Chpt 1-chemistry Flashcards
micro prefix
u=1x10^-6
nano prefix
n=1x10^-9
pico prefix
p=1x10^-12
Covalent Bonds
- def
- energy
- length
Sharing a pair of electrons Energy-355 KJ'mol length C-C bond 1.54A C=C bond 1.34A CtripleC 1.20
STRONG interaction do not break spontaneously under physiological conditions
Hydrogen Bonds
- def
- energy
- length
Sharing of H atom, H has to be shared with N, O, or F
Energy- 4-20 KJ/mol
Length- 1.5-2.6A
Ionic Interaction (Electrostatic Interactions)
- def
- energy
- length
Attraction of opposite charges (partial positive/negative)
Energy-5.8
Length-Varies
Van der Waals interactions
- def
- energy
- length
interaction of electron clouds
Energy- 2-4
Length-N/A
Hydrophobic interactions
- def
- energy
- length
interaction of non polar substances
Energy-very weak
length-N/A
When is Hydrogen bonding the strongest?
Strongest when atoms are in a straight line:
- in DNA, h-bonding holds together complementary strands
- In proteins, H bonds stabilize alpha helixes and beta sheets
Ionic bonds are important where?
at active sites of enzymes
Most important compound in biochem?
WATER
Facts about H20
-70% of cell’s mass
-has unique properties–>matrix of life
1)BP of water is 100 C
2) MP of water is 0 C
3) High Specific Heat
4) High high (enthalpy) of Vaporization (delta H)
5)Universal Solvent
6)High Surface Tension
7) Density of Solid Water (ICE) is less than density of liquid water
8)Water Ionizes
H2O H+ + OH-
Specific Heat
measure of the amount of heat required to raise the temp of one g of water 1 degree C
Heat (enthalpy) of vaporization
amount of heat required to convert a liquid to a gas (phase change)
Solution
uniform molecular mixture of two or more substances
Solvent
solvent in the greatest quantity
Solute
substance in lesser quantity
substances are categorized depending on there interaction with water; what are the categories?
hydrophilic (water loving)
-dissolves in water
Hydrophobic (water fearing)
-poorly soluble in water
Surface tension
the measure of how difficult it is to break the surface of the liquid
Describe water and its high surface tension
Water is:
- Cohesive- attractive to self
- Adhesive- attractive to surfaces
Why is water so important to life?
- water is a liquid at physiological temperatures
- water has an unusually high boiling point for its molecular weight
- Water is a good thermal regulator. Large amount of heat is required to change its temperature
- water provides very effective heat dissipationf
Why does water have such unusual properties?
- Shape of molecule
- Hydrogen Bond–> weak intermolecular bond formed between partial positive of the H and partial negative of Oxygen
- -> millisecond duration
- -> requires energy to break
Hydrogen bonds in water explains:
- High Boiling Point/Freezing point
- High heat of vaporization
- Universal Solvent
- High surface tension adhesive/cohesive forces
- Density of solid water (ice) is less than density of solid liquid
Four formulas to convert between pH, pOH, [H+], & [Oh-]
1x10^-14=[H+][OH-]
14=pH + pOH
pOH= -log [OH-]
pH= -log [H+]
Proton
H+
Hydronium Ion
H3O+
Hydrogen atom
H.
Hydride
H: or H-
Hydrogen gas or molecule
H2 or H:H
Hydroxide
OH-
pH scale
-measure of [H+]
-continuous logarithmic scale 0-14
pH=7 is neutral
pH=0-6.99 acidic
pH= 7.01-14 basic
-one pH change represents 10 fold change in [H+]
pH and [H+] of human blood
pH=7.35-7.45
[H+]= 40nM
Strong Acids
dissociate 100%
-release all possible protons [H+]
Weak Acids
do not dissociate 100%
what are the Strong acids you need to know
HCl. hydrochloric acid HBr. hydrobromic acid HI. hydroiodic acid HNO3 nitric acid HClO4 perchloric acid H2SO4 sulfuric acid
Strong Bases
Dissociate 100% In water
Weak Bases
dissociates less than 100% in water
Weak Bases you need to know
Group I:
LiOH. Lithium Hydroxide
NaOH Sodium Hydroxide
KOH Potassium Hydroxide
Group II: 2 OH ions
Ca(OH)2 Calcium Hydroxide
Sr(OH)2 Strontium Hydroxide
Ba(OH)2 Barium Hydroxide
Buffer
- def
- who?
- How does a buffer work
substance that resists pH changes in a solution thus stabilizing its relative pH
- weak acids and conjugate bases
- buffer works one unit either side of pka (buffering range)
What is a buffer in our blood?
Carbonic acid (weak acid)- H2CO3
H2CO3 H+ + HCO3-
Henderson Hasselbalch equation
pH=pKa + log [Base/Acid]
Thermodynamics def
Is the study of the effects of work, heat, and energy on a system
Thermodynamics: System and Surroundings Def
System- part of the universe you are interested in studying
Surroundings- areas outside of the system
Types of systems and def
isolated system- system that does not exchange matter or energy with its surroundings
closed system- system that exchanges energy with surroundings but not matter
Open system- system that exchanges energy and matter with surrounds
What type of system (from thermo) do humans use?
Open system
-ingest food/give off waste
Entropy
S
-Disorder or randomness
Enthalpy
H
-Heat content
Temperature
T
-Kelvin
Gibbs Free Energy
G
Thermodynamics formulas
Total Energy= Usable Energy + Unusable Energy
Enthalpy(H)= Free Energy (G)+ Temp(T)Entropy(S)
Or H=G+TS
Solve for G
G=H-TS
**we can not measure G, H, or S directly thus delta or change multiplied through
deltaG=deltaH-TdeltaS
Thermodynamics:
Zeroth Law
If two systems are in thermal equilibrium with a third System, they must be in thermal equilibrium with each other
-Defines temperature (T) and thermodynamic equilibrium
If A=B and B=C, thus A must equal C
Thermodynamics:
First Law
Total energy of a system and its surrounds is constant
other ways to state:
-the energy content of the universe is constant
-energy can be neither created nor destroyed. it can only change forms
Defines heat, work, and energy
Thermodynamics:
Second Law
The entropy of any isolated system never decreases. Such systems spontaneously evolve towards thermodynamic equilibrium– The state of maximum entropy (S) of the system
or in other terms:
-the total ENTROPY (S) of a system plus that of its surrounds always increases
-entropy is a measure of randomness or disorder
Thermodynamics:
Third Law
As temperature approaches absolute zero, the entropy of a system approaches a constant minimum
or in other terms:
-the entropy of a perfect crystal at absolute zero is zero
Gibbs Free Energy (delta G)
- equation
- Rxns with Delta G +/-
DeltaG=DeltaH- TDeltaS
Rxns with a -DeltaG occur spontaneously
Rxns with a +DeltaG are NONspontaneous
Thermodynamics: Living Organism
Living organisms exist in a dynamic steady state NEVER AT EQUILIBRIUM with their surrounds
- maintaining steady state requires an input of E
- Equilibrium=death
Living organisms are open systems
- Organisms take up matter/energy
- change energy into
1) Useful energy–>cellular work: chemical synthesis, mechanical work, gradients (osmotic and electrical), Light production, Genetic information transfer
2) Heat
3) Metabolic Products- CO2, NH3, H2O, HPO42- (increases entropy in surrounds)
4) synthesize complex polymers (macromolecules)–> decreases entropy in the system
