Element 5
Boron (B)
Boron (B) is element 5 of the periodic table, a metalloid in period 2, group 13 (p-block) with an atomic mass of 10.81 and is a solid at standard conditions.
At a glance
- Atomic number
- 5
- Symbol
- B
- Atomic mass
- 10.81 u
- Category
- Metalloids
- Period
- 2
- Group
- 13
- Block
- p-block
- Phase at STP
- solid
Electron structure
- Electron configuration
- 1s2 2s2 2p1
- Shorthand configuration
- [He] 2s2 2p1
- Electrons per shell
- 2, 3
- Oxidation states
- +3
Physical properties
- Melting point
- 2,349 K (2,075.85 °C)
- Boiling point
- 4,200 K (3,926.85 °C)
- Density
- 2.34 g/cm³
- Phase
- solid
Atomic properties
- Electronegativity (Pauling)
- 2.04
- Atomic radius
- 87 pm
- Covalent radius
- 84 pm
- Van der Waals radius
- 192 pm
- First ionization energy
- 801 kJ/mol
- Electron affinity
- 27 kJ/mol
Notable isotopes
| Isotope | Mass | Abundance | Stability |
|---|---|---|---|
| B-11 | 11.00931 | 80.1% | Stable |
Common uses
- Fiberglass
- Ceramics
- Detergents
- Semiconductors
Discovery
- Year
- 1808
- Discovered by
- Joseph Louis Gay-Lussac, Louis Jacques Thénard
- Country
- France
Frequently asked questions
- Is boron a metal?
- Boron is a metalloid, which means it shows properties of both metals and nonmetals.
- How many protons does boron have?
- Boron has 5 protons. Its atomic number is 5, which is also the number of electrons in a neutral atom of boron.
- What group and period is boron in?
- Boron is in group 13 and period 2 of the periodic table, in the p-block.
- What is the atomic mass of boron?
- The atomic mass of boron is 10.81 u (unified atomic mass units).
Keep exploring
Boron's row is on the printable element property sheet, and its tile is on the periodic table wall chart - the same numbers as above, laid out for A4 or A3 paper.