Chemistry 4362

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Chemistry 4362Advanced Inorganic ChemistryAdvanced Inorganic Chemistry

Instructor: Dr. Byron K. ChristmasDr. Byron K. Christmas

Class Time: Tue & Thur - 5:29 to 6:49 p.m.Tue & Thur - 5:29 to 6:49 p.m.

Classroom: N-936 N-936 C-320C-320

Phone: (713) 221-8169(713) 221-8169 FAX: (713) 221-8528(713) 221-8528

E-Mail: [email protected]@uhd.edu

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IntroductionWhat is Inorganic Chemistry ?What is Inorganic Chemistry ?

• ““The chemistry of The chemistry of everythingeverything that is that is NOTNOT organic…” organic…”

• ““The chemistry of The chemistry of allall of the elements and their compounds of the elements and their compounds exceptexcept for the hydrocarbons and their derivatives.” for the hydrocarbons and their derivatives.”

• ““The branch of chemistry falling between and overlappingThe branch of chemistry falling between and overlapping with physical chemistry and organic chemistry.”with physical chemistry and organic chemistry.”

• ““What Inorganic Chemists Do!”What Inorganic Chemists Do!”

• Your Personal Definition??Your Personal Definition??

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What Do Inorganic Chemists Do ?

• Synthesize and characterize substances other Synthesize and characterize substances other than those that are clearly “organic”.than those that are clearly “organic”.

• Determine the structures of inorganic substances.Determine the structures of inorganic substances.

• Investigate the chemical reactions of inorganic substances.Investigate the chemical reactions of inorganic substances.

• Investigate the physical properties of inorganic substances.Investigate the physical properties of inorganic substances.

.• Develop hypotheses and theories to explain and systematizeDevelop hypotheses and theories to explain and systematize the empirical data collected.the empirical data collected.

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Why Should You Study Inorganic Chemistry ?Why Should You Study Inorganic Chemistry ?

• Essentially the entire universe is Inorganic.Essentially the entire universe is Inorganic.

Elemental Composition of the Sun and the UniverseSun Universe

Hydrogen 92.5 % 90.87 %Helium 7.3 % 9.08 %All Others 0.2 % 0.05 %

• The Earth is predominantly InorganicThe Earth is predominantly Inorganic.

Elemental Composition of the Earth’s Crust

Oxygen 45.5 % Iron 6.20 %Silicon 27.2 % Calcium 4.66 % Aluminum 8.30 % All Others 8.14 %

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• Inorganic materials are an essential part of our Inorganic materials are an essential part of our national economy. national economy.

U.S. Production of Top 10 Chemicals (x 10U.S. Production of Top 10 Chemicals (x 1099 lb.) - 1997 lb.) - 1997

Sulfuric AcidSulfuric Acid 95.5895.58

NitrogenNitrogen 82.88*82.88*

OxygenOxygen 64.84*64.84*

EthyleneEthylene 51.0851.08

LimeLime 42.5642.56

AmmoniaAmmonia 38.3938.39

PropylenePropylene 27.5327.53

Phosphoric AcidPhosphoric Acid 26.8326.83

Ethylene DichlorideEthylene Dichloride 26.2926.29

SulfurSulfur 26.2426.24From C&EN, June 29, 1998From C&EN, June 29, 1998

*Calculated from “billion cubic feet at STP”*Calculated from “billion cubic feet at STP”

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2000 RANK(by mass)

CHEMICAL 2000 PRODUCTION(in 109 kg)

FORMULA PRODUCTION(in moles)

RANK(by moles)

1 Sulfuric acid 39.62

2 Ethylene 25.15

3 Lime 20.12

4 Phosphoric acid 16.16

5 Ammonia 15.03

6 Propylene 14.45

7 Chlorine 12.01

8 Sodium hydroxide 10.99

9 Sodium carbonate 10.21

10 Ethylene chloride 9.92

11 Nitric acid 7.99

12 Ammonium nitrate 7.49

13 Urea 6.96

14 Ethylbenzene 5.97

15 Styrene 5.41

16 Hydrogen chloride 4.34

17 Ethylene oxide 3.87

18 Cumene 3.74

19 Ammonium sulfate 2.60

20 1,3-Butadiene 2.01

http://scifun.chem.wisc.edu/chemweek/Sulf&top/Sulf&Top.html

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U.S. Production of Top 50 Chemicals (x 10U.S. Production of Top 50 Chemicals (x 1099 lb.) - lb.) - 19941994

Total OrganicsTotal Organics 279.17279.17Total InorganicsTotal Inorganics 450.19450.19Grand TotalGrand Total 729.36729.36

• Inorganics are essential to life.Inorganics are essential to life. Water is essential for all life.Water is essential for all life. About 30 different elements are believed to be About 30 different elements are believed to be essential to life - 28 in addition to carbon andessential to life - 28 in addition to carbon and hydrogen.hydrogen.

