Second Midterm (part 1) Flashcards
Are resonance structures two different molecules?
No. A molecule with resonance structures is actually a hybrid between all the resonance structure where nothing is changing
Resonance structures are denoted by a _____ _____ arrow.
double headed
Do resonance structures have equal weightings?
Sometimes yes, but not always
What is the purpose of curved arrows on a resonance structure?
They are to show how we got from one resonance structure to another
Is a resonance structure with charge separation and an incomplete possible?
yes
A resonance structure with charge separation is _____ favourable than one without
less
A bronsted acid is a _____ _____.
proton donor
A bronsted base is a _____ _____.
proton acceptor
What is the scale of pKa in water?
0-14
The scale of pKa be extend in ____ ____ using extrapolation from ____ to ____
organic solvents
-10 to 50
Strong acids have ____ pKa’s
low
Weak acids have ____ pKa’s
high
The conjugate base of a strong acid is a ____ ____
weak base
the conjugate base of a weak acid is a ____ ____
strong base
HCl is a ____ acid
strong acid
why is HCl a strong acid?
because it completely dissociates in water and it conjugate base Cl- is very stable in water
Equilibria will always lie toward the ____ (more ____) acid and base
weaker
stable
basicity decreases as you go to the ____ (same row) on the Periodic Table
right
More electronegative atoms can hold a negative charge ____ and thus _____ anions or lone pairs
better
stabilize
Larger atoms can hold a negative charge ____ since the charge is spread out in a much larger orbital.
better
Resonance structures make a molecule ____ stable because the charge is _____.
more
delocalized
More electronegative atoms can ____ a negative charge through one or more bonds via “induction”
stabilize
A Lewis acid ____ a lone pair
accepts
A Lewis base ____ a lone pair
donates
___ ____ denote the “motion” of a pair of electrons
Curved arrows
Curved arrows denote the ____ or ___ of a covalent bond in a reaction
making
breaking
Curved hours always start at a pair of electrons either a ____ ____ or ____ ____
lone pair
bonded pair
______ means electron loving
electrophile
Electrophiles are ____ ____
Lewis Acids
nucleophiles ____ a pair of
electrons to an electrophile to form a new covalent bond
donate
Nucleophiles are ____ ____
Lewis bases
What do S, N, and 2 stand for in SN2?
S = substitution N = nucleophilic 2 = bimolecular
The SN2 reaction is bimolecular because the rate of the reaction depends on both the concentration of the ____ and the concentration of the _____: thus, the reaction is said to obey second- order kinetics.
nucleophile
electrophile
In SN2 reactions, the electrophilic carbon is said to undergo ____ ____
Walden Inversion
The transition state in ___ reactions has no definable lifetime
SN2
The SN2 reaction is said to be _____ because the attack by the nucleophile and the departure of the leaving group occur in concert (simultaneously)
concerted
Are there any intermediates in an SN2 reaction?
No because the reaction occurs in concert