How much negative charge is on each oxygen of the carbonate ion?

oxygen-carbonate
bond-ion

#1

Consider the resonance structures for the carbonate ion.

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Concepts and reason
Carbonate ion acts as a base and it can form three resonance structures. If a compound has more number of resonance structures then it is more stable.

Fundamentals
Negative charge on each oxygen atom can be calculated by dividing the charge present oxygen atoms with number of oxygen atoms.

Calculate the bond order of each C-O bond by using the following expression.
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Part a
The resonance structures of carbonate ion are,

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Explanation:
Divide the charge present oxygen atoms with number of oxygen atoms to find out the charge on each oxygen atom.

Part b
The resonance structures of carbonate ion are,


Total number of bonds present in the carbonate ion is four.
Number of C-O (i.e. single bonds) bonds in carbonate ion is three.
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Explanation:
Total number of bonds present in the carbonate ion is four and number of C-O single bonds in carbonate ion is three. Divide the total number of bonds with number of C-O bonds to find out the bond order.