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How many resonance structures can be drawn for #"PO"_4^(3-)#?

Answer 1

You can draw five resonance structures for #"PO"_4^(3-)#, but one of them is a minor contributor to the resonance hybrid.

If you start by drawing four oxygen atoms single bonded to a phosphorus atom and give every atom an octet, you get Structure R in the diagram below.

This is not a "good" structure , because it has five atoms with formal charges.

We can reduce the number of charges by moving electrons to convert a #"P-O"# single bond to a #"P=O"# double bond.

There are four #"P-O"# bonds, so we can draw four structures: S, T, U, and V.

These are all equivalent and are the major contributors to the resonance hybrid.

Hence, the actual structure is a resonance hybrid of all five structures, with : S, T, U, and V being the major contributor and R a minor contributor.

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Answer 2

Ryan Andrews

For the phosphate ion (( \text{PO}_4^{3-} )), there are three resonance structures that can be drawn.

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Answer from HIX Tutor

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.