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Lifes Chemical BasisLifes Chemical Basis
Spring 2012Spring 2012
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CoalCoal--fired Georgia plants lead nation in greenhousefired Georgia plants lead nation in greenhouse
gas emissions, EPA data showgas emissions, EPA data show
The Augusta ChronicleThe Augusta Chronicle By RobBy Rob PaveyPavey Staff Writer Thursday, Jan. 12,Staff Writer Thursday, Jan. 12,
20122012
The EPAs new compilation of heat-trapping gases shows that U.S. power plants
are responsible for about 72 percent of the pollution blamed for global warming,
with Southern Companys Plant Scherer in Juliette, Ga., at the top of the list that
includes about 6,700 of the nations industrial pollution sources.
Well discuss the physical, chemical, and
economic basis of this article while we studyunit 1.
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Each of us is a collection of elementsEach of us is a collection of elements
Elements are fundamental substances that consist of only one kind ofElements are fundamental substances that consist of only one kind ofatomatom
An atom is the smallest unit of an element that still retains the elementsAn atom is the smallest unit of an element that still retains the elementspropertiesproperties
Impacts, Issues:Impacts, Issues: What Are YouWhat Are You
WorthWorth
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Proportions of the most common elements in a human body, Earths crust,Proportions of the most common elements in a human body, Earths crust,and sewaterand sewater
Impacts, Issues: What Are YouImpacts, Issues: What Are You
WorthWorth
Oxygen 61.0%
Carbon 23.0
Hydrogen 10.0
Nitrogen 2.6
Calcium 1.4Phosphorus 1.1
Potassium 0.2
Sulfur 0.2
Human
Fig. 2-1b, p.19
Oxygen 85.7%
Hydrogen 10.8
Chlorine 2.0
Sodium 1.1
Magnesium 0.1Sulfur 0.1
Calcium 0.04
Potassium 0.03
Seawater
Oxygen 46.0%
Silicon 27.0
Aluminum 8.2
Iron 6.3
Calcium 5.0Magnesium 2.9
Sodium 2.3
Potassium 1.5
Earths Crust
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ElementsElements
Fundamental forms of matterFundamental forms of matter
Cant be broken apart by normalCant be broken apart by normalmeansmeans
92 occur naturally on Earth92 occur naturally on Earth
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Most Common Elements inMost Common Elements in
Living OrganismsLiving OrganismsOxygenOxygen
HydrogenHydrogen
CarbonCarbon
NitrogenNitrogen
Fig. 2-3, p.20
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What Are Atoms?What Are Atoms?
Smallest particles that retain properties ofSmallest particles that retain properties of
an elementan element
Made up of subatomic particles:Made up of subatomic particles:
Protons (+)Protons (+)
Electrons (Electrons (--))
Neutrons (no charge)Neutrons (no charge)
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Representing theRepresenting the
Hydrogen AtomHydrogen Atom
electron
proton
electron
Shell model Ball model Electron density cloud
Fig. 2-2, p.20
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Fig. 2-2a, p.20
Representing theRepresenting the
Hydrogen AtomHydrogen Atom
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electron
proton
electron
Fig. 2-2a, p.20
RepresentingRepresenting
thetheHydrogenHydrogen
AtomAtom
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Fig. 2-2c, p.20
RepresentingRepresenting
thetheHydrogenHydrogen
AtomAtom
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Atomic NumberAtomic Number
Number of protonsNumber of protons
All atoms of an element have the sameAll atoms of an element have the same
atomic numberatomic numberAtomic number of hydrogen = 1Atomic number of hydrogen = 1
Atomic number of carbon = 6Atomic number of carbon = 6
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Mass NumberMass Number
Number of protonsNumber of protons
++
Number of neutronsNumber of neutrons
Isotopes vary in mass numberIsotopes vary in mass number
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IsotopesIsotopes
Atoms of an element with differentAtoms of an element with different
numbers of neutrons (different massnumbers of neutrons (different mass
numbers)numbers)
Carbon 12 has 6 protons, 6 neutronsCarbon 12 has 6 protons, 6 neutrons
Carbon 14 has 6 protons, 8 neutronsCarbon 14 has 6 protons, 8 neutrons
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RadioisotopesRadioisotopes
Have an unstable nucleus thatHave an unstable nucleus that
emits energy and particlesemits energy and particles
Radioactive decay transformsRadioactive decay transforms
radioisotope into a different elementradioisotope into a different element
Decay occurs at a fixed rateDecay occurs at a fixed rate
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1616
Nuclear FissionNuclear Fission
? A
energyn2SrXeenergyn2RbCs
energyn3KrBa
energyn3BrLa
energyn4ZnSm
UnU
1
0
90
38
144
54
1
0
90
37
144
55
1
0
93
36
140
56
10
8735
14657
1
0
72
30
160
62
236
92
1
0
235
92
pp
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1717
Nuclear Fission ReactorsNuclear Fission Reactors
Electricity can be generated from steamElectricity can be generated from steam
heated by nuclear fission reactions.heated by nuclear fission reactions.
