Non-polar atoms with lone pairs

(Polar molecules, Non-polar molecules, etc.)

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EvaLi_3J
Posts: 53
Joined: Wed Oct 02, 2019 12:16 am

Non-polar atoms with lone pairs

Postby EvaLi_3J » Sun Nov 24, 2019 12:18 pm

If a molecule has 1 lone pair, is it ever gonna be non-polar?
If it has 2 lone-pairs, can it be non-polar, since the lone pairs could possibly cancel each other?
If it has 3, 4, 5..., can it still be non-polar?

Kate Osborne 1H
Posts: 102
Joined: Fri Aug 30, 2019 12:16 am

Re: Non-polar atoms with lone pairs

Postby Kate Osborne 1H » Sun Nov 24, 2019 12:21 pm

Atoms with lone pairs can be non-polar, for example I2.

Sharon Rodriguez 3H
Posts: 50
Joined: Wed Nov 14, 2018 12:18 am

Re: Non-polar atoms with lone pairs

Postby Sharon Rodriguez 3H » Sun Nov 24, 2019 2:33 pm

The majority of the time it is true that if a molecule has lone pairs, it will be polar. There are cases, like stated above, where molecules have lone pairs but are nonpolar. Remember to keep in mind the molecular geometry and dipole moments when considering this, there will always be exceptions so there is no straight answer but I hope this helps!

TheresaDsilva4A
Posts: 53
Joined: Thu Jul 25, 2019 12:17 am

Re: Non-polar atoms with lone pairs

Postby TheresaDsilva4A » Sun Nov 24, 2019 2:36 pm

I have a follow-up question: How can we tell that dipole moment vectors cancel when they are at angles to one another (e.g. in a molecule with trigonal planar geometry)? Do we have to break up the vectors into their individual components?

Amanda Mei 1B
Posts: 109
Joined: Sat Aug 24, 2019 12:16 am

Re: Non-polar atoms with lone pairs

Postby Amanda Mei 1B » Sun Nov 24, 2019 7:22 pm

TheresaDsilva4A wrote:I have a follow-up question: How can we tell that dipole moment vectors cancel when they are at angles to one another (e.g. in a molecule with trigonal planar geometry)? Do we have to break up the vectors into their individual components?


If all the bonds are between the same 2 atoms, they cancel out if the molecular is symmetrically arranged - no side has a more negative or positive charge than another. However, if there is a bond between the same central atom but a different atom, the difference in electronegativities will most likely be different, resulting in different dipole moments. Sometimes you'll need to consider the geometric shape of the molecule to determine if the the bonds are symmetrically arranged or not.


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