What Shape Does BF3 Have?

BF3 has a Trigonal planar molecular geometry (AX3, trigonal planar) with a bond angle of 120°. The central boron carries 3 bonding domain(s) and 0 lone pair(s) — 3 electron domains in total. Three equivalent bonding domains and no lone pair give perfect planar symmetry.

Hybridisation is conventionally described as sp2. Polarity: Nonpolar: the three equal B–F dipoles lie in one plane and cancel.

1. Molecular Identity and Key Parameters

Molar mass is the average value rounded for procurement use. Hybridisation labels are the conventional VSEPR-level description; orbital treatment becomes more nuanced at higher levels of theory.

2. Drawing the Lewis Structure of BF3, Step by Step

1. Count valence electrons: 3 (B) + 3×7 (F) = 24 — a total of 24 electrons (12 pairs) must be placed.
2. Build the skeleton: place the boron at the centre and attach the terminal atoms with single bonds; hydrogen is never a central atom. Each single bond consumes 2 electrons.
3. Complete terminal octets: distribute the remaining electrons as lone pairs on the terminal atoms first (hydrogens already carry their duet from the single bond).
4. Satisfy the central atom: Three B–F single bonds around boron (six electrons on B); each fluorine keeps three lone pairs.
5. Check formal charges and resonance: All formal charges are zero in the neutral planar form.
6. Verify: Boron is content at six electrons; π donation from the fluorines partially offsets the empty orbital, which is exactly what makes BF3 a strong Lewis acid. Apply the standard formal-charge check (valence − nonbonding − half of bonding electrons) to confirm the drawn form.

A worked diagram of this molecule is kept in the companion guide: BF3 Lewis structure.

3. VSEPR Analysis: Why BF3 Is trigonal planar

VSEPR theory counts electron domains — every σ bond counts once regardless of bond order, and every lone pair counts once. BF3 has 3 such domains around the boron: 3 bonding and 0 lone. 3 domains correspond to a trigonal planar electron-domain arrangement; with no lone pair to hide the observed molecular shape is trigonal planar (AX3).

Bond angle: 120° because three equivalent bonding domains and no lone pair give perfect planar symmetry.

Polarity: Nonpolar: the three equal B–F dipoles lie in one plane and cancel.

4. The Most Common Mistake When Drawing BF3

5. Why the Geometry Matters in Practice

Supplied as BF3·Et2O or BF3·MeOH complexes for Friedel–Crafts acylations, polymerisation catalysis and fluoroborate synthesis.

Structure-level identity is exactly what a purchase order has to fix: the same molecular formula can hide isomers, hydrates or salt forms with different handling profiles. Before ordering, match CAS (7637-07-2), assay, water content and container rating against the datasheet, and request the COA batch that will ship.

Compare Boron Trifluoride (BF3) supply offers →

6. Quick FAQs on BF3

7. References

1. IUPAC / Gillespie, Assessment of the VSEPR model. Basis of AXE notation and lone-pair ordering. VSEPR entry
2. PubChem compound record for Boron Trifluoride (BF3). Registry number, formula and computed descriptors. PubChem 7637-07-2
3. Companion Lewis-structure guide on this site. Worked diagram for BF3. Lewis structure BF3