Greatest danger of nuclear reactors isGreatest danger of nuclear reactors iscore meltdowncore meltdown..
There have been three very seriousThere have been three very serious
nuclear reactor accidents:nuclear reactor accidents:
1.1. Three Mile Island in PA.Three Mile Island in PA.
2.2. Chernobyl in the Ukraine.Chernobyl in the Ukraine.
3. Fukushima3. Fukushima--DaichiDaichi in Japanin Japan
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Nuclear Chain Reaction, theNuclear Chain Reaction, the
VideoVideohttp://www.youtube.com/watch?v=0v8i4v1http://www.youtube.com/watch?v=0v8i4v1
mieUmieU
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CaesiumCaesium--137137
By product of the nuclear fission reactionsBy product of the nuclear fission reactions
The 2011 FukushimaThe 2011 Fukushima--DaichiDaichi nuclearnuclear
accident released Csaccident released Cs--137137CsCs--137 produces both gamma and beta137 produces both gamma and beta
radiationradiation
Potential cause of cancerPotential cause of cancerlevels of contaminants detected (in thelevels of contaminants detected (in the
US) are far below the standards observedUS) are far below the standards observed
by EPA and other U.S. agencies.by EPA and other U.S. agencies.
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Radiation Detected In Drinking Water In 13 More USRadiation Detected In Drinking Water In 13 More US
Cities, CesiumCities, Cesium--137 In Vermont Milk137 In Vermont Milk
ForbesForbes,, 4/09/2011 @ 8:15AM4/09/2011 @ 8:15AM
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CsCs--137 Map137 Map
Go to yahoo image searchGo to yahoo image search
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Radioisotopes as TracersRadioisotopes as Tracers
Tracer is substance with aTracer is substance with a
radioisotope attached to itradioisotope attached to it
Emissions from the tracer can beEmissions from the tracer can be
detected with special devicesdetected with special devices
Following movement of tracers isFollowing movement of tracers is
useful in many areas of biologyuseful in many areas of biology
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Radioisotopes in MedicineRadioisotopes in Medicine
PositronPositron--Emission Tomography (PET)Emission Tomography (PET)
uses radioisotopes to form images ofuses radioisotopes to form images of
body tissuesbody tissues Patient is injected with tracer and put through aPatient is injected with tracer and put through a
PET scannerPET scanner
Body cells absorb tracer at different ratesBody cells absorb tracer at different rates
Scanner detects radiation caused by energy fromScanner detects radiation caused by energy fromdecay of the radioisotope, and radiation then formsdecay of the radioisotope, and radiation then forms
an imagean image
Image can reveal variations and abnormalities inImage can reveal variations and abnormalities in
metabolic activitymetabolic activity
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Fig. 2-4a, p.21
Radioisotopes in MedicineRadioisotopes in Medicine
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Radioisotopes in MedicineRadioisotopes in Medicine
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detector ring inside pet scanner Portion of the patients
body being scanned
Fig. 2-4b, p.21
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The ring
intercepts
emissionsfrom the
labeled
molecules
Fig. 2-4c, p.21
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Fig. 2-4d, p.21
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Other Uses of RadioisotopesOther Uses of Radioisotopes
Drive artificial pacemakersDrive artificial pacemakers
Radiation therapyRadiation therapyEmissions from some radioisotopes canEmissions from some radioisotopes can
destroy cells. Some radioisotopes are used todestroy cells. Some radioisotopes are used to
kill small cancers.kill small cancers.
