acids and bases Flashcards
What is a Bronsted Lowry acid?
a proton donor
what is a bronsted base?
a proton acceptor
what does a bronsted acid become when it donates it’s proton?
a conjugate base
what does a bronsted lowry base become when it accepts the proton from the acid?
a conjugate acid
what is a lewis acid?
an electron pair acceptor
what is a lewis base?
an electron pair donor
what are electrophiles?
they are lewis acids that “love electrons” and they accept electrons
what are nucelophiles
they are lewis bases that are “nucleus lovers” and they donate electrons (Love positive charges)
what is acid strength dependent on?
the stability of its conjugate base
in general, what makes a conjugate base more stable?
if it’s negative charge is more stable
this is determined by:
- delocalization of negative charge
- electronegativity
- hybridization
- atomic size
how does electronegativity factor in conjugate base stabilization?
if the negative charge is on a more electronegative atom, it is more stable
what does size have to do with acidity?
An atom with a larger size will be have a more stable conjugate base since the charge can delocalize over a larger surface area
If an atom is larger than one that is more electronegative, what does that say about its stability?
Size trumps electronegativity, the acid with the larger atom will have a more stable conjugate base than an acid with a smaller atom even if the electronegativity is higher
What does hybridization have to do with stability of conjugate bases?
anions that reside in orbitals with more s character are more stable than those with more p character since they are closer to the nucleus
electrons are more stable when they are close to the nucleus
which orbitals have the most s character
sp>sp2>sp3
what is the effect of electronegativity groupings on a conjugate base?
they delocalize the charge over the spread of the molecule
what is the resonance effect on an acid?
Acids with conjugate bases that have resonance are more acidic since the base can be stabilized by the delocalization of the charge on the base
the lower the pka, the :
stronger the acid
what order do the rules of stability go in?
atom, resonance, induction, orbital
IR spectroscopy is representative of what?
bond vibrations between atoms
what is the frequency of IR dependent on?
the mass of the atoms
the bond strength
the dipole moment changes
how does the mass of atoms affect IR spec?
heavy atoms have lower frequencies
how does bond strength affect IR spec?
stronger bonds have faster vibrations (Alkynes vs Alkanes)
what affect do dipole moments have on charges
the changes are detected in peaks, the dipole moment must change as vibration occurs
if an atom is symmetric (ethene)
there is no peak and it is known as IR inactive
what is the bond stretch of C=C
1650
What is the bond stretch of C=O
1700
what is the bond stretch an an alkyne (triple bond)
2100
what is the bond stretch of C-H
2900
what i sthe bond stretch of O-H
3500
What are substitution reactions?
The substrate (what is being reacted) is replaced by another molecule, causing the substrate to become a leaving group
What are Addition reactions?
Two molecules come together to form a larger one
What are elimination reactions?
A large molecule breaks into smaller molecules
what are rearrangements
reactions that form constitutional isomers of eachother, nothing comes in or out
electrons always flow from
electron rich to electron poor
what does a fishhook arrow curve represent
movement of one electron
what is a homolytic bond cleavage
1 electron goes to each atom in the bond
what is a heterolytic bond cleavage
one atom takes all the electrons while the other takes none
lewis acids are
electrophilic
lewis bases are
nucleophilic ( positive charge seeking)
what side does equilibirum favor?
the side with the weaker acid (larger pka)
what’s the difference between stereoisomers and constitutional
stereoisomers have the same molecular formulas and the same connectivities but DIFFERENT spatial arrangements
constitutional isomers have the same molecular formulas but different connectivities
