Boron (B)
Boron is the 5th element, a metalloid in the p-block. Its standard atomic weight is 10.812.
Boron
10.812
What the table records
- Atomic number
- 5
- Standard atomic weight
- 10.812
- Group
- 13
- Period
- 2
- Block
- p-block
- Category
- Metalloid
- [He] 2s2 2p1
- Valence electrons
- 3
- Typical valence
- 3
- Van der Waals radius
- 1.8 Å
- Covalent radius
- 0.84 Å
Molecules containing boron
The lightest named structures in this library that contain B.
Boron
B · 10.81 g/mol
Borane
H₃B · 13.84 g/mol
Borohydride
H₄B- · 14.84 g/mol
sodium boranuide
H₄BNa · 37.83 g/mol
Cyano-borohydride
CH₃BN- · 39.85 g/mol
Boronic Acid
H₃BO₂ · 45.83 g/mol
Boron difluoride
BF₂ · 48.81 g/mol
Borate
BO₃-3 · 58.81 g/mol
Hydrogenborate
HBO₃-2 · 59.82 g/mol
Methylboronic Acid
CH₅BO₂ · 59.86 g/mol
Fluoro(dioxido)borane
BFO₂-2 · 61.81 g/mol
Boric Acid
H₃BO₃ · 61.83 g/mol
How to read these numbers
The standard atomic weight is an average over the isotopes as they occur naturally, which is why it is rarely a whole number. It is the figure a molar mass calculation uses. Work in mass spectrometry wants the monoisotopic mass of a single isotope instead, which is a different number.
The two radii are not the same measurement. The covalent radius is half the distance between two bonded atoms of the element; the van der Waals radius is how close a non-bonded atom gets before repulsion takes over, and is always the larger. Space-filling models are drawn with the second, ball-and-stick models with the first — which is why the same molecule looks so different in the two.