- Atomic Radius (Å)
Boron is a metalloid chemical element with symbol B and atomic number 5. Produced entirely by cosmic ray spallation and supernovae and not by stellar nucleosynthesis, it is a low-abundance element in both the Solar system and the Earth's crust. Boron is concentrated on Earth by the water-solubility of its more common naturally occurring compounds, the borate minerals.
5 Atomic Number
10.81 u Atomic Mass
2573.15 K Melting Point
4200 K Boiling Point
2.08 g/cm³ Density
1.2 Å Atomic Radius
0.84 Å Covalent Radius
2.04 Electronegativity
8.3 eV First Ionization Energy
26.99 Electron Affinity
2 Number of Shells
3 Electron Valency
2, 3 Electron Shell Occupations
1.03 J/g Specific Heat