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anonymous
 one year ago
How many resonance structures does NH3 have?
I believe that there are none, but I would like some confirmation...
anonymous
 one year ago
How many resonance structures does NH3 have? I believe that there are none, but I would like some confirmation...

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Photon336
 one year ago
Best ResponseYou've already chosen the best response.1Do you know what resonance is?

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0I think that a resonance structure is a visualization of molecular structures, a more comprehensive representation than the Lewis Structure.

Photon336
 one year ago
Best ResponseYou've already chosen the best response.1Good, another way to explain it is this; Resonance shows the movement of pi electrons, remember you can't have resonance in a molecule with only sigma bonds i'll show you these. look at this example, is there any resonance in this structure? dw:1440992251474:dw

Photon336
 one year ago
Best ResponseYou've already chosen the best response.1Now here is an example of a molecule with resonance

Photon336
 one year ago
Best ResponseYou've already chosen the best response.1for resonance, we can move the pi electrons around, if there is a place for them to go, i.e. a more electronegative element, or if they are in conjugation, after every other bond there's a double bond. The best example of this is let's say we have a carbocation, that's a carbon with a positive charge on it, and right next to it we have a double bond. we can move this double bond to the adjacent carbon, and we can get two structures. REMEMBER WE DID NOT BREAK ANY BONDS. we just moved pi electrons. dw:1440992586160:dw

Photon336
 one year ago
Best ResponseYou've already chosen the best response.1So let' me show you for NH3 let's draw it out. it's a trigonal pyramidal structure, with one lone pair. dw:1440992699341:dw You can clearly see that for NH3 we have 3 sigma bonds the NH single bonds and one lone pair. we don't have any double bonds, meaning there aren't any pi electrons in this molecule so we cant make a resonance structure.

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0So, just to recapitulate, it is only when we have pi bonds that we can make a resonance structure?

Photon336
 one year ago
Best ResponseYou've already chosen the best response.1@robinjane Yeah kind of, You know what a pi bond is right? did you learn about hybridization?

Photon336
 one year ago
Best ResponseYou've already chosen the best response.1FYI we use hybridization because the atomic orbitals don't reflect how the bonding of a molecule. for instance Carbon has 6 electrons. and atomic carbon would be. \[1s ^{2}2s ^{2}2p ^{2}\] Based on this model, atomic carbon only has 3 orbitals available to make a bond. we obviously know that this is does not reflect the bonding of molecular carbon because carbon makes 4 bonds. dw:1440993189911:dw

Photon336
 one year ago
Best ResponseYou've already chosen the best response.1So the scientists made up this other notion called a hybrid orbital that's between the energy of an a s and a p orbital, to give you an sp orbital now the bonding of carbon depends on how many orbitals we want to use. let's look at this structure: METHANE CH4 (Carbon makes four bonds) so we need four orbitals to do this. dw:1440993357848:dw We get four SP3 orbitals, hybridized. YOU NOTICE SOMETHING RIGHT? each orbital can hold a maximum of 2 electrons, and has one electron in each of the orbitals. this means that the other electro comes from none other than hydrogen. dw:1440993416313:dw Another representation dw:1440993548016:dw

Photon336
 one year ago
Best ResponseYou've already chosen the best response.1Now, my last post will try to explain to you the best I can where this notion of Pi bonds come from.

Photon336
 one year ago
Best ResponseYou've already chosen the best response.1dw:1440993683373:dw In this figure you notice something right? see that orbital that's above and below the plane? that's called a PI bond. Here's how it's formed For Ethene, we know that we need to make three bonds one to the carbon, and two to the other hydrogens. But WAIT. we have another orbital that's unhybridized a P orbital that sticks above and below the plane. that's called our pi bond. dw:1440993893494:dw We get the following: We have one P orbital that can participate in the pi bonding but the same thing happens for the adjacent carbon dw:1440993959866:dw So the two carbons in the center are both Sp2 hybridized. dw:1440993683373:dw Funny thing about pi bonds though. Because the are above and below the plane, we can move them around and such, resonance, and they can also serve as nucleophiles, IF you're in organic chemistry, the most important thing though is because they are above and below the plane and not between the two nuclei these can be moved around. The electrons in a sigma bond cant be moved around so easily, you dont know where an electron will be but there' a higher probability it will be between the two nuclei ( unrelated though).

Photon336
 one year ago
Best ResponseYou've already chosen the best response.1So in general pi bonds are important because we can move them around, and when you have more complex molecules, resonance is based off of this fact, that you can move these pi electrons around to give you a better picture of what's going on in a molecule. Just remember, that electrons aren't localized; there's a greater chance that they will be in certain places of the molecule than others' and that has to do with things like electornegativty. Also when drawing out multiple resonance structures a thing to keep in mind is that there's resonance structures too have hierarchies, some structures predominate more than others I believe. I suggest going to your textbook and looking for some examples, just to see what's going on but that;'s the heart of it movement of pi bonds. Hope this helps you and anyone reading this.

Photon336
 one year ago
Best ResponseYou've already chosen the best response.1Btw welcome to openstudy

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0Thank you so much! This was very helpful...my course is not very clear on a lot of concepts...:)

Photon336
 one year ago
Best ResponseYou've already chosen the best response.1Just take it one step at a time; try to look for some resonance problems online ; also there are rules to resonance too as to how to rank which resonance structure contributed more than the other
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