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What DeterminesWhat Determines
Whether Atoms WillWhether Atoms WillInteract?Interact?
The number and arrangementThe number and arrangement
of their electronsof their electrons
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ElectronsElectrons
Carry a negative chargeCarry a negative charge
Repel one anotherRepel one another
Are attracted to protons in the nucleusAre attracted to protons in the nucleusMove in orbitalsMove in orbitals -- volumes of space thatvolumes of space that
surround the nucleussurround the nucleus
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Electron OrbitalsElectron Orbitals
Orbitals can hold up to twoOrbitals can hold up to two
electronselectrons
Atoms differ in the number ofAtoms differ in the number of
occupied orbitalsoccupied orbitals
Orbitals closest to nucleus areOrbitals closest to nucleus are
lower energy and are filled firstlower energy and are filled first
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p.22
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OrbitalsOrbitals
FromFrom youtubeyoutube::
http://www.youtube.com/watch?v=Khttp://www.youtube.com/watch?v=K--
jNgq16jEYjNgq16jEY
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Shell ModelShell Model
First shellFirst shell
LowestLowest
energyenergy Holds 1 orbitalHolds 1 orbital
with up to 2with up to 2
electronselectrons
Second shellSecond shell
4 orbitals hold4 orbitals hold
up to 8up to 8
electronselectrons
HYDROGEN
1p+ , 1e-HELIUM
2p+ , 2e-
CARBON
6p+ , 6e-
OXYGEN
8p+ , 8e-
SODIUM
11p+ , 11e-
CHLORINE
17p+ , 17e-
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HYDROGEN
1p+ , 1e-HELIUM
2p+ , 2e-
CARBON
6p+ , 6e-OXYGEN
8p+ , 8e-
SODIUM11p+ , 11e-
CHLORINE17p+ , 17e-
Fig. 2-6, p.23
NEON
10p+ , 10e-
electron
protonneutron
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Probability ModelProbability Model
Each model is a 3-dimensional approximation of anelectron orbital
Fig. 2-5, p.22
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Electron arrangements in atoms
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Electron VacanciesElectron Vacancies
Unfilled shells make atoms likelyUnfilled shells make atoms likely
to reactto react
Hydrogen, carbon, oxygen, andHydrogen, carbon, oxygen, andnitrogen all have vacancies in theirnitrogen all have vacancies in their
outer shellsouter shells
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Chemical Bonds, Molecules,Chemical Bonds, Molecules,
& Compounds& CompoundsBond is union between electron structuresBond is union between electron structures
of atomsof atoms
Atoms bond to form moleculesAtoms bond to form moleculesMolecules may contain atoms of only oneMolecules may contain atoms of only one
elementelement -- OO22
M
olecules of compounds contain moreM
olecules of compounds contain morethan one elementthan one element -- HH22OO
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Chemical BookkeepingChemical Bookkeeping
Use symbols for elements when writingUse symbols for elements when writing
formulasformulas
Formula for glucose is CFormula for glucose is C66HH1212OO66
6 carbons6 carbons
12 hydrogens12 hydrogens
6 oxygens6 oxygens
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Chemical BookkeepingChemical Bookkeeping
Chemical equation shows reactionChemical equation shows reaction
ReactantsReactants ------> Products> Products
Equation for photosynthesis:Equation for photosynthesis:
