Boron (B)
Boron (B) is element 5, a metalloid. Atomic mass 10.81, configuration [He] 2s² 2p¹. Properties, isotopes, oxidation states, uses and history, with an interactive 3D atom model.
Key facts
| Atomic number | 5 |
|---|---|
| Symbol | B |
| Standard atomic weight | [10.806,10.821] |
| Category | Metalloid |
| Group | 13 |
| Period | 2 |
| State at room temperature | Solid |
| Electron configuration | [He] 2s² 2p¹ |
| Valence electrons | 3 |
| Common oxidation states | +3 |
| Common ions | No common ions |
| Electronegativity (Pauling) | 2.04 |
| First ionization energy | 801 kJ/mol |
| Electron affinity | 26.99 kJ/mol |
| Atomic radius | 87 pm |
| Density | 2.34 g/cm³ |
| Melting point | 2092°C |
| Boiling point | 4000°C |
| Specific heat | 1.026 J/(g·°C) |
Natural isotopes
- B-10: Stable (19.9%)
- B-11: Stable (80.1%)
Common uses
- Pyrex glass (Borosilicate)
- Fiberglass
- Detergents
Where it matters
- Agriculture (Essential plant nutrient)
- Nuclear safety (Control rods)
Hazards
- Low toxicity as element
- some compounds toxic
History
| Discovered | 1808 |
|---|---|
| Discovered by | Gay-Lussac & Thénard (and Davy) |
| Name | Derived from "Borax" |