Boron (B)
Boron (B) is element 5 of the periodic table, a metalloid in period 2 and group 13. Its standard atomic weight is 10.81, so one mole of boron atoms has a mass of 10.81 g. At room temperature it is a solid; it melts at 2074.85 °C and boils at 3999.85 °C.
| Atomic number | 5 |
|---|---|
| Symbol | B |
| Standard atomic weight | 10.81 |
| Molar mass | 10.81 g/mol |
| Category | Metalloid |
| Group | 13 |
| Period | 2 |
| Block | p-block |
| Electron configuration | [He] 2s2 2p1 |
| Oxidation states | +3 |
| Electronegativity (Pauling) | 2.04 |
| Atomic radius (van der Waals) | 192 pm |
| First ionisation energy | 8.298 eV (800.6 kJ/mol) |
| Electron affinity | 0.277 eV |
| State at room temperature | Solid |
| Melting point | 2348 K (2074.85 °C) |
| Boiling point | 4273 K (3999.85 °C) |
| Density | 2.37 g/cm³ |
| Discovered | 1808 |
Group 13
Calculate with Boron
Atomic weight: IUPAC CIAAW standard atomic weight. Other properties: PubChem (U.S. National Library of Medicine, public domain). Values such as melting point and radius depend on how they were measured; check a data book for precise work.