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Water is asymmetrical? What?


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LMAO. Sorry you are probably a first year. Google VSEPR (Valence Shell Electron Pair Repulsion theory) and sp3 hybridization.

 

In a nut shell, the e- orbitals in the central O are arranged in the shape of a tetrahedron with two points/orbitals involved in bonds with H and two points occuppied by lone e- pairs. Because O is highly electronegative the H have partial positive charges and the O has partial negative charge. If the molecule was linear like CO2 then the partial charges would cancel out but because it is bent there is a net dipole moment.:cool:

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No no, I'm in my final year of high school, I was merely quickly glancing through my High school "Biology 12" textbook.

 

WaterSymmetry.jpg

 

So I guess the electrons are taken into consideration when determining whether a molecule is symmetric or asymmetric, and not just the atoms.

 

Wow, I have a lot to learn.

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The text means asymmetrical in the sense that the molecule is bent due to the trigonal planar configuration of the bonding and nonbonding electrons:

 

http://www.hrw.com/science/si-science/chemistry/atomic_structure/molecules/img/02h20.gif

 

Careful here. Water is not trigonal planar. When you consider the lone pairs, water is actually tetrahedral, when they are not considered, water is bent. An example of a molecule that is trigonal planar is BF3 (boron trifluoride). However, the part about the asymmetry described is correct.

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Careful here. Water is not trigonal planar. When you consider the lone pairs, water is actually tetrahedral, when they are not considered, water is bent. An example of a molecule that is trigonal planar is BF3 (boron trifluoride). However, the part about the asymmetry described is correct.

 

Yep, I just meant the shape that the filled orbitals take. Didn't mean to imply that water is trigonal planar under VSEPR theory.

 

No no, I'm in my final year of high school, I was merely quickly glancing through my High school "Biology 12" textbook.

 

WaterSymmetry.jpg

 

So I guess the electrons are taken into consideration when determining whether a molecule is symmetric or asymmetric, and not just the atoms.

 

Wow, I have a lot to learn.

 

You should've been taught VSEPR theory in SCH4U if you're a student in Ontario.

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Yep, I just meant the shape that the filled orbitals take. Didn't mean to imply that water is trigonal planar under VSEPR theory.

 

Oh okay..but don't the filled orbitals still take the bent/angular shape...someone correct me if I am wrong.

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Oh okay..but don't the filled orbitals still take the bent/angular shape...someone correct me if I am wrong.

 

Ah sorry, I think I see where I confused you. The filled orbitals actually take a tetrahedral shape. (Forgot the second unbonded pair). Silly me.

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No no, I'm in my final year of high school, I was merely quickly glancing through my High school "Biology 12" textbook.

 

WaterSymmetry.jpg

 

So I guess the electrons are taken into consideration when determining whether a molecule is symmetric or asymmetric, and not just the atoms.

 

Wow, I have a lot to learn.

 

Again, axis. The molecule IS symmetrical in the plane illustrated in that axis. Just draw the line VERTICALLY through the oxygen and you'll (hopefully) understand what the text was getting at.

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You might care to think of this way, don't try to get too technical. Think about the properties of your atoms... so :

 

Oxygen is very electronegative. The electrons in its bond with Hydrogen will be more shifted towards the oxygen most of the time, than towards the hydrogen. Additionally, it has lone pairs, that are going to love hanging out around the oxygen. For this reason, you see a lot of negativity around the oxygen, and less negativity around the hydrogen atoms.

 

So, now, yes the atoms are symmetrical... but what's the deciding factor? Well, the lone pairs are floating around the oxygen and this gives it a BIT more negativity resulting in your polarity.

 

I hope that made sense.

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Indeed, so it is not feasible to take only the atoms into consideration when determining molecular symmetry. The electrons, bonded or not, play a pivotal role in molecular symmetry.

 

Yeah they do, and with good reason. The electrons are negatively charged. That means they are going to be adding to the polarity of the molecule (by providing addtional negativity to a certain area).

 

Hope that helps a bit. :)

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"Water's polar covalent bonds and asymmetrical structure create a highly polar molecule"

 

The oxygen end of the bent water molecule has a partial negative charge while the hydrogens have a partial positive charge. In a charge sense, water is asymmetrical because one end is slightly negative while the other ends are slightly positive. This asymmetry in charges makes it a highly polar molecule.

 

You were thinking about symmetry in the shape sense. Yes, if you took a water molecule and chopped the bent shape in two you would get two symmetrical pieces.

 

Hope that helps.

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"Water's polar covalent bonds and asymmetrical structure create a highly polar molecule"

 

The oxygen end of the bent water molecule have a partial negative charge while the hydrogens have a partial positive charge. In a charge sense, water is asymmetrical because one end is slightly negative while the other ends are slightly positive. This asymmetry in charges makes it a highly polar molecule.

 

You were thinking about symmetry in the shape sense. Yes, if you took a water molecule and chopped the bent shape in two you would get two symmetrical pieces.

 

Hope that helps.

 

Good explanation...I think all of us were focusing on the shape instead of charge density.

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