Polar Molecules

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

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Shreya Tamatam 3B
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Polar Molecules

Postby Shreya Tamatam 3B » Sat Dec 01, 2018 12:26 pm

How do you determine if a molecule is polar or non polar by just looking at its Lewis structure?

Nicolette_Canlian_2L
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Re: Polar Molecules

Postby Nicolette_Canlian_2L » Sat Dec 01, 2018 12:27 pm

You can check the number of lone pairs on the central atom and try to determine the shape of the molecule to find the overall dipole moment (if it exists).

Ariel Cheng 2I
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Joined: Fri Sep 28, 2018 12:29 am

Re: Polar Molecules

Postby Ariel Cheng 2I » Sat Dec 01, 2018 3:01 pm

It would be best to, from the Lewis structure, figure out the shape of the molecule through VSEPR and use the electronegativity of each atom to determine the total dipole movement.

Bruce Chen 2H
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Re: Polar Molecules

Postby Bruce Chen 2H » Sat Dec 01, 2018 3:16 pm

Polar molecules will have a net dipole moment as there is asymmetrical. Nonpolar molecules are mostly symmetrical and have no dipole moment at all as they cancel out.

cristinapadilla_1E
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Re: Polar Molecules

Postby cristinapadilla_1E » Sat Dec 01, 2018 3:25 pm

Although looking at a molecule simply to determine whether or not it is polar or nonpolar, it is more accurate to use VESPR theory in order to deduce whether it is or not forsure.

Faith Fredlund 1H
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Re: Polar Molecules

Postby Faith Fredlund 1H » Sat Dec 01, 2018 5:03 pm

Some times you can determine if a molecule is polar or not by its Lewis Structure; however the VSEPR model is the most accurate to help determine the polarity of a molecule. By looking at the shape and determining the arrangement of the atoms in the molecule, you can then tell if it is polar or not. Generally, asymmetric molecules, molecules with dipoles that do not cancel, and molecules with odd numbers of different atoms are polar. Symmetric molecules tend to not be polar.

Erin Kim 2G
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Re: Polar Molecules

Postby Erin Kim 2G » Sat Dec 01, 2018 5:04 pm

You check for the net dipole moment of the molecule. If the dipole moments cancel out because if the symmetric structure of the molecule, then it is non polar. If there is a net dipole moment, the molecule is polar.

Zubair Ahmed 1L
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Re: Polar Molecules

Postby Zubair Ahmed 1L » Sat Dec 01, 2018 5:15 pm

In order to determine if a molecule is polar or non-polar, you can draw out the lewis structure and identify the dipole moments of the given molecule. If the dipole moments cancel, the molecule is non-polar. If the dipole moments do not cancel, the molecule is polar.

Swetha Ampabathina1I
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Re: Polar Molecules

Postby Swetha Ampabathina1I » Sat Dec 01, 2018 5:19 pm

Normally, if the structure is symmetrical, it is safe to assume it's nonpolar. However, if there are lone pairs on the central atom or the Lewis structure is unsymmetrical, it is most likely polar.

chrisavalos-2L
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Re: Polar Molecules

Postby chrisavalos-2L » Sat Dec 01, 2018 5:26 pm

A way that you determine whether or not a molecule is polar from looking at the Lewis structure is determining the dipole moments (if there are any), and if it does have dipole moments that do not cancel out then the molecule is polar.

Alli Hinmon 3E
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Re: Polar Molecules

Postby Alli Hinmon 3E » Sat Dec 01, 2018 7:01 pm

The way that I mentally do this is in my head add up all the valence electrons, then divide by 8. If the total number of v-electrons is not a factor of 8, there must be Lone pairs. When ever you have 1 pair of lone pairs, the molecule will be polar. Be careful because some lone pairs can surround molecules and not change its shape. Ex: if there are 3 pairs of lone pairs on a linear molecule then it will still be linear, it may also still be polar (it depends).

Aili Ye 4L
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Joined: Fri Sep 28, 2018 12:16 am

Re: Polar Molecules

Postby Aili Ye 4L » Sun Dec 02, 2018 4:27 pm

The way I look at it is to envision the shape and look at its symmetry. Usually non-symmetric shapes with lone pairs are polar, and symmetric shapes without lone pairs or have lone pairs that cancel each other out (as in the example of a square planar molecule) are non-polar.

Fionna Shue 4L
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Re: Polar Molecules

Postby Fionna Shue 4L » Sun Dec 02, 2018 11:49 pm

If the lewis structure is symmetrical, then it is non-polar because the dipole moments cancel out. If the lewis structure is asymmetrical or there are lone pairs on the central atom, then it is polar


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