TYPES OF RESONANCE IN CHEMISTRY PLUS
TYPES OF RESONANCE IN CHEMISTRY FREE

And the way we do it is we try to pick the least electronegative atom that is not hydrogen

And then the next step is let's try to actually draw this structure. One more extra electron, one more extra valenceĮlectron than you would expect if these were just freeĪtoms that were neutral. This has a negative oneĬharge right over here. Now the next thing we have to keep in mind is this is an anion.

TYPES OF RESONANCE IN CHEMISTRY PLUS

Up the valence electrons, if these were free, neutral atoms, you would get five plus 18, But if you have three oxygens, you're going to have six times three. Oxygen has one, two, three, four, five, six valence electrons.

TYPES OF RESONANCE IN CHEMISTRY FREE

In that second shell, if it's a neutral, free nitrogen atom. Nitrogen has one, two, three,įour, five valence electrons in its outer shell, and

The first step is to just account for the valence electrons. All right, well we'veĭone this many times. See if you can draw that, the Lewis structure for a nitrate anion. Nitrogen and three oxygens, and it has a negative charge. We can draw the Lewis diagram for a nitrate anion. Or if we have to have formal charge, placing the negative ones on more electronegative atoms and positive ones on less electronegative atoms. Stable resonance structures features include having fulfilled octets and absent formal charges. The more stable resonance structures contribute more so to the resonance hybrid than do the less stable ones. The true structure is a combination of all the resonance structures which we refer to as the resonance hybrid.Ī second question arises, do the constituent resonance structures contribute equally to the resonance hybrid? The answer is, no, certain resonance hybrid contribute to the molecule’s structure to a greater degree than others. The question then becomes, which one of these resonance structures represents the true structure of the molecule? The answer is all of them do.

Instead there are multiple possible, valid structures which could exist which we call resonance structures.

So when we correctly identify the bond orders (single and double bonds) then these bonds are indeed covalent bonds as you stated where the electrons are being shared between the bonding atoms.Ĭertain molecules cannot be represented by a single Lewis structure. And remember the most important point is that it's not us creating these bonds, it's us trying to determine what type of bonding is actually occurring the molecule. So when we take that lone pair from oxygen, it's not really us taking oxygen's electrons since they never completely belonged to it in the first place. And before the double bond is formed each oxygen has 7 electrons and the nitrogen has only 3 electrons which means we've allocated some of the nitrogen's electrons to the oxygens already.īasically it's more correct to think about these valence electrons being more fluid and being able to move around the molecule more easily than being static and belonging to a single atom. Each oxygen brings six valence electrons as individual atoms and the nitrogen atom brings five electrons. If we think of each atom's electron belonging to it then even before we form the double there's some unequal distribution in a sense. Well Sal only put those lone pairs on each of the oxygen atoms in the first place to use up all the valence electrons according to the method used to create Lewis structures.

Types of resonance in chemistry