REACTANTS PRODUCTS
6CO2
CARBONDIOXIDE
12H2O
WATER
+ C6H12O6
GLUCOSE
6H2O
WATER
+
6 carbons
12 oxygens
24 hydrogens
12 oxygens
6 carbons
12 hydrogens
6 oxygens
12 hydrogens
6 oxygens
6O2
OXYGEN
+
12 oxygens
sunlight
energy
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Chemical bookkeeping
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Important Bonds inImportant Bonds in
BiologicalM
oleculesBiologicalM
oleculesIonic BondsIonic Bonds
Covalent BondsCovalent Bonds
Hydrogen BondsHydrogen Bonds
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Ion FormationIon Formation
Atom has equal number ofAtom has equal number of
electrons and protonselectrons and protons -- no netno net
chargechargeAtom loses electron(s), becomesAtom loses electron(s), becomes
positively charged ion (positively charged ion (cationcation))
Atom gains electron(s), becomesAtom gains electron(s), becomesnegatively charged ion (anion)negatively charged ion (anion)
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Ionic BondingIonic Bonding
One atom loses electrons,One atom loses electrons,
becomes positively charged ionbecomes positively charged ion
Another atom gains theseAnother atom gains these
electrons, becomes negativelyelectrons, becomes negatively
charged ioncharged ion
Charge difference attracts theCharge difference attracts thetwo ions to each othertwo ions to each other
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Formation of NaClFormation of NaCl
Sodium atom (Na)Sodium atom (Na)
Outer shell has one electronOuter shell has one electron
Chlorine atom (Cl)Chlorine atom (Cl)
Outer shell has seven electronsOuter shell has seven electrons
Na transfers electron to Cl forming NaNa transfers electron to Cl forming Na
++
and Cland Cl--
Ions remain together as NaClIons remain together as NaCl
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Formation of NaClFormation of NaCl
electron transfer
sodium
atom
11 p +
chlorine
atom17 p +
17 e-
chlorine
ion
17 p +
18 e-
sodium
ion
11 p +
10 e-
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Electrons and ChemicalElectrons and Chemical
BondingBondingFromFrom youtubeyoutube::
http://www.youtube.com/watch?v=QqjcCvhttp://www.youtube.com/watch?v=QqjcCvzWwwwzWwww
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Fig. 2-8a(2), p.24
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Ionic and covalent bondingIonic and covalent bonding
animationanimation
http://www.youtube.com/watch?v=QqjcCvhttp://www.youtube.com/watch?v=QqjcCvzWwwwzWwww
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Covalent BondingCovalent Bonding
Atoms share a pair or pairs of electronsAtoms share a pair or pairs of electrons
to fill outermost shellto fill outermost shell
Single covalent bond
Double covalent bond
Triple covalent bond
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molecular hydrogen (H2)
HH
Two hydrogen atoms,
each with one proton,
share two electrons
in a single nonpolar
covalent bond.
Covalent BondingCovalent Bonding
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molecular oxygen (O2)O=O
Two oxygenatoms,
each with eight
protons,
share four
electrons in a
nonpolar double
covalent bond.
Covalent BondingCovalent Bonding
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water (H2O)HOH
Oxygen has
vacancies for two
electrons in its
highest energy
level orbitals. Two
hydrogen atoms
can each sharean electron with
an oxygen. The
resulting two
polar covalent
bonds form awater molecule.
