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Hi! If a molecule has lone pairs, this does not always mean it is polar. For instance, a molecule with lone pairs is only polar if the lone pairs cause the atoms surrounding the central atom to become asymmetrically arranged. As a result, the dipole moments would not cancel out. However, if you are referring to molecules that have 1 lone pair, I believe most of these molecules would be polar (molecular shapes with one lone pair tend to be polar). Hope this helps!
Not necessarily so, however, lone pair could indeed disrupt the symmetry of a molecule. For a molecule with lone pairs to be non-polar, the lone pairs must cancel out. For example, consider XeF4 where the lone pairs are opposite each other(one on top and one on bottom) and the covalent bonds form a square-planar shape.
A molecule with a lone pair does not mean that the molecule is polar. For one, the lone pairs have to be on the central atom. Assuming this is true, than the lone pairs have to impact the shape of the molecule in such a way that it becomes asymmetrical, in which case the overall molecule would be polar.
Forgive me if I am wrong, but I cannot think of an example with one lone pair that is not polar. I think that if the lone pairs are opposite each other they will cancel out. If I am wrong I would appreciate it if someone corrected me.
A lone pair does not make a molecule polar, but usually if an atom is asymmetrical then it is polar because the dipole moments cancel each other out. On a nonpolar molecule, the dipole moments cancel each other out, which makes all the molecule neutral overall.
Zach Richardson 2f wrote:Forgive me if I am wrong, but I cannot think of an example with one lone pair that is not polar. I think that if the lone pairs are opposite each other they will cancel out. If I am wrong I would appreciate it if someone corrected me.
Actually that's really interesting! I found this old forum that gives an example of how multiple lone pairs can cancel each other out, but I don't see an example proving it wrong. But I think you're right.
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