#resonance structures

[er-cryptid]

[just-a-chem-studyblr]

Today's work: VSEPR, oxidation numbers and resonance structures

[nandlalgupta2009]

[organiclearning-blog]

Bond line structures are useful and easy to read, however they are somewhat inadequate due to the mobility of electrons. Because electrons have no fixed location within a molecule or compound they can be delocalized throughout the structure; however, some spaces are more likely to have a higher electron density than others.

As a result organic chemist generally look at something called resonance. Resonance structures are used when one (Lewis) Structure cannot fully explain the bonding that occurs between the atoms. 2+ high energy structures are considered a part of the resonance hybrid which shows the overall delocalization. The more resonance structures a molecule has, the more stable it is. It is important to note that resonance structures only change the position of the electron not the structure of the molecule.

Delocalization and Resonance Rules

Structures should have the same number of electrons and lone pairs (LP)- no more, no less.

Resonance structures must follow the rules of Lewis Structures

Hybridization must remain the same

Only the electrons move - do not rearrange bonds

Resonance Hybrids

When drawing Resonance structures, use solid lines for bonds

A dotted line can be used to show a double or triple bond present

Draw only the LP found in all resonance structures

Stability Rules

Greater number covalent bonds = Greater stability due to complete octets

Most stable structure has the least number of formal charges

Stable structures have the least separation of formal charge

Negative charges on the atom with the higher electronegativity is more stable and positive charges on atom with the higher electropositivity is more stable.

Equivalent resonance structure attribute equally to stability.

[libartsecology]

this was one of my favorite lectures so far 

[alegitdiamond]

Polar or Not?

I'm not polar because I have a negative charge all around. I also don't have any resonance structures because I only have single bonds. 

[okhemistr-blog]

Resonance Structures: Recognizing Patterns

1. A lone pair next to a pi bond.

2. A lone pair next to a positive charge

3.A pi bond net to a positive charge.

4.A pi bond between two atom. where one of those atoms is electronegative.

5. Pi bonds going all the way around a ring.

[okhemistr-blog]

Resonance: Step by Step

1. Can we convert any lone pairs into pi bonds?

2.Can we convert and pi bonds into lone pairs?

3.Can we convert pi bonds into pit bonds?

**Double and Triple bonds are pi bonds