Exam 2 Flashcards
Brønsted-Lowry Acid
A compound that can donate a proton
Bronsted-Lowry Base
A compound that can accept a proton
Lewis Acid
any species that can accept electrons
Lewis Base
any species that can donate electrons
Ionic Bond
a bond between two atoms differing in electronegativity by > 2
Polar-Covalent Bond
a bond between two atoms differing in electronegativity by 0.5 - 2
Covalent Bond
a bond between two atoms differing in electronegativity by < 0.5
Enthalpy
the energy involved when bonds break or are formed
Bond Breaking is…
endothermic, +
Bond Forming is….
exothermic, -
Low pKa’s
Strong acid and weak conjugate base
High pKa’s
Weak acid and strong conjugate base
Bond Strength Effect
acidity increases as you go DOWN a group in the periodic table
Electronegativity Effect
acidity increases as you go from left to right across the periodic table
Effective Electronegativity of Carbons
Sp > Sp2 > Sp3
Sp = more acidic
Sp3= less acidic
Resonance Stabilization
the more resonances structures = stronger acid
Induction
long range electron pull in a molecule caused by the presence of electronegative atoms or electron withdrawing groups.
Helps to delocalize charge in a molecule, although it’s not nearly as good at delocalization as is resonance!
Where should the arrow point for acid-base reactions
it should always goes towards the weaker acid
Undecane
11
Dodecane
12
Tridecane
13
Tetradecane
14
Pentadecane
15
Hexadecane
16
Heptadecane
17
Octadecane
18
Nonadecane
19
Eicosane
20
What’s IUPAC stand for?
International Union of Pure and Applied Chemistry
What’s Dihedral Angle?
distance between reference subs
Lower NRG more or less stable?
more (Staggered)
higher NRG more or less stable?
less (eclipsed)
Torsional Strain
strain from bond-pair/bond-pair repulsion
True or False
substitutions can affect torsional strain?
true
What increases torsional strain?
- size increase (steric effect)
- increase of number of substituents
What’s more stable Gauche or Anti?
Anti
Fully eclipsed
2 largest constituents are on top of each other
Anti Staggered
2 largest constituents are far apart as they possible could be
Gauche Staggered
2 largest constituents closest to each other
What does combustion always produce?
H2O and CO2
Number of carbons (molecular weight) increases what?
heat combustion
The greater the amount of energy released = …….
the less stable
true or false
different conformations of molecules have different stabilities
true
Angle Strain
deviation of the C-C bond angles from ideal
What the major component of ring strain?
angle strain
What makes up ring strain?
angle strain + torsional strain
Puckered
4 carbons
Envelope
5 carbons
Half-Chair
multiple sets of eclipsing H’s
Boat
Flagpole interaction
Twist-Boat
Reduce Flagpole interaction
Rank least to most stable…
-chair
- boat
- half chair
-twisted boat
Stable - Chair
twist boat
boat
least - half chair
