Beryllium (Be)
Beryllium (Be) is element 4, an alkaline earth metal. Atomic mass 9.0121831, configuration [He] 2s². Properties, isotopes, oxidation states, uses and history, with an interactive 3D atom model.
Key facts
| Atomic number | 4 |
|---|---|
| Symbol | Be |
| Standard atomic weight | 9.0121831(5) |
| Category | Alkaline Earth Metal |
| Group | 2 |
| Period | 2 |
| State at room temperature | Solid |
| Electron configuration | [He] 2s² |
| Valence electrons | 2 |
| Common oxidation states | +2 |
| Common ions | No common ions |
| Electronegativity (Pauling) | 1.57 |
| First ionization energy | 900 kJ/mol |
| Atomic radius | 112 pm |
| Density | 1.85 g/cm³ |
| Melting point | 1283°C |
| Boiling point | 2471°C |
| Specific heat | 1.825 J/(g·°C) |
Natural isotopes
- Be-9: Stable
Common uses
- X-ray windows
- Non-sparking tools (alloys)
Where it matters
- Aerospace engineering (James Webb Telescope mirrors)
- Nuclear physics (Neutron reflector)
Hazards
- Highly toxic (Berylliosis)
- Carcinogenic
History
| Discovered | 1798 |
|---|---|
| Discovered by | Louis-Nicolas Vauquelin |
| Name | Friedrich Wöhler |