5 B Boron 10.81
Metalloid
Boron 硼
[He] 2s² 2p¹
- Period 2
- Group 13
- Block p
- Solid
Electron configuration
1s² 2s² 2p¹
Orbital diagram (valence)
2s ↑↓
2p ↑
- Electrons per shell
- 2, 3
- Unpaired electrons
- 1
- Zeff (Slater)
- 2.60
Properties
- Atomic weight
- 10.81
- Electronegativity (Pauling)
- 2.04
- First ionization energy
- 800.6 kJ/mol
- Electron affinity
- 26.73 kJ/mol
- Covalent radius
- 84 pm
- van der Waals radius
- 192 pm
- Melting point
- 2348 K
- Boiling point
- 4273 K
- Density
- 2.37 g/cm³
- Melting / boiling point
- 2074.8 °C / 3999.8 °C
- Common oxidation states
- +3
- Discovered
- 1808
Natural isotopes
| Mass number A | Atomic mass / u | Abundance |
|---|---|---|
| 10B | 10.012937 | 19.90 % |
| 11B | 11.009305 | 80.10 % |
Isotope masses: AME2020; abundances: IUPAC/CIAAW representative values.
Successive ionization energies
The big jumps appear where core electrons start to be removed. Ionization energies from the NIST Atomic Spectra Database.
Boron in the course
The lessons that discuss this element most (ranked by mentions).
- Boron, aluminium, carbon, silicon and the inert pair The main-group elements
- Boranes and clusters: counting skeletal electrons The main-group elements
- Lewis structures and formal charge Chemical bonds
- Kjeldahl nitrogen: from nitrogen to protein Titrimetric and gravimetric analysis
- The f-block and beyond Transition metals
- Extracting metals Transition metals
- Molecular polarity Molecular shape
- Symmetry and point groups Molecular shape
Periodic trend
Group 13
Data: PubChem periodic table (public domain); atomic weights are IUPAC abridged standard values; covalent radii from Cordero et al. (2008).