Is CO Polar or Nonpolar?

Why is CO Polar?

Carbon monoxide has a triple bond between C and O. Oxygen (3.44) pulls electrons toward itself, but carbon also has a lone pair pointing away from oxygen that partially offsets this pull. The two effects nearly cancel, giving CO an unusually small dipole of only 0.11 D — with the negative end on carbon, not oxygen.

• Electronegativity difference: O (3.44) is significantly more electronegative than C (2.55), creating partial charges on each atom and making the individual bonds polar.
• Linear shape (—): The asymmetric molecular geometry means the bond dipoles point in directions that do not cancel — they add up to produce a net dipole moment of 0.11 D.
• Net dipole moment (0.11 D): Any molecule with a nonzero net dipole moment is classified as polar. The 0.11 D dipole moment of CO confirms its polar character.

Molecular Geometry of CO

CO has a linear molecular geometry with a bond angle of —. Here is why this shape determines polarity:

• The central atom's electron pairs arrange themselves to minimize repulsion, resulting in the linear shape.
• The — bond angle creates an asymmetric arrangement — the bond dipoles point in directions that do not perfectly oppose each other.
• Asymmetry is the key: if CO had a perfectly symmetric geometry, its bond dipoles would cancel and the molecule would be nonpolar. The linear shape prevents this cancellation.

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 CO:

• C (central atom) electronegativity: 2.55
• O (outer atom) electronegativity: 3.44
• Difference: 0.89 — above the ~0.5 threshold, so the C–O bonds are polar

The combination of polar bonds and an asymmetric linear geometry means the partial charges do not cancel — making CO a polar molecule with a net dipole of 0.11 D.

Is CO Polar or Nonpolar? (Quick Answer)

CO (Carbon Monoxide) is polar. CO is a weakly polar molecule — oxygen pulls electrons toward itself, but the lone pair on carbon partially offsets this, resulting in a very small dipole of 0.11 D.