ElementsWhat is beryllium?
Beryllium is a light, stiff, steel-grey metal. Its dust is harmful to the lungs, so it is handled with care in industry.
What is beryllium used for?
Windows for X-ray tubes, parts for satellites and space telescopes, and copper alloys for springs and tools that do not make sparks.
Where the name comes from
From beryl, the mineral it was first found in. Emerald and aquamarine are forms of beryl.
Key facts
- Symbol
- Be
- Atomic number
- 4
- Atomic mass
- 9.012183 u
- Family
- Alkaline earth metal
- Period
- 2
- Group
- 2
- Block
- s
- State at room temperature
- Solid
- Melting point
- 1,287 °C (1,560 K, 2,348 °F)
- Boiling point
- 2,471 °C (2,744 K, 4,480 °F)
- Density
- 1.85 g/cm³
- Electrons per shell
- 2, 2
- Electron configuration
- [He]2s2
- Common oxidation states
- +2
- Electronegativity (Pauling)
- 1.57
- First ionisation energy
- 9.323 eV
- Electron affinity
- no value
- Atomic radius (van der Waals)
- 153 pm
- Discovered
- 1798
Place in the periodic table
Beryllium is element number 4. It sits in period 2 (row 2) of the periodic table, in group 2 (column 2), and belongs to the s-block. Just before it comes lithium (3), and just after it comes boron (5). In the same column, magnesium is below it. Elements in one column tend to behave alike.
Family: Alkaline earth metals.
Physical properties
At room temperature beryllium is a solid. It melts at 1,287 °C and boils at 2,471 °C, so it stays liquid over a range of 1,184 degrees. Its density is 1.85 grams per cubic centimetre, so a one-litre block would weigh about 1.85 kilograms. By density it ranks 78th among the 96 elements with a measured value.
Inside the atom
An atom of beryllium has 4 protons in its nucleus and, when neutral, 4 electrons around it. The electrons are arranged in 2 shells: 2, 2. The outermost shell holds 2 electrons. Written in full, the electron configuration is [He]2s2.
Its electronegativity on the Pauling scale is 1.57. This number shows how strongly an atom pulls shared electrons towards itself: fluorine, the strongest, is 3.98. Removing one electron from an atom takes 9.323 electronvolts (about 900 kilojoules per mole). One mole of beryllium weighs 9.012183 grams, so a single gram contains about 6.68 × 1022 atoms.
The ring picture is a simple model that only counts the electrons in each shell. Real atoms do not look like this.
Next steps
- Work out the weight of a compound that contains beryllium with the molar mass calculator.
- Compare it with every other element in the sortable list.
- Test yourself with the symbol quiz.
Figures on this page are from PubChem (U.S. National Library of Medicine), as downloaded on 11 November 2026. See About and data sources.