Compound reference
Boron trifluoride
BF₃
The chemistry
Boron breaks the octet rule. Only three bonds, no lone pair, completely flat. F's electronegativity makes the molecule polar at each bond but the symmetry cancels.
Remember it as…
Three bonds, zero lone pairs, only 6 electrons on B. The empty seat above boron is what makes BF₃ a Lewis acid.
Common mix-up
Don't force a B=F double bond to satisfy the octet - fluorine never double-bonds in a stable molecule. Boron is genuinely electron-deficient (6 electrons) and that's why it's so eager to react.
Where the name comes from
Boron from Arabic buraq (borax, the mineral). The element was first isolated by reducing borax with potassium.
Where you meet it
Industrial catalyst; reacts vigorously with anything carrying a lone pair (NH₃, H₂O, ethers); a textbook example of "electron-deficient eager to react."
PubChem facts
- IUPAC name
- trifluoroborane
- Molecular weight
- 67.81 g/mol
Also known as: boron fluoride
Handling note
A corrosive, toxic gas that fumes in moist air; labs handle it in sealed, dry systems.
BondingMolecular geometry
Chemical data from PubChem (NIH/NCBI)