Fig. 2-8b(3), p.25
Covalent BondingCovalent Bonding
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5656
Mixtures, Substances,Mixtures, Substances,
Compounds, and ElementsCompounds, and ElementsCompoundsCompounds
substances composed of two or moresubstances composed of two or more
elements in a definite ratio by masselements in a definite ratio by mass
can be decomposed into the constituentcan be decomposed into the constituent
elementselements
Water is a compound that can be decomposed intoWater is a compound that can be decomposed into
simpler substancessimpler substances hydrogen and oxygenhydrogen and oxygen
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Nonpolar Covalent BondsNonpolar Covalent Bonds
Atoms share electrons equallyAtoms share electrons equally
Nuclei of atoms have sameNuclei of atoms have samenumber of protonsnumber of protons
Example: Hydrogen gas (HExample: Hydrogen gas (H--H)H)http://www.youtube.com/watch?v=thttp://www.youtube.com/watch?v=t
Opke6cpqWY&feature=channel_viOpke6cpqWY&feature=channel_vi
deo_titledeo_title
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Polar Covalent BondsPolar Covalent Bonds
Number of protons in nuclei ofNumber of protons in nuclei ofparticipating atoms isparticipating atoms is notnotequalequal
Electrons spend more time nearElectrons spend more time nearnucleus with most protonsnucleus with most protons
WaterWater -- Electrons more attracted toElectrons more attracted toO nucleus than to H nucleiO nucleus than to H nuclei
FromFrom YoutubeYoutube::http://www.youtube.com/watch?v=1http://www.youtube.com/watch?v=1ln 81daBsln 81daBs
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Hydrogen BondingHydrogen Bonding
Molecule held together by polar covalentMolecule held together by polar covalent
bonds has nobonds has no netnetchargecharge
However, atoms of the molecule carryHowever, atoms of the molecule carrydifferent chargesdifferent charges
Atom in one polar covalent molecule canAtom in one polar covalent molecule can
be attracted to oppositely charged atom inbe attracted to oppositely charged atom inanother such moleculeanother such molecule
http://www.youtube.com/watch?v=lkl5cbfqhttp://www.youtube.com/watch?v=lkl5cbfq
FRMFRM
h d
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ExamplesExamples
ofof
HydrogenHydrogen
BondsBonds
hydrogen
bond
water
molecule
ammonia
molecule
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Properties of WaterProperties of Water
PolarityPolarity
TemperatureTemperature--StabilizingStabilizing
SolventSolventCohesiveCohesive
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Water Is a PolarWater Is a Polar
Covalent MoleculeCovalent Molecule
Molecule has no netMolecule has no net
chargecharge
Oxygen end has aOxygen end has a
slight negative chargeslight negative charge
Hydrogen end has aHydrogen end has a
slight positive chargeslight positive charge
+ +
HH
O
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Liquid WaterLiquid Water
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Fig. 2-9c, p.26
Liquid WaterLiquid Water
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Hydrophilic & HydrophobicHydrophilic & Hydrophobic
SubstancesSubstances
Hydrophilic substancesHydrophilic substances
PolarPolar
Hydrogen bond with waterHydrogen bond with water
Example: sugarExample: sugar
Hydrophobic substancesHydrophobic substances
NonpolarNonpolar
Repelled by waterRepelled by water
Example: oilExample: oil
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TemperatureTemperature--Stabilizing EffectsStabilizing Effects
Liquid water can absorb much heatLiquid water can absorb much heat
before its temperature risesbefore its temperature rises
Why?Why?
Much of the added energy disruptsMuch of the added energy disrupts
hydrogen bonding rather thanhydrogen bonding rather than
increasing the movement of moleculesincreasing the movement of molecules
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Covalent bonding animation.
