- 9.323 eV
Compare with every element:Electronegativity chartAtomic radius chartIonisation energy chartDensity chart of the elementsMelting point chartElectron configuration chart
Did you know?
Notable facts about beryllium
- 01
Emeralds and aquamarines are gem varieties of beryl, a beryllium aluminium silicate.
- 02
The James Webb Space Telescope’s 18 primary mirror segments are made of gold-coated beryllium.
- 03
Its compounds taste sweet, which gave it the early name “glucinium”.
Applications
What is beryllium used for?
- X-ray windows
- Aerospace and satellite structures
- Copper–beryllium spark-free tools
- Neutron reflectors in reactors
History
Discovery & name origin
Discovered by
Year
Where
France
Name origin
From the mineral beryl, whose name comes from Greek beryllos.
Atomic structure
Atomic properties
Atomic structure
Atomic properties
- Atomic number
- 4
- Atomic mass
- 9.0122 u
- Group
- 2
- Period
- 2
- Block
- s-block
- Electron configuration
- [He] 2s2
- Full configuration
- 1s2 2s2
- Electrons per shell
- 2, 2
- Electronegativity (Pauling)
- 1.57
- Electron affinity
- —
- Atomic radius (van der Waals)
- 153 pm
- Stable isotopes
- 1
Oxidation states
Highlighted: common oxidation states (+2).
Successive ionisation energies
Energy to remove each electron in turn (kJ/mol). Big jumps show where a new, inner shell begins.
- 1st899.5
- 2nd1,757.1
- 3rd14,848.7
- 4th21,006.6
Physical
Physical properties & colour
Physical
Physical properties & colour
- State at 20 °C
- Solid
- Melting point
- 1,560 K · 1,286.9 °C · 2,348.3 °F
- Boiling point
- 2,744 K · 2,470.9 °C · 4,479.5 °F
- Density
- 1.85 g/cm³
- Molar heat capacity
- 16.443 J/(mol·K)
- Appearance
- White-grey metallic
- CPK model colour
- Copied
The CPK colour is the convention used for this element’s atoms in molecular models.
FAQ
Beryllium questions
What is Be on the periodic table?
Be is the symbol for beryllium, element 4 on the periodic table. It sits in group 2, period 2, in the alkaline earth metal category, and has an atomic mass of 9.0122.
What is the atomic number of beryllium?
Beryllium has atomic number 4, so every beryllium atom has 4 protons in its nucleus. Its symbol is Be and its atomic mass is 9.0122.
Who discovered beryllium?
Beryllium was discovered by Louis-Nicolas Vauquelin in 1798 (France). The name comes from from the mineral beryl, whose name comes from Greek beryllos.
What is beryllium used for?
Beryllium is used for: X-ray windows; aerospace and satellite structures; copper–beryllium spark-free tools; neutron reflectors in reactors.
Is beryllium a metal?
Yes. Beryllium is a alkaline earth metal, one of the metallic elements.
What is the electron configuration of beryllium?
The electron configuration of beryllium is [He] 2s2. Its 4 electrons are arranged in shells as 2, 2.