Hybridization of orbitals for Phosphorus in Phosphate Ion

[Conservation]

A relatively easy question regarding hybridized orbital (keep getting confused for some reason):

What is the hybridization state for the central phosphorus atom in a phosphate ion? I would presume that it would be sp3d to fulfill the expended octet/five bonds with the four oxygen atoms, but I read from a different online source that it is in fact sp3.

And, for quick check, this would mean that there are 4 sigma bonds and 1 pi bonds, right?

Thanks.

 

[DrDu]

Your question is not relatively easy. Although this is still widely taught, d-orbitals are never relevant to set up hybrid orbitals in main group elements.
The actual hybridization in phosphorous compounds is not something given, but rather a question of your own preferences.
sp3 does not seem to be a bad choice.

Maybe you have access to the following article via your library:
http://www.sciencedirect.com/science/article/pii/S1380732399800223
or
http://pubs.rsc.org/en/content/articlelanding/1997/ft/a700708f/unauth#!divAbstract
which treats somewhat similar sulphur compounds.

 

[Conservation]

I don't understand-there are five bonds in the ion. How can it be sp3?

 

[DrDu]

I don't understand-there are five bonds in the ion.

First, what makes you so sure that there are 5 bonds?
Second, there are many ways to set up 5 bonds: The bonds are highly ionic, so you can set up plenty of resonance structures with several covalent and several ionic bonds.
You are even free to chose different hybridizations in different resonance structures.

 

[LudusRex]

I can confirm that the hybridization state for the central phosphorus atom in a phosphate ion is indeed sp3. This is because phosphorus has five valence electrons and needs to form five bonds in order to fulfill the octet rule. In sp3 hybridization, one s orbital and three p orbitals combine to form four sp3 hybrid orbitals, allowing for the formation of four sigma bonds with the four oxygen atoms. The remaining p orbital can then participate in a pi bond with one of the oxygen atoms, resulting in a total of five bonds. So, in summary, there are four sigma bonds and one pi bond in a phosphate ion.

I understand that it can be confusing to see different sources stating different hybridization states, but it is important to keep in mind that hybridization is a theoretical concept used to explain the observed bonding behavior of atoms. It is not always a clear-cut answer and can vary depending on the specific molecule or ion in question. However, in the case of a phosphate ion, the sp3 hybridization state is the most commonly accepted explanation. I hope this helps clarify any confusion.