Polarity

[Emilie_Paltrinieri_1K]

Is a molecule that has a lone pair polar?

[Ashley Ko 3I]

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!

[Jayasree Peri 2J]

I agree with Ashley! The reason having a lone pair might make a molecule polar is because the lone pair distorts the symmetry of the molecule and basically pushes the bonded atoms into a different formation.

[Jiapeng Han 1C]

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.

[Lauren Sarigumba 1K]

A molecule is considered polar when there is a difference in electronegativities between the atoms and when the polar bonds are NOT equally distributed in the space.

[Armen_Isayan_2L]

A molecule that has a lone pair is not necessarily always polar, most of the time it is, however, the arrangement of the molecule, if it is symmetrical, plays a significant role in determining its polarity.

[Minh Nguyen 3H]

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.

[Mina Tadros 3L]

Lone pairs do not automatically make a molecule polar. Only if the lone pairs are located in one particular section of the molecule (thus, they're not canceling each other) will the molecule be polar.

[Zach Richardson 2f]

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.

[Jaden Ji 2K]

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.

[Jaden Ji 2K]

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.
viewtopic.php?t=845#:~:text=Answer%3A%20It%20is%20often%20true,s)%20and%20not%20be%20polar.

[Gian Boco 2G]

You can't know simply from that. You would need the other bonded atoms as well as the shape of the molecule in order to see if the dipole moments remain or cancel out.

[Anthony_Sandoval_1D]

Lone pair does not mean a molecule is automatically polar. As others have said above, if an atom is symmetrical the usually this plays a bigger role in its polarity.

[Jeffrey Fenn 1G]

Not always, I would look at this section in the textbook, that is what really helped me.

[Alex Benson]

I believe that if there is only one lone pair that makes the molecule polar, and it can be non polar if there are multiple lone pairs that balance each other out.

[Rebecca Preusch 2C]

Only if the molecule has polar bonds and the lone pair makes it asymmetrical

[Reece Fong 2k]

A molecule that has a lone pair on the central atom is polar, but not if it has a lone pair on the bonded atoms. A general rule of thumb is that a molecule is polar if it a) has a lone pair on the central atom or b) has different bonded atoms that don't cancel out