MOLECULAR POLARITYFIELD NOTE 10 / 175
Is BCl3 polar or nonpolar?
BCl3 is nonpolar: its three polar B–Cl bonds are equivalent and lie 120° apart in a trigonal plane, so their dipoles cancel.
Boron Trichloride · trigonal planar
The molecule in space
Drag to turn the molecule. Show angles to read the model geometry.
01 / MODEL RECORDNIST geometry. Atom sizes and bond thickness are illustrative.How model data is used ↗
Lewis structure of BCl3
A Lewis diagram counts valence electrons. The model above shows the shape in space.
- 01
Bonds
Each B–Cl bond is polar, with electron density drawn toward chlorine.
- 02
Shape
Boron has three bonding regions and no lone pairs, so the three bonds form a trigonal plane.
- 03
Net dipole
The three equal bond dipoles cancel by symmetry; BCl₃ is nonpolar.
Why BCl3 is nonpolar
Boron has three bonding regions and no lone pair in the usual Lewis structure. Chlorine attracts each B–Cl bonding pair more strongly than boron, making every bond polar. NIST's D3h structure puts all three bonds in one plane at 120°, and the three dipole vectors sum to zero. Boron's incomplete octet does not override that molecular symmetry.
What to notice
Do not infer molecular polarity from one polar B–Cl bond. Three equal dipoles 120° apart cancel in planar BCl3; compare pyramidal, polar NH3.
Common questions about BCl3
- 01
What does the Lewis structure of BCl3 show?
B is joined to three Cl atoms by single bonds. Each Cl has three lone pairs, while B has six electrons around it rather than a full octet.
- 02
What is the molecular geometry of BCl3?
BCl3 has a trigonal planar molecular geometry. The 3D model shows representative bond angles of 120°. These angles come from the displayed model coordinates.
- 03
What is the molar mass of BCl3?
BCl3 has an approximate molar mass of 117.16 g/mol, calculated from its formula using abridged standard atomic weights. Natural isotope variation can change the last digits.