Chemical Bonding, Water, Acid-Base Balance (1-2) Flashcards
6 atoms in covalent bonds
C, H, O, N, P, S
valence
of bonds, determines what structures form
electronegativity
tendency to attract electrons, determines how molecules interact with each other
geometry
bond angle, determines shape of molecules
covalent bond
a pair of electrons shared by 2 atoms
double bond
2 atoms share 2 pairs of electrons
delocalization
sharing of electrons, lowers energy
lower energy =
greater stability, bond strength
valence of H
1
valence of C
4
valence of O
2
valence of N
3
valence of S
2
valence of P
5
rank electronegativity
O>N>S=C>H=P
more electronegative atoms attract
electrons more strongly
less electronegative atoms attract
electrons less strongly
covalent bonds can be
polar or nonpolar
ions do not form
covalent bonds
ions form
electrostatic bonds with oppositely charged molecules
tetrahedral shape
CH4, NH3-, H2O
double bonds structure
flat planar structure
single bonds rotate
freely around single bonds
double bonds rotate
they do no rotate
which atoms have nonbonded electron pairs
O, N, S
N in NH3 has a tendency to
capture H+
O atom of a water molecule can accept both electrons from an OH bond and
release the hydrogen
acid is a H+
donor
base is an H+
acceptor
electron resonance
sharing of electrons by 3 or more atoms
what is the most stable structure of phosphoric acid
PO4H-2
most of the enrgy yielded by ATP hydrolysis comes from
additional resonance stabilization of ADP
Carbon-oxygen groups
alcohol, aldehyde, ketone, carboxylic acid, ether, acid anhydride
carbon-sulfur groups
sulfhydryl group, disulfide
carbon-nitrogen groups
amino group, quaternary amine
which groups are made up in a pyruvic acid
carboxyl, keto, methyl
pyruvic acid modifications
decarboxylation, carboxylation, amino transfer, reduction
non-covalent bonds
hydrogen bonds, electrostatic bonds, hydrophobic bonds, Van der Waals forces
hydrogen bonds
attractive force between H atom in polar covalent bond and unpaired electrons of electronegative atoms
strength of H bonds is dependent on
distance and orientation
electrostatic bonds
attractive forces between + and - charged atoms
strength of electrostatic bonds depends on
distance
hydrophobic bonds
in water, water molecules push nonpolar molecules together
rank bonds in terms of strength
covalent> H bonds> electrostatic bonds> hydrophobic bonds> Van der Waals
OH bonds in water are
polar
water is
-good solvent for polar molecules and ions
what is insoluble in water
non-polar molecules
Hydrogen bonds forms between
O and N atoms
H atoms in polar bonds
water is a
charged dipole
amphipathic molecules
partly polar and partly nonpolar
fatty acids, phospholipids
fatty acids have
polar head, non-polar tail
fatty acids packed into a spherical structure in water
micelle
phospholipids have
a polar head and 2 non-polar tails
in water phospholipids form
flat sheets and form spontaneously
water weakens
hydrogen bonds and ionic bonds
water creates
hydrophobic bonds
acid is a
proton donor
base is a
proton acceptor
strong acids
dissociate completely
equilibrium very far right
weak acids and bases
exist in equilibrium with their conjugate species
molecule is an acid if
the uncharged form of a molecule is a proton donor (COOH)
molecule is a base if
the uncharged form of a molecule is a proton acceptor (NH2)
water can act as a
acid or base
in pure water
[H3O+] = [OH-]
pH equation
pH = log[H+]
higher [H+] pushes equilibrium
left
lower [H+] pulls equilibrium to the
right
small changes in [H+] have a
big effect on protein molecules
denaturation
caused by changes in protonation
Ka =
acid dissociation constant
Ka equation
Ka = [H+][A]/[HA]
Henderson- Hasselbach equations
pH = pKa + log [A]/[HA]
when pH = pKa
half of A is unprotonated, other half is unprotonated
proton exchanges between acids and bases are
spontaneous that occur rapidly
a substance can add to a buffer if
it reacts with added H+ or OH- to get rid of some of the added OH/H
buffers are
weak acids or bases
when do buffers work well
when their pH is near their pKa
most important physiological buffer
bicarbonate
what generates acidity in the body
metabolism
