Polar/ Nonpolar

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Shana Patel 1C
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Polar/ Nonpolar

Postby Shana Patel 1C » Sat Nov 21, 2020 9:28 pm

Can shape alone tell if a molecule is polar or nonpolar?

Halle Villalobos 3E
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Re: Polar/ Nonpolar

Postby Halle Villalobos 3E » Sat Nov 21, 2020 9:32 pm

Hi! The answer is yes. A molecule is non-polar if the charge distribution is symmetric and polar if the charge distribution is asymmetric. After drawing your VSEPR model, you can analyze the molecule. If it has symmetry around the central atom, the bond dipole moments will "cancel out" and the molecule will therefore be non-polar. If the molecule is asymmetric, the bond dipole moments won't "cancel out" and the molecule will have a net dipole moment and the molecule is therefore polar. I hope this help!

Sana Nagori 2H
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Re: Polar/ Nonpolar

Postby Sana Nagori 2H » Sat Nov 21, 2020 9:55 pm

Yes but it still needs to have dipole moments. Molecules with only H-C bonds will never have a significant difference in electronegativity so no matter the shape they will never be polar.

Lillian Ma 1I
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Re: Polar/ Nonpolar

Postby Lillian Ma 1I » Sun Nov 22, 2020 3:16 am

Adding on to what people said earlier, if a shape is symmetrical, like tetrahedral or linear, the molecule is non-polar, unless one or more of the atoms in the molecules is different. If the atoms are not of the same element, then there is a preferential interaction which would make the molecule polar.

Chesca Legaspi 2E
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Re: Polar/ Nonpolar

Postby Chesca Legaspi 2E » Sun Nov 22, 2020 3:22 am

An easy trick that I use to tell if a molecule is polar or not is that if a molecule has different terminal atoms or a lone pair around the central atom, it'll be polar for sure!

Joanne Yuh 3I
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Re: Polar/ Nonpolar

Postby Joanne Yuh 3I » Sun Nov 22, 2020 3:23 am

I agree with what the people said above. I might be wrong but I think you can also use electronegativity calculations to calculate bond polarity to determine whether the overall molecule is polar or nonpolar.

Chenning Yang Dis3l
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Re: Polar/ Nonpolar

Postby Chenning Yang Dis3l » Sun Nov 22, 2020 4:33 am

It might be also okay to use electronegativity calculation to determine if polar or nonpolar.

Hailey Qasawadish 2J
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Re: Polar/ Nonpolar

Postby Hailey Qasawadish 2J » Sun Nov 22, 2020 10:38 am

One general rule that I’ve learned is that if a molecule has lone pairs on the central atom, it’s polar!

SamayaJoshi1A
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Re: Polar/ Nonpolar

Postby SamayaJoshi1A » Sun Nov 22, 2020 10:40 am

It might just be easier memorizing popular non-polar molecules. The ones with no lone pairs are almost always non-polar. The linear ones, one with three and four branches and no lone pairs are non-polar. There is a really helpful graph if you just look up "VSPER chart".

Will Skinner
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Re: Polar/ Nonpolar

Postby Will Skinner » Sun Nov 22, 2020 10:43 am

Shape is an indicator of polarity, but the molecule must also have dipole moments. It is important to consider both.

Tobie Jessup 2E
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Re: Polar/ Nonpolar

Postby Tobie Jessup 2E » Sun Nov 22, 2020 12:01 pm

Its been easiest for me to compare the electronegatvities of the atoms to determine in the molecule is polar, but shape is also an indicator as to whether or not an atom is polar.

Juliana Rosales 1H
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Re: Polar/ Nonpolar

Postby Juliana Rosales 1H » Sun Nov 22, 2020 1:38 pm

If you can tell based off of shape that is a very good way to figure it out, but it is always good to check with a other method if you can. I would say that It would be good for a quick guess, but you always want to be absolutely sure on some problems.

Tae Pasawat 2A
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Re: Polar/ Nonpolar

Postby Tae Pasawat 2A » Sun Nov 22, 2020 8:43 pm

No the shape alone cannot tell whether the molecule is polar or non polar. You must also look at the geometry of the molecule. If the geometry is not symmetrical but it has non polar bonds, then the molecule remains non polar. If the molecule is symmetrical and has polar bonds, the dipole moments are cancelled.

I would also like to add that a lone pair placed in the correct position can also cancel some of the dipole moments created by electronegative elements that create a partially negative charge!

Hailey Kang 2K
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Re: Polar/ Nonpolar

Postby Hailey Kang 2K » Sun Nov 22, 2020 8:49 pm

Hi!

You can use shape as a good indicator as to whether a molecule is polar or nonpolar. I would say that you still need to check whether or not the dipole moments cancel, but shape is a good check as well.

Joshua Chung 2D
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Re: Polar/ Nonpolar

Postby Joshua Chung 2D » Sun Nov 22, 2020 8:59 pm

Shape can be used to determine if a molecule is polar or nonpolar, but you must consider whether or not it has existing dipole moments. If dipole moments are not present or if they cancel each other out (with respect to shape), then it is nonpolar. If they exist and do not cancel out, then it is polar.

Arnav Saud 2C
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Re: Polar/ Nonpolar

Postby Arnav Saud 2C » Sun Nov 22, 2020 9:11 pm

Shape is a good indicator of whether or not something is polar/nonpolar; however, you also need to check the dipole moments as well.

105618850
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Re: Polar/ Nonpolar

Postby 105618850 » Sun Nov 22, 2020 10:05 pm

Yes, molecular shape often displays polarity. Differences in dipole moments result in an asymmetrical structure/unequal bond lengths.

James Patanian 2C
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Re: Polar/ Nonpolar

Postby James Patanian 2C » Sun Nov 22, 2020 10:06 pm

105618850 wrote:Yes, molecular shape often displays polarity. Differences in dipole moments result in an asymmetrical structure/unequal bond lengths.


With how frequently bond lengths can change, is it fair to say bond lengths that we know of are not ever really concrete measures but more so rough estimates?

Jack Kettering 3D
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Re: Polar/ Nonpolar

Postby Jack Kettering 3D » Sun Nov 22, 2020 10:08 pm

I find that shape is the easiest way to tell whether or not a molecule is polar or not so the answer to your question is yes!

FionaHunter21
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Re: Polar/ Nonpolar

Postby FionaHunter21 » Mon Nov 23, 2020 12:50 pm

Are there dipole moments between all atoms with a difference in electronegativity or just the polar bonds?

Ria Nawathe 1C
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Re: Polar/ Nonpolar

Postby Ria Nawathe 1C » Mon Nov 23, 2020 12:54 pm

FionaHunter21 wrote:Are there dipole moments between all atoms with a difference in electronegativity or just the polar bonds?

I believe all bonded atoms with a difference in electronegativity exhibit a dipole, but the magnitude/strength of the dipole is given by mu = |q|*d (charge * distance between the atoms).

Mohamed Mido
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Re: Polar/ Nonpolar

Postby Mohamed Mido » Mon Nov 23, 2020 12:57 pm

yes

Scot Widjaja Dis 1J
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Re: Polar/ Nonpolar

Postby Scot Widjaja Dis 1J » Sun Nov 29, 2020 11:38 pm

Yes they can. If you look at the molecules shape and see that all the bond dipoles get cancelled, then you know the molecule is no polar just by observing the structure.

Ke Huang 2G
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Re: Polar/ Nonpolar

Postby Ke Huang 2G » Sun Nov 29, 2020 11:38 pm

Yes, to see if the molecules are polar/ nonpolar, you need to know about the shape.


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