Lifes Chemical Basis 2012

8/3/2019 Lifes Chemical Basis 2012

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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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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



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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.



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molecular oxygen (O2)O=O

Two oxygenatoms,

each with eight

protons,

share four

electrons in a

nonpolar double

covalent bond.



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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



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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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Lifes Chemical Basis 2012