AP Biology AP Biology Chemistry
AP BiologyAP Biology
Chemistry
Biology Is MultidisciplinaryBiology Is Multidisciplinary
• Emergent Properties = new properties that result from the interaction of components at a lower level of organization
– Properties NOTNOT derived by adding original properties together
• Life is emergent properties• Hierarchy of life
Elements and CompoundsElements and Compounds• Chemistry = study of matter and interactions
• All living thing are made of matter• Matter = has space and mass
• Mass = amount of matter
• Weight = measure of force of gravity on matter
Elements and CompoundsElements and Compounds
• Elements = matter that cannot be broken down into simple substances by ordinary means
– 92 natural; ? Artificial
• 96% of all life = CHON
• Other 4% = Ca, K, S, Na, Cl, Mg.
• Trace elements = minute quantities, essential to life (B, Cr, Cu, I, Fe, Mn, Sn, Zn)
Elements and CompoundsElements and Compounds• Compounds = molecules composed of 2 or more
elements chemically combined in a fixed ratio (NaCl)
• Compounds have different properties from their original elements
Atomic Structure/behaviorAtomic Structure/behavior• 2 basic parts: nucleus and electron ‘cloud’
• Nucleus = ‘center’; Protons (+1) and neutrons (0) All mass
• Electron ‘cloud’- electron(s) (-), negligible mass
Structure/behaviorStructure/behavior• Atomic mass and number are written to the left of
the symbol; mass on top
• Atomic number = number of protons (+)
• Atomic mass = no. protons (at. no.) + no. neutrons; mass number = average of all isotopes found in nature
• Isotope = same atom with different atomic mass due to differing numbers of neutrons
– May be unstable - radioactive
• Atomic mass and number are written to the left of the symbol; mass on top
• Atomic number = number of protons (+)
• Atomic mass = no. protons (at. no.) + no. neutrons; mass number = average of all isotopes found in nature
• Isotope = same atom with different atomic mass due to differing numbers of neutrons
– May be unstable - radioactive
Unstable IsotopesUnstable Isotopes
• Radiation - spontaneous decay of subatomic particles or energy
– Alpha (α), Beta (β), Gamma(γ)
– Transformation into a stable element
• Radiation may be detected
• Radiation - spontaneous decay of subatomic particles or energy
– Alpha (α), Beta (β), Gamma(γ)
– Transformation into a stable element
• Radiation may be detected
Structure/behaviorStructure/behavior
• 3 uses for radiation;
– Dating
– Tracers
– Cancer treatment
• 3 uses for radiation;
– Dating
– Tracers
– Cancer treatment
Radioactive Dating Radioactive Dating • N2 absorbs energy from cosmic radiation
– Converted into C14
– C14 spontaneously decays into C12
• Living organisms absorb N2 and stop when they die; C14 begins decaying
• Half-life = length of time it takes for half the substance to decay. Half-life is known; age can be calculated by knowing ratio of stable/radioactive isotope in fossils vs living organisms
Radiation DatingRadiation Dating
• C14’s half life = 5,700 Yr.
• Beta radiation rate = 15 rad/minute
• If the sample = 7.5 rads/min. = ½ gone or 5700 y.o.
• If the sample is ¼ gone, then the sample = 11,400 y.o.
• If 1/8 = ?
Radioactive TracersRadioactive Tracers
• Radioactive isotopes behave the same chemically
– P, N2, used to determine structure of DNA
– I2 in thyroid
• Radioactive isotopes behave the same chemically
– P, N2, used to determine structure of DNA
– I2 in thyroid
PET scan
Radiation: Cancer Radiation: Cancer
• Treatment of cancer: Co
• Cause cancer; Chernobyl, Tokaimura; 3-Mile Island?
Structure/behaviorStructure/behavior
• Energy Levels: Electrons and orbitals
• Arrangement of outer electrons (valence) determines how atoms interact with other atoms (Chemistry)
• Electrons have potential energy because of their position (potential) relative to the nucleus
• Energy Levels: Electrons and orbitals
• Arrangement of outer electrons (valence) determines how atoms interact with other atoms (Chemistry)
• Electrons have potential energy because of their position (potential) relative to the nucleus
• Energy = the ability to do work; move
• Potential = stored energy; due to position
• Energy = the ability to do work; move
• Potential = stored energy; due to position
• Kinetic = energy of motion• Kinetic = energy of motion
Energy
• Water on top of the hill = potential energy
• Energy flowing down the hill (gravity) has kinetic energy
• Water at the bottom of the hill has less potential energy
Structure/behaviorStructure/behavior
• Electron ‘shells’, ‘orbitals’ = distances that electrons are from the nucleus
• Electrons in the outer shells are more reactive and cause ‘chemical changes’
• Outer shell = ‘valence shell’
• Valence electrons = more reactive
• Electron ‘shells’, ‘orbitals’ = distances that electrons are from the nucleus
• Electrons in the outer shells are more reactive and cause ‘chemical changes’
• Outer shell = ‘valence shell’
• Valence electrons = more reactive
Energy Energy • Electrons in the atom have
potential energypotential energy– Position relative to the nucleus– Electrons farther away from the nucleus have
greater potential energy• Electrons can absorb or lose energy
BondsBonds
• Attractions of atoms or molecules to form new compounds
• Three types:
– Covalent
– Ionic
– Hydrogen
Structure/behaviorStructure/behavior
• Bonding = attractions formed between atoms caused by the interactions of valence electrons
• Number of bonds = no. of electrons gained/lost, shared to fulfill octet rule
• Bonding = attractions formed between atoms caused by the interactions of valence electrons
• Number of bonds = no. of electrons gained/lost, shared to fulfill octet rule
Structure/behaviorStructure/behavior
• Octet Rule = atoms are most stable when outer ‘shell’ has 8 electrons
• Four = do not gain or lose electrons (ions) but ‘share’
– Carbon, silicon
• Octet Rule = atoms are most stable when outer ‘shell’ has 8 electrons
• Four = do not gain or lose electrons (ions) but ‘share’
– Carbon, silicon
How Many Bonds Will Atoms How Many Bonds Will Atoms Form?Form?
