Periodic table / Alkaline earth metals
4Beryllium
Beryllium is an alkaline earth metal in group 2, period 2. At 25 °C it is a solid.
- Symbol
- Be
- Atomic number
- 4 protons in the nucleus
- Standard atomic weight
- 9.0122 ± 0.0001
- Electron configuration
- [He] 2s2
- Electrons in each shell
- 2, 2
- Group, period, block
- 2, 2, s
- Family
- Alkaline earth metals
- State at 25 °C
- solid
- Electronegativity
- 1.57 (Pauling scale)
- First ionisation energy
- 899.5 kJ/mol (9.322699 eV)
Where these numbers come from
Atomic weight: IUPAC CIAAW, abridged standard atomic weights 2024. Electron configuration and ionisation energy: NIST Atomic Spectra Database. Family, state and electronegativity: PubChem. See Sources. Melting points, boiling points and densities are left out for now: published values differ between sources, and we will add them once each has been checked.