How to Draw Resonance Contributors
Most arrows in chemistry cannot be used interchangeably, and care must be taken to select the correct arrow for the job. Electrons have no fixed position in atoms but have probabilities of being found in certain spaces (orbitals), and resonance forms depict areas of higher probabilities (electron densities).
The electrons in resonance structures can move to help stabilize the molecule, and all resonance structures must follow the rules for writing Lewis Structures. The most ideal resonance structure has the fewest formal charges that add up to zero or the overall molecule’s charge.
Step 1: Make a drawing of the Lewis Structure.
Liza Chu (UCD) and Sharon Wei (UCD)
What are the rules for drawing resonance structures?
The hybridization of the structure must remain the same, the skeleton of the structure cannot be changed (only the electrons move), and resonance structures must have the same number of lone pairs.
What are three exceptions to the octet rule?
Molecules with an odd number of electrons, such as NO; molecules in which one or more atoms possess more than eight electrons, such as SFsub>6/sub>; and molecules in which one or more atoms possess less than eight electrons, such as BClsub>3/sub>, are the three general exceptions to the octet rule.
Is SO3 a resonance?
Answer: (SO3)2- has three resonance structures, one for each structure formed when sulfur bonds with oxygen in a double bond.
Does 03 have a resonance structure?
Ozone, or O3, has two major resonance structures that both contribute equally to the overall hybrid structure of the molecule, accounting for the required 18 valence electrons (six from three bonds and twelve from lone pairs on the oxygen atoms).
What makes a resonance structure more stable?
The resonance structures with complete valence shells, which means most atoms have a full octet, are more stable, as are the structures with a negative charge on the more electronegative atom. The difference between the two resonance structures is the placement of a negative charge.
What is equivalent resonance?
Any two or more stages between the complete displacement of a charge over an unsaturated alkyl group or between an alkyl and a non-alkyl group are known as equivalent resonance structures.
Are all aromatic compounds resonance?
Aromatic compounds are unsaturated hydrocarbon ring structures with unique properties, such as unusual stability, due to their aromaticity; they are often represented as resonance structures with single and double bonds.
Can resonance break octet rule?
Because structure E has 12 valence electrons and structure F has 14 valence electrons, the rule is broken above, and E and F are not resonance structures (F also violates the octet rule).
Does acetone have resonance structures?
Importantly, placing less than a full octet on nitrogen or oxygen, as in the acetone example (above right), is a bad idea because these atoms are highly electronegative, making these resonance forms extremely unstable and meaningless.
Which is the major resonance structure?
The most stable structures contribute the most to the resonance hybrid, and they are called major resonance contributors. We can often write more than one Lewis structure for a molecule, differing only in the positions of the electrons.