•Carbon -Carbon - 4 •NitrogenNitrogen - 3•OxygenOxygen - 2 •Hydrogen - 1
What Are The Types of Bonds?What Are The Types of Bonds?
• Covalent• Ionic • Hydrogen
Covalent BondCovalent Bond
• Strongest type
• Electrons shared
• Diatomic molecules
• Carbon;
– 4 valence electrons
– May be single, double, or triple
– Si (?)
• Strongest type
• Electrons shared
• Diatomic molecules
• Carbon;
– 4 valence electrons
– May be single, double, or triple
– Si (?)
Covalent Bond
• Electrons may not be shared equally
• Polar - one atom may ‘share’ the electron(s) more; imbalanced bond
– Polar Covalent Bond
• Nonpolar Covalent Bond = (?)
Covalent bonds
Covalent BondCovalent Bond
• Polarity or non-polarity causes reactions between MOLECULES
Ionic BondsIonic Bonds
• Ionic Bond = formed between atoms that gain/lose valence electrons
• Not as strong as Covalent
• Usually only a few atoms or groups (polyatomic ions, CO3, PO4)
• Electrical charge; easily dissociated
– One cause of pH
• Ionic Bond = formed between atoms that gain/lose valence electrons
• Not as strong as Covalent
• Usually only a few atoms or groups (polyatomic ions, CO3, PO4)
• Electrical charge; easily dissociated
– One cause of pH
Ionic bonds
Ionic BondsIonic Bonds• Ions may dissociate easily (freely) in water • Causes the water to become an electrolyte• In living systems, the amount of (+) or (–)
is measured as pH• Nervous, muscular system
Hydrogen BondsHydrogen Bonds
• Attraction between (+) and (-) of adjacent molecule
• “Most” important in biology • Weakest of the three• Molecules have polar sites in
their structure
Bonds and Function and Function• Shape of the molecule created
by bonding forces determines function
• Ex. Proteins have specific shapes that allow only another molecule with the right shape to fit; – Makes life chemistry
possible
• Shape of the molecule created by bonding forces determines function
• Ex. Proteins have specific shapes that allow only another molecule with the right shape to fit; – Makes life chemistry
possible
Structure/behaviorStructure/behavior• Chemical equations are shorthand for reactions• Reactants and Products• Chemical formula vs. structural formula• Equilibrium
WaterWater
Water• Life evolved in water (oceans)• ¾ of earth covered with water• 70-90% of organisms are water• Properties of water make life possible• Philic = loving• Phobic = fearing• Hydro = water
Exists in all 3 states on the planet
Properties of WaterProperties of Water
• Adhesive
• Cohesive
• Surface tension
• High specific heat
• Expands as is freezes
• Universal solvent
Water: Hydrogen bonding
Water PropertiesWater PropertiesWater PropertiesWater Properties
• Adhesive = adheres to other substances hydrophilic substances (glass, metals)
• Cohesive = adheres to itself
• Adhesion and cohesion create Capillarity in trees (transpiration)
• Adhesive = adheres to other substances hydrophilic substances (glass, metals)
• Cohesive = adheres to itself
• Adhesion and cohesion create Capillarity in trees (transpiration)
Water- PropertiesWater- Properties
• Surface tension - beading,
• ex. waterstriders
High Specific Heat
• Heat = total kinetic energy (motion) created by moving molecules.
• calorie = amount of heat needed to raise the T of 1 g of water 1o C.
• Kilocalorie = 1000 cal.; Kcal or C• Specific heat of water is very high
– H bond absorb heat when broken and release heat when formed.
• Slow to change Temperature
• Heat = total kinetic energy (motion) created by moving molecules.
• calorie = amount of heat needed to raise the T of 1 g of water 1o C.
• Kilocalorie = 1000 cal.; Kcal or C• Specific heat of water is very high
– H bond absorb heat when broken and release heat when formed.
