H20 Bond Angles
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H20 Bond Angles
In lecture, Dr. Lavelle discussed that H2O has bond angles of 107 instead of 109.5 due to the lone pairs. Without the lone pairs, wouldn't the bond angles be 180 since it would be linear without these lone pairs?
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Re: H20 Bond Angles
Hello,
When we have a lone pair of electrons present instead of bonding pairs, the bond angles decrease slightly, which is demonstrated in the H2O bond angles of 107 instead of 109.5. This is because we consider the electron repulsion. A lone pair and bonding pair repulsion is stronger than a bonding pair-bonding pair repulsion, thus the lone pair will push the bonds more, resulting in a bond angle that is slightly smaller than 109.5.
Hope this helps!
When we have a lone pair of electrons present instead of bonding pairs, the bond angles decrease slightly, which is demonstrated in the H2O bond angles of 107 instead of 109.5. This is because we consider the electron repulsion. A lone pair and bonding pair repulsion is stronger than a bonding pair-bonding pair repulsion, thus the lone pair will push the bonds more, resulting in a bond angle that is slightly smaller than 109.5.
Hope this helps!
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Re: H20 Bond Angles
Since the lone pairs are not placed on opposite sides of the central atom, electron repulsion will cause them to push the two bonded oxygens closer to each other.
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Re: H20 Bond Angles
Because water has two lone pairs surrounding the central oxygen atom, these will cause repulsion against the bonded hydrogen atoms. Because lone pair-lone pair repulsion is the strongest out of all, this will cause the hydrogen atoms to be pushed from the linear axial plane (electrons try to spread out as much as possible!) and become slightly bent
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Re: H20 Bond Angles
To answer your question, yes, without the lone pairs, the bond angles would be 180 degrees since it would be a linear shape with two regions of electron density. The two lone pairs in oxygen create repulsions that push the two hydrogens and affect their positioning, resulting in a bond angle slightly below 109.5. H20 has a bent molecular geometry.
Re: H20 Bond Angles
The lone pairs are responsible for the decreased bond angles, so therefore, without the lone pairs, the bond angles would be 180 degrees.
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Re: H20 Bond Angles
I think you misinterpreted what he meant when he said "due to the lone pairs". You are correct in thinking that without lone pairs, the shape would be linear and the angle would be 180. However, the 109.5 comes from the hypothetical situation where there were bonds in place of the lone pairs. Since there are lone pairs INSTEAD OF BONDS, the angle is 107 instead, due to the greater repulsive force from lone pairs than from bonds.
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Re: H20 Bond Angles
Because of the lone pairs on the oxygen, electron repulsion will cause the bond angle to be less than 120 degrees.
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