Atomic number 4
Beryllium
Alkaline earth metal
Quick facts
- Atomic mass
- 9.012
- Group
- 2
- Period
- 2
- State (STP)
- solid
- Electronegativity
- 1.57
- Common ox. states
- +2
Properties
Electron configuration
[He] 2s²
- Ionization energy
- 899.5 kJ/mol
- Electron affinity
- -48.0 kJ/mol
- Melting point
- 1560.00 K (1286.8 °C)
- Boiling point
- 2742.00 K (2468.8 °C)
How it bonds
Beryllium loses both 2s electrons to make Be²⁺, but it is small and highly polarizing — most beryllium compounds (BeCl₂, BeF₂) are essentially covalent rather than ionic. With only two valence electrons it often forms electron-deficient molecules (BeCl₂ in the gas phase is linear with two bonds and no lone pairs).
Where you meet it
- Periodic Quest challengeunlock card