Is the Nitrogen in NH3 sp3 or sp2 + 2p ?

  • Thread starter Hammad Shahid
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In summary: Energy diagrams are a bit more useful but they still don’t capture everything.In summary, the boron will bond with the extra lone pair in NH3. This is only possible if we let Nitrogen stay unhybridized. However, the molecular structure for NH3 is tetrahedral (and is therefore hybridized as sp3) due to distancing the e- pairs. If we go by this model, however, NH3 has no lone pair to donate to the empty orbital of BF3.
  • #1
Hammad Shahid
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I want to draw out the product of the reaction between NH3 and BF3.
In the reaction between NH3 and BF3, the boron will bond with the extra lone pair in NH3. This is only possible if we let Nitrogen stay unhybridized. However, the molecular structure for NH3 is tetrahedral (and is therefore hybridized as sp3) due to distancing the e- pairs.
If we go by this model, however, NH3 has no lone pair to donate to the empty orbital of BF3.

Also, how is it that NH3 contains a lone pair but does not show that in energy diagram. From what I know, if an element has a lone pair, it will be an unhybridized orbital in the energy diagram.

Thanks for any help.
 
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  • #2
It’s a distorted SP3. The lone pair occupies a large volume and the barrier to inversion with respect to nitrogen is fairly low so it behaves a lot like an isolated p suborbital.
 
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chemisttree said:
It’s a distorted SP3. The lone pair occupies a large volume and the barrier to inversion with respect to nitrogen is fairly low so it behaves a lot like an isolated p suborbital.
Alright. So for the energy diagram, how would I draw this? Sp3 or Sp2 + 2p2 ?
 
  • #4
Draw it like an SP3. Energy diagrams are not extremely useful for visualizing structures though. You do realize that the energy of an unshared electron pair is different than bonded electrons? So that the energy diagram of ammonia will look different than something like methane even though both are SP3?



 
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  • #5
chemisttree said:
Draw it like an SP3. Energy diagrams are not extremely useful for visualizing structures though. You do realize that the energy of an unshared electron pair is different than bonded electrons? So that the energy diagram of ammonia will look different than something like methane even though both are SP3?




Yes I know that. That's why I'm confused on why the energy diagram would have it as an sp3 hybridization rather than show the lone pair separately.
 
  • #6
What are you calling an “Energy Diagram?” An MO diagram?

If you are referring to the MO diagram you must acknowledge that hybridization is used to explain what is wrong given a particular MO diagram interpretation. Without hybridization, carbon can only form two bonds rather than the four that we see in the real world. Likewise, a strict MO interpretation for ammonia gives us a localized electron pair in an s suborbital and three non-equivalent combinations of 1s and 2p suborbitals. This is not reality. The observed energies and bond angles don’t fit the MO handwaving description at all.
Something must be invoked to explain the H-N-H bond angles of 107 degrees (not 90!) and the observed dipole moment (not ~0!). So hybridization is invoked to explain these differences. Rather than a combination of atomic orbitals, a combination of hybridized atomic orbitals is used.

These diagrams are a bit like using a cartoon to explain real life. You get the gist of it but details are lacking. I will say it again... MO diagrams aren’t extremely useful for visualizing structures or predicting them.
 
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Related to Is the Nitrogen in NH3 sp3 or sp2 + 2p ?

1. What is the molecular structure of NH3?

The molecular structure of NH3 is trigonal pyramidal, with the nitrogen atom at the center and three hydrogen atoms bonded to it. This means that the nitrogen atom has a sp3 hybridization, with four electron domains surrounding it.

2. How is the nitrogen atom in NH3 hybridized?

The nitrogen atom in NH3 is sp3 hybridized, meaning that its four valence electrons are distributed among four hybrid orbitals. This hybridization allows for the formation of four covalent bonds, with three bonds to hydrogen atoms and one bond to the lone pair of electrons on nitrogen.

3. Is the nitrogen atom in NH3 sp2 or sp3 hybridized?

The nitrogen atom in NH3 is sp3 hybridized. This is because it has four electron domains, which requires four hybrid orbitals. The sp3 hybridization allows for the formation of four covalent bonds, resulting in the trigonal pyramidal molecular structure of NH3.

4. How many p orbitals are involved in the hybridization of nitrogen in NH3?

In the sp3 hybridization of nitrogen in NH3, there are four hybrid orbitals involved. Three of these orbitals are formed by the combination of one s orbital and three p orbitals, while the fourth orbital is formed by the combination of one s orbital and one p orbital. Therefore, there are four p orbitals involved in the hybridization of nitrogen in NH3.

5. What is the difference between sp2 and sp3 hybridization?

The main difference between sp2 and sp3 hybridization is the number of electron domains around the central atom. In sp2 hybridization, there are three electron domains and three hybrid orbitals, resulting in a trigonal planar molecular structure. In sp3 hybridization, there are four electron domains and four hybrid orbitals, resulting in a tetrahedral or trigonal pyramidal molecular structure. Additionally, sp2 hybridization involves the combination of one s orbital and two p orbitals, while sp3 hybridization involves the combination of one s orbital and three p orbitals.

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