Show all possible resonance structures for each of the following molecules or ions: (a) Nitrate

step 1 Okay, in this question, we are drawing resonant structures. So let's get started. Our first stru

Show all possible resonance structures for each of the...

Key Concepts

Electron Delocalization

Electron delocalization refers to the spreading out of electrons over several atoms rather than being confined between two atoms. This delocalization, which is depicted through resonance structures, contributes to the stability of the molecule or ion by lowering the overall energy of the system.

Formal Charge

Formal charge is a concept used to estimate the charge distribution within a molecule by comparing the number of valence electrons in an isolated atom to the number accounted for in the Lewis structure. Calculating formal charges helps in evaluating the stability of different resonance structures and ensuring that the overall charge of the molecule or ion is correct.

Lewis Structures

Lewis structures are diagrams that map out the valence electrons in a molecule, illustrating how atoms are bonded and where lone pairs reside. They provide the basic framework for understanding the distribution of electrons, which is essential when constructing and comparing resonance forms.

Resonance Structures

Resonance structures are different Lewis representations of the same molecule that show alternative ways in which electrons can be arranged without altering the positions of the atoms. They indicate that the actual electron distribution is a hybrid of these forms, allowing for a more accurate description of the molecule’s electronic structure.

Transcript

00:01 Okay, in this question, we are drawing resonant structures.

00:06 So let's get started.

00:08 Our first structure is n -o -3 -m minus.

00:16 And to draw the low -stnot structure, we calculate how many valence electrons we have.

00:21 So five from the nitrogen, six from each of the oxygens, and then one from the free electron from that negative charge.

00:30 And that is equal to 24.

00:36 And so if we draw out our lewis structure, let's say we have three bonds, two electrons per bond.

00:54 So we're going to subtract six electrons from our total.

00:57 That gives us 18 electrons to redistribute.

01:02 And that distributes nicely into six electrons per oxygen.

01:09 But if we look at this nice.

01:14 Nitrogen, this nitrogen only has access to six electrons.

01:20 Three bonds, two electrons each, no free pairs, that's six electrons.

01:24 Nitrogen's not happy.

01:26 So we're going to try moving two electrons from the oxygen as from free pairs into a bond.

01:38 So i'm going to volunteer these two electrons to form a bond.

01:44 And now it looks like we're in good shape because this nitrogen has four bonds.

01:48 Eight electrons, and this oxygen still has eight electrons, four free electrons, and then four from lebovans.

01:57 So this is a possible structure.

02:01 Now with resonant structures, we can reach the same distribution of electrons more or less, but with different oxygen atoms.

02:17 So in this case, the nitrogen is double bonded to the oxygen on the right hand side.

02:29 And there's not a big difference between these two in terms of stability because, well, if you calculate your formal charges, they're all going to be the same.

02:41 Likewise, we can draw one more configuration where the double bond is on the left hand oxygen.

02:58 And all of these structures have the same energetic favorability.

03:05 So you would expect a 33 % distribution for each of these individual resonant structures.

03:18 Okay.

03:20 Our next compound is nitric acid.

03:24 So we have h .n .o .3.

03:35 Okay, from the previous question, you know that the structure for the no3 is going to look something like this.

03:48 And with this h, we are going to just add a hydrogen to one of these oxygens.

04:00 And we are not going to forget to dot in our free electrons.

04:12 Okay.

04:13 So that is a possible little structure for this nitric acid.

04:18 And let's just do a quick sanity check to make sure we have all the right electrons.

04:24 So we know hydrogen has one electron, nitrogen brings five, and the three oxygens bring a total of 18.

04:32 So in total we would expect 24 electrons.

04:40 We have eight here.

04:41 We have eight here, and we have eight here.

04:47 Eight times three is 24.

04:49 Looks good.

04:51 And all of the atoms are satisfied the octet rule with the exception of hydrogen...

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