Vsper

[PrinceAli2786]

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Can someone explain to me the difference between regular molecular shape and electronic structure? How do you know which is which? And how do you decide/figure it out?

ex.

Bond angles for PF3:
First count the valence e- in total = 26. Divide using the VSEPR rules and you will find the central P has 3 bonding and one lone pair, making this molecule trigonal pyramidal (angle <109 degrees). Electronic structure is tetrahedral.


*Also random question:

Is Hemoglobin an enzyme? Prob. not, but what is it? Same w/ myoglobin what exactly ARE they? I know what they do, but what ARE they?

Thanks

 

[sleepy425]

Can someone explain to me the difference between regular molecular shape and electronic structure? How do you know which is which? And how do you decide/figure it out?

ex.

Bond angles for PF3:
First count the valence e- in total = 26. Divide using the VSEPR rules and you will find the central P has 3 bonding and one lone pair, making this molecule trigonal pyramidal (angle <109 degrees). Electronic structure is tetrahedral.


*Also random question:

Is Hemoglobin an enzyme? Prob. not, but what is it? Same w/ myoglobin what exactly ARE they? I know what they do, but what ARE they?

Thanks

All that's saying is that the molecule is trigonal pyramidal because if you were to draw just the bonds, it would be trigonal pyramidal. If you draw the bonds plus the lone pair it's tetrahedral. Honestly, i think the distinction is stupid because physically it's the same thing, it's all tetrahedral, it's just that in molecules like PF3 or NH3, you have a lone pair instead of one of the bonds to the ligands.

So basically, molecular shape takes into account just the orientation of the atoms and the bonds between them. Electronic structure takes into account the position of the atoms and the bonds between them, as well as the position of the lone pair, treating it as if it were just another bond to another atom.

As for hemoglobin and myoglobin, they're not enzymes. They're binding proteins. That's all, nothing fancy, just binding proteins. This is a common type of protein.

 

[PrinceAli2786]

All that's saying is that the molecule is trigonal pyramidal because if you were to draw just the bonds, it would be trigonal pyramidal. If you draw the bonds plus the lone pair it's tetrahedral. Honestly, i think the distinction is stupid because physically it's the same thing, it's all tetrahedral, it's just that in molecules like PF3 or NH3, you have a lone pair instead of one of the bonds to the ligands.

So basically, molecular shape takes into account just the orientation of the atoms and the bonds between them. Electronic structure takes into account the position of the atoms and the bonds between them, as well as the position of the lone pair, treating it as if it were just another bond to another atom.

As for hemoglobin and myoglobin, they're not enzymes. They're binding proteins. That's all, nothing fancy, just binding proteins. This is a common type of protein.

thank you very much for the response. Just one question, I pulled that out from YAHOO Answers, but wouldn't it be

PF3: Trigonal Planar for the molecular
and Trigonal Pyramidal for the electronic structure?

 

[sleepy425]

thank you very much for the response. Just one question, I pulled that out from YAHOO Answers, but wouldn't it be

PF3: Trigonal Planar for the molecular
and Trigonal Pyramidal for the electronic structure?

nah, it's trigonal pyramidal for the molecular, tetrahedral for electronic structure. PF3 has one lone pair and three F ligands. if it didn't have the lone pair both molecular and electronic would be trigonal planar. having the lone pair pushes the three ligands down into a trigonal pyramidal structure (for the molecular structure) and then tetrahedral for electronic structure. just think about it this way. draw the three ligands and then try to put the electron pair in. to put three ligands as far apart as possible, you put them in the same plane. when you try to add the extra lone pair, you have to keep everything as far apart as possible, so that would be tetrahedral. i think i said that twice but oh well.

lemme know if you have any questions about this...