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Evaporation of WaterEvaporation of Water
Large energy input can cause individualLarge energy input can cause individualmolecules of water to break free into airmolecules of water to break free into air
As molecules break free, they carry awayAs molecules break free, they carry awaysome energy (lower temperature)some energy (lower temperature)
Evaporative water loss is used byEvaporative water loss is used bymammals to lower body temperaturemammals to lower body temperature
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Why Ice FloatsWhy Ice Floats
In ice, hydrogen bonds lockIn ice, hydrogen bonds lockmolecules in a latticemolecules in a lattice
Water molecules in lattice areWater molecules in lattice arespaced farther apart then thosespaced farther apart then thosein liquid waterin liquid water
Ice is less dense than waterIce is less dense than water
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Fig. 2-9e, p.26
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Water Is a Good SolventWater Is a Good Solvent
Ions and polar molecules dissolve easilyIons and polar molecules dissolve easily
in waterin water
When solute dissolves, water moleculesWhen solute dissolves, water molecules
cluster around its ions or molecules andcluster around its ions or molecules and
keep them separatedkeep them separated
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Water CohesionWater Cohesion
Hydrogen bonding holdsHydrogen bonding holdsmolecules in liquid watermolecules in liquid watertogethertogether
Creates surface tensionCreates surface tension
Allows water to move asAllows water to move as
continuous column upwardcontinuous column upwardthrough stems of plantsthrough stems of plants
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Example of Waters CohesionExample of Waters Cohesion
Fig. 2-11a, p.27
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Example of Waters CohesionExample of Waters Cohesion
Fig. 2-11b, p.27
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Na+
Cl
+ + +
+
+
+
+
+
+
+
+
++ +
+
+
+
+
Spheres of HydrationSpheres of Hydration
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Spheres of hydration
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The pH ScaleThe pH Scale
Measures HMeasures H++ concentration of fluidconcentration of fluid
Change of 1 on scale means 10X changeChange of 1 on scale means 10X changein Hin H++ concentrationconcentration
Highest HHighest H++ Lowest HLowest H++
00------------------------------------------77--------------------------------------1414
Acidic Neutral Basic Acidic Neutral Basic
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Examples of pHExamples of pH
Pure water is neutral with pH of 7.0Pure water is neutral with pH of 7.0
AcidicAcidic Stomach acid: pH 1.0Stomach acid: pH 1.0 -- 3.03.0
Lemon juice: pH 2.3Lemon juice: pH 2.3
BasicBasic Seawater: pH 7.8Seawater: pH 7.8 -- 8.38.3
Baking soda: pH 9.0Baking soda: pH 9.0
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Fig. 2-12, p.28
The pH ScaleThe pH Scale
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Acids & BasesAcids & Bases
AcidsAcids
Donate HDonate H++ when dissolved in waterwhen dissolved in water
Acidic solutions have pH < 7Acidic solutions have pH < 7
BasesBases
Accept HAccept H++ when dissolved in waterwhen dissolved in water
Acidic solutions have pH > 7Acidic solutions have pH > 7
http://www.youtube.com/watch?v=vShCnTY1http://www.youtube.com/watch?v=vShCnTY1--
T0T0
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Weak and Strong AcidsWeak and Strong Acids
Weak acidsWeak acids
Reluctant HReluctant H++ donorsdonors
Can also accept H after giving it upCan also accept H after giving it up
Carbonic acid (HCarbonic acid (H22COCO33) is example) is example
Strong acidsStrong acids
Completely give up HCompletely give up H++ when dissolvedwhen dissolved
Hydrochloric acid (HCl) is exampleHydrochloric acid (HCl) is example
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Acid RainAcid Rain
A coal-burning power plant emits sulfur dioxide, which dissolves inwater vapor to form acid rain
Fig. 2-13, p.29
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SaltsSalts
Compounds that release ions other thanCompounds that release ions other than
HH++ and OHand OH-- when dissolved in waterwhen dissolved in water
Example: NaCl releases NaExample: NaCl releases Na++ and Cland Cl
Many salts dissolve into ions that play
Many salts dissolve into ions that playimportant biological rolesimportant biological roles
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Buffer SystemsBuffer Systems
Minimize shifts in pHMinimize shifts in pH
Partnership between weak acid and basePartnership between weak acid and baseit forms when dissolvedit forms when dissolved
Two work as pair to counter shifts in pHTwo work as pair to counter shifts in pH
Carbonic AcidCarbonic Acid BicarbonateBicarbonate
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Carbonic AcidCarbonic Acid--BicarbonateBicarbonate
Buffer SystemBuffer System
When blood pH rises, carbonic acidWhen blood pH rises, carbonic acid
dissociates to form bicarbonate and Hdissociates to form bicarbonate and H++
HH22C0C033 ----------> HC0> HC033-- + H+ H++
When blood pH drops, bicarbonate bindsWhen blood pH drops, bicarbonate binds
HH++ to form carbonic acidto form carbonic acid
HC0HC033-- + H+ H++ ----------> H> H22C0C033 Weak acidWeak acid
Weak acidBase
Base
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Fig. 2-14, p.31
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