• Slow to change Temperature
Water: Specific Heat
• Water will act as a heat ‘sink’, traps heat during summer…
• Slowly releases heat during winter
• Moderates earth’s climate; coastal areas milder
High Heat of Vaporization
• Heat of vaporization = amount of heat energy needed to cause a liquid to evaporate; (water = 540 cal/g)
– H bonds must be broken before water molecules can absorb heat energy
• Heat of vaporization = amount of heat energy needed to cause a liquid to evaporate; (water = 540 cal/g)
– H bonds must be broken before water molecules can absorb heat energy
High Heat of Vaporization• Evaporative cooling = cooling of a surface
as a liquid evaporates• Molecules with the highest energy
evaporate fastest, – Molecules with less heat energy are left
behind (less heat = cooler) Radiators, dogs pant, Homeostasis
• Evaporative cooling = cooling of a surface as a liquid evaporates
• Molecules with the highest energy evaporate fastest, – Molecules with less heat energy are left
behind (less heat = cooler) Radiators, dogs pant, Homeostasis
Expands as it FreezesExpands as it Freezes• Water contracts as it
cools until 4oC then it expands (9%); becomes less dense (floats). Bodies of water freeze at the top; insulation for life below
• Colder water from bottom re-circulates nutrients to the surface (life)
• Water contracts as it cools until 4oC then it expands (9%); becomes less dense (floats). Bodies of water freeze at the top; insulation for life below
• Colder water from bottom re-circulates nutrients to the surface (life)
‘Universal’ Solvent
• Non-polar substances
• Due to Polarity; (+) end pulls (-) end
• Solution = mixture of two or more substances
– Air
– Solvent = dissolving agent (water); aqueous solution, alcohol – tincture
– Solute = substance being dissolved
• Non-polar substances
• Due to Polarity; (+) end pulls (-) end
• Solution = mixture of two or more substances
– Air
– Solvent = dissolving agent (water); aqueous solution, alcohol – tincture
– Solute = substance being dissolved
Measurement of SolutionsMeasurement of Solutions
• Percentage
• Molarity – measure of the amount of solute dissolved in the solvent
• pH – measure of H ions in the solution
Molarity
• Mole = 1 molecular weight dissolved in 1 liter of solvent (water)
– Ex. 1 mole of glucose = 180g dissolved in 1 liter of water. 1M glucose
• Molarity is convenient for combining substances and for describing concentration (1.0M, 0.5M, 0.1M)
• Mole = 1 molecular weight dissolved in 1 liter of solvent (water)
– Ex. 1 mole of glucose = 180g dissolved in 1 liter of water. 1M glucose
• Molarity is convenient for combining substances and for describing concentration (1.0M, 0.5M, 0.1M)
pH
• Measure of amount of H+ in solution
• Range of measure from 1-14
• 1-7 = ‘acid’
• 7-14 = ‘base’, ‘alkaline’ (alkalinity)
• Measure of amount of H+ in solution
• Range of measure from 1-14
• 1-7 = ‘acid’
• 7-14 = ‘base’, ‘alkaline’ (alkalinity)
pH
• In water, (H20) a hydrogen atom may dissociate from the oxygen to form:
H2O + H2O H30+ + OH-
H30+ = (hydronium)
OH- = hydroxide
pHpHpHpH
• In ‘pure’ water, the amount of H3O+ = OH- :
H2O + H2O H3O+ + OH-
• Equilibrium (not ionized)
• In ‘pure’ water, the amount of H3O+ = OH- :
H2O + H2O H3O+ + OH-
• Equilibrium (not ionized)
pH
In equilibrium, number of H+ in solution = 1/10,000,000
• 10-7
• 7
• Equilibrium = pH 7 = ‘neutral’
• ‘p’ = concentration
• pH = concentration of H+
pH
• In equilibrium: • H+ = 10-7 (1/10,000,000)• OH- = 10-7 (1/10,000,000)• Total of H+ + OH- = 10-14 (14)• If H+ = 1/1,000,000 = 10-6 (6)• OH- = 10-8
pH
• A change in pH number (7 to 6) is exponential (tenfold)
• 1/10,000,000 (1 in 10 million) to: 1/1,000,000 (1 in 1 million)
• 7 to 5 = 100 fold increase in H+• 5.5 to 8.5 = 1000x increase (major change)
– Pollution
pH
• Acids (‘acidic’) are substances that cause water to release H+ in solution (lower pH)
• Bases (alkaline) release OH- in solution• pH always totals 14; if pH = 5 then
concentration of OH = (?)• If pH = 9, then concentration of OH (?)
pH• Most biotic solutions = 6-8;
– Stomach = 1.5-2• Acid rain
• SO2, NO2 mix w/ water in atmosphere– Lowers pH of lakes, soil
pHpH
• Buffers = substance that prevents sudden, large changes in pH, weak acids or bases (bicarbonate)
Properties of WaterProperties of WaterProperties of WaterProperties of Water
• Cohesive; H bond• Adhesive; H bond• High specific heat; H bond• High heat of vaporization; H bond• Expands as it freezes• ‘Universal’ solvent; polarity