Chapter 2: Molecular Representations Flashcards
What is a functional group?
A functional group is a characteristic group of atoms/bonds that show a predictable chemical behavior. The chemistry of every organic compound is determined by the functional groups present in the compound.
What is resonance stabilization?
The delocalization of electrons via resonance.
What are the two rules for drawing curved arrows for resonance structures?
- Avoid breaking a single bond
- Never exceed an octet for second-row elements.
What are the five patterns to look for when drawing resonance structures?
- An allylic lone pair
- An allylic carbocation
- A lone pair adjacent to C+
- A pi bond between two atoms of differing electronegativity
- Conjugated pi bonds enclosed in a ring.
Relate octets to most significant resonance forms.
The most significant resonance forms have the greatest number of filled octets.
Relate formal charge to most significant resonance forms.
The structure with fewer formal charges is more significant.
Relate electronegative elements to most significant resonance forms.
Other things being equal, a structure with a negative charge on the more electronegative element will be more significant. Similarly, a positive charge will be more stable on the less electronegative element.
What are equivalent resonance forms?
Resonance forms that have equally good Lewis structures are described as equivalent and contribute equally to the resonance hybrid.
What is a resonance hybrid?
Resonance structures collectively represent only one entity–the resonance hybrid–which is a combination of the individual resonance structures.
What role do delocalized lone pairs play in resonance?
A delocalized lone pair participates in resonance and occupies a p orbital
What role do localized lone pairs play in resonance?
A localized lone pair does not participate in resonance. Whenever an atom possesses both a pi bond and a lone pair, they will not both participate in resonance.
