C4 Flashcards
Resonance theory
Can be applied to Lewis model or Ao model
Predicts localised bonding
Resonance theory
States that there can be various possible structures for a molecule and that no individual one is correct but all of them contribute to the true structure
What is a resonance arrow
Indicates 2 different forms of the same molecule
Double headed arrow
Curly arrow
Show the movement of a pair of electrons
Radical arrow
Show the movement of only a single electron
Arrow with only half an arrow head
Drawing resonance structures
Written by moving electrons
Only position of electrons move
Double headed arrow needed
What can be a source of electrons / nucleophile
Negative charge
Lone pair
Bond
The sink / acceptor of the electron / electrophile
Positive charge
Partial positive charge
Atom happy to accept electrons such as electronegative atom
O,N, halogen
Nucleophile
Source of electrons
Start of curly arrow
Maybe a lone pair
Negatively charged
Nucleophile
Source of electrons
Start of curly arrow
Maybe a lone pair
Negatively charged
Electrophile
Sink of electrons
Can be positively charged
Destination of a curly arrow
How much does each form of resonance contribute
Structures with more covalent bonds are more stable
Structures with charge separation are less stable
Structures where a negative charge is on an electronegative atom are more stable than those in electro positive atom
