Chemical element · Atomic number 5
Boron
Boron in the periodic table: atomic number 5, electron configuration, atomic mass, physical data, oxidation states, media credit and visible sources.
Metalloid
solid
10.81 u
A locally stored, license-verified sample photograph has not been curated yet.
Atomic classification
Shell occupancy
Boron in the Bohr shell model
This shows the electron distribution of the neutral atom in a simplified shell model.
- K · n=1
- 2 electrons
- L · n=2
- 3 electrons
- Electron configuration
- [He]2s2 2p1
- Electrons per shell
- 2 · 3
- Group
- 13
- Period
- 2
- Block
- P
- Element category
- Metalloid
Go from looking up chemistry to remembering it.
Turn your notes into source-backed study cards and review them at the right time.
Starter stays free · no payment details
Physical and chemical properties
- Atomic mass
- 10.81 u
- Standard state
- solid
- Density
- 2.37 g/cm³
- Melting point
- 2,348 K
- Boiling point
- 4,273 K
- Electronegativity
- 2.04 (Pauling)
- First ionisation energy
- 8.298 eV
- Oxidation states
- +3
- Discovery
- 1808
Safety and periodic classification
Safety
Safe handling cannot be inferred from Boron's position in the periodic table alone. Laboratory, classroom and disposal decisions must follow the documentation for the exact material and its safety data sheet.
Position and comparison
Boron is in period 2, group 13 and the P block. Its direct neighbours by atomic number are Beryllium and Carbon. The recorded Pauling electronegativity is 2.04. Periodic trends are compared only through the separately sourced neighbouring values.
Sources and scope
PubChem attributes element data to sources including IUPAC, NIST and IAEA. Quanta stores the referenced snapshot locally and leaves unknown values unavailable.