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Is BCl3 Polar or Nonpolar?
Boron trichloride has a trigonal planar geometry with 120° bond angles and no lone pairs on boron. Each B–Cl bond is polar (Cl is more electronegative than B), but the three bonds are arranged symmetrically in a plane. Their dipoles point outward at equal angles and cancel completely, giving BCl3 a net dipole of 0 D.
Why is BCl3 Nonpolar?
Boron trichloride has a trigonal planar geometry with 120° bond angles and no lone pairs on boron. Each B–Cl bond is polar (Cl is more electronegative than B), but the three bonds are arranged symmetrically in a plane. Their dipoles point outward at equal angles and cancel completely, giving BCl3 a net dipole of 0 D.
- Symmetric trigonal planar geometry (120°): The atoms are arranged symmetrically around the central atom. This forces all bond dipoles to point in directions that cancel each other out exactly.
- Polar bonds that cancel: The electronegativity difference between Cl (3.16) and B (2.04) creates polar bonds — but the trigonal planar shape ensures their dipoles cancel perfectly.
- Zero net dipole (0 D): Because all bond dipoles cancel, the net dipole moment is 0 D. Any molecule with zero net dipole moment is classified as nonpolar.
Molecular Geometry of BCl3
BCl3 has a trigonal planar molecular geometry with a bond angle of 120°. Here is why this shape determines polarity:
- The trigonal planar arrangement places all outer atoms at equal angles (120°) from the central atom, creating perfect spatial symmetry.
- Each bond dipole has an equal and opposite counterpart — they cancel in pairs, leaving no net charge separation.
- Symmetry is the key: even if the individual bonds are polar, the trigonal planar geometry ensures a net dipole of 0 D.
Electronegativity and Polarity
Electronegativity measures how strongly an atom attracts bonding electrons. A difference greater than ~0.5 on the Pauling scale generally means the bond is polar.
In BCl3:
- B (central atom) electronegativity: 2.04
- Cl (outer atom) electronegativity: 3.16
- Difference: 1.12 — above the ~0.5 threshold, so the B–Cl bonds are polar
Even though the individual bonds are polar (difference = 1.12), the trigonal planar geometry of BCl3 causes them to cancel completely. Polarity depends on both bond polarity AND molecular shape.
Is BCl3 Polar or Nonpolar? (Quick Answer)
BCl3 (Boron Trichloride) is nonpolar. BCl3 is a nonpolar molecule because its trigonal planar symmetry causes the three polar B–Cl bond dipoles to cancel each other completely.
Frequently Asked Questions
Is BCl3 polar or nonpolar?
BCl3 is a nonpolar molecule because its trigonal planar symmetry causes the three polar B–Cl bond dipoles to cancel each other completely.
Why is Boron Trichloride nonpolar?
Boron trichloride has a trigonal planar geometry with 120° bond angles and no lone pairs on boron. Each B–Cl bond is polar (Cl is more electronegative than B), but the three bonds are arranged symmetrically in a plane. Their dipoles point outward at equal angles and cancel completely, giving BCl3 a net dipole of 0 D.
What is the shape of BCl3?
BCl3 has a trigonal planar molecular geometry with a bond angle of 120°. This shape causes all bond dipoles to cancel perfectly, giving a net dipole of 0 D and making the molecule nonpolar.
Does BCl3 have a dipole moment?
No. BCl3 has a dipole moment of 0 D. Its trigonal planar geometry causes all individual bond dipoles to cancel out completely, resulting in a nonpolar molecule.