Consider the following bond lengths: C-O 143 pm C=O 123 pm C≡O 109 pm In the

Consider the following bond lengths: C-O 143 pm ...

Key Concepts

Bond Order and Delocalization

Bond order refers to the number of chemical bonds between a pair of atoms, and in molecules with delocalized electrons, the effective bond order is the average of the contributing structures. In the carbonate ion, the electron delocalization distributes a partial double bond character to each C-O bond, resulting in bond lengths that are intermediate between typical single and double bonds.

Resonance

Resonance is the concept that a single molecular structure can be represented by two or more contributing structures which differ only in the placement of electrons. In the carbonate ion, resonance illustrates that the double bond character is delocalized across all three C-O bonds, leading to equivalence among them.

Transcript

00:01 So in this question, consider the following bond length of carbon single bond oxygen that is 143 picometer.

00:10 Then carbon double bond oxygen is 123 picometer and carbon triple bond oxygen is 109 picometer.

00:24 So but in carbonate ion, you can see that in carbonate ion which is equal to co3, 2 minus iron, all three, all three co bonds have identical bond lengths.

00:52 That is 136 picometer, 136 picometer.

01:02 Find out the reason why in case of carbonate ion all co bond length have identical bond length which is 136 picometer so first we can see that the in case of carbonate iron the total number of valence electron in carbon is 4 and oxygen is 6 into 3 that mean 18 and we can add 2 electrons for the 2 minus so which means 24 electrons in the in the resonance structure of a carbon so we can see that the lewis diagram for carbonate ion that is co3 2 minus iron so this is carbon and this is double bond oxygen this is oxygen and this is oxygen and here we can use electrons so here one two three four five six six six electrons and here one two three four five six so this is negative charge and this is again negative charge and here one two three four electrons so this is a louis diagram for this carbonate ion so we can see that in the carbonate ion according to the louis diagram has two type of carbon oxygen bond so that when we can see that one double bond and two single bond two single bond so it's suggest that one carbon oxygen bond in the carbonate ion is shorter and stronger than each of the other two.

02:44 But we can see that experimentally, however, the carbon oxygen bond in the carbonate ion have same identical length.

02:59 But experimentally, experimentally, the three carbon oxygen bonds in the carbon carbon, carbonate ion have identical or have this same bond length, same bond length.

03:33 So that is 136 picometer.

03:37 So that means 136 picometer.

03:41 So we can see that the lewis diagram fails to explain the structure and bonding in the carbonate iron.

03:48 So we can see that the two additional lewis diagram.

03:51 So two additional lewis diagrams, lewis diagram can be drawn for this carbonate ion, can be drawn for this carbonate co3 to minus ion.

04:19 So we can see that.

04:21 So this is our carbon and we can make here double bond oxygen and then, here single bond oxygen then here single bond oxygen now we can use electrons so 1 2 3 4 5 6 and here 1 2 3 4 5 6 so when we count total electron 2 4 6 8 10 12 14 16 18 18 20 22 24 so that mean 24 electrons involved so now we can see that the formal charge so so we can see that the formal charge in case of this carbonate ion, in case of structure, we can say it is structure number one...

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