• For all practical purposes, Inorganic Chemistry For all practical purposes, Inorganic Chemistry ISIS chemistry - chemistry - the study of the properties, composition, the study of the properties, composition,

and structure of matter, the physical and chemical and structure of matter, the physical and chemical changes it undergoes, and the energy liberated or changes it undergoes, and the energy liberated or absorbed during those changes.absorbed during those changes.

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Approaches to the Study of Inorganic ChemistryApproaches to the Study of Inorganic Chemistry

• Empirical Approach Empirical Approach (Descriptive Chemistry)(Descriptive Chemistry)

Historically this was the way it was taught. It involves essentially all memorization. It is necessary for a complete understanding of Chemistry.

• Theoretical ApproachTheoretical Approach It provides a framework for understanding the “why” of descriptive chemistry. It can provide “intellectual satisfaction”. It is limited in its ability to give explanations for all observed phenomena. It has dominated the teaching of Inorganic Chemistry for over 30 years.

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Introduction to Descriptive ChemistryIntroduction to Descriptive Chemistry

Definition: Definition: “…the study of the composition, structure,and properties of matter….” - the facts facts about theabout theelements and their compounds.elements and their compounds.

Comments from the Experts: Comments from the Experts: “…evident differencesbetween this and previous editions…is the absence of muchtheoretical material previously included…the continuingrapid growth of chemistry…required the addition of impor-tant new factsfacts to all of the descriptive material…over theyears, become less persuaded of the value of certain types oftheorizing….Thus, we felt obliged to make space for facts facts atthe expense of theoretical material.” Cotton and Wilkinson,Cotton and Wilkinson,Advanced Inorganic Chemistry, Advanced Inorganic Chemistry, 5th Edition, 1988.5th Edition, 1988.

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Comments from the Experts: Comments from the Experts: “The facts concerningthe properties and reactions of substances are the veryessence of chemistry. Facts undergo little if anychange in contrast to constantly changing theories.Moreover, …a chemist needs a solid background offacts in order to appreciate the need for theories….”R. J. Gillespie in the Forward of R. J. Gillespie in the Forward of Chemistry of theChemistry of theElementsElements, Greenwood and Earnshaw, 1st Edition,, Greenwood and Earnshaw, 1st Edition,1984.1984.

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“Over the years, the theoretical part tended to grow at the expense ofthe descriptive material….The theoretical part tended to become theend rather than the means….By the 1970’s many teachers had toabandon any attempt to cover descriptive inorganic chemistry in thetraditional sense. Thus we can encounter the student who canwrite an erudite account of structural minutiae in copper(II)chemistry, ligand field spectra and…,but who knows little aboutthe more mundane compounds of the transition elements andwould be hard pressed to locate indium in the Periodic Table, letalone venture anything about its chemistry.” Derek W. Smith,Derek W. Smith,Inorganic Substances: A Prelude to the Study of DescriptiveInorganic Substances: A Prelude to the Study of DescriptiveInorganic Chemistry, Inorganic Chemistry, 1st Edition, 1990.1st Edition, 1990.

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“Chemistry has always been, and still is, a practical subject….AnAmerican professor told me he divided inorganic chemistry books into two types: theoretical and practical. In deciding how to classify anyparticular book, he first looked to see if the extraction of the two mostproduced metals (Fe and Al) was adequately covered, what impuritieswere likely to be present, and how the processing was adapted to re-move them. Second, he looked to see if the treatment of the bondingin xenon compounds and ferrocene was longer than that of the pro-duction of ammonia. Third, he looked to see if the production and uses of phosphates were covered adequately….For some years therehas been a trend for chemistry teaching to become more theoretical.There is always theoretical interest in another interesting oxidationstate or another unusual complex, but the balance of this book istilted to ensure that they do not exclude the commonplace, the mun-dane and the commercially important.” J. D. Lee, J. D. Lee, Concise InorganicConcise InorganicChemistryChemistry, 5th Edition,, 5th Edition, 1996.1996.

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• Industrial Applications ApproachIndustrial Applications Approach

Few schools other than chemical engineering programs have used this approach. It is of great “practical” importance for students preparing for industry. It is of limited utility in preparing for graduate work in chemistry.

• Balanced ApproachBalanced Approach

Provides a balance among all approaches. Applicable to “survey-type” course. Useful for either graduate school or industry preparation. Used in THIS COURSE!!

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Course Overview• Introduction to Inorganic PolymersIntroduction to Inorganic Polymers• Theoretical Concepts Theoretical Concepts

Atomic Structure & the Periodic TableAtomic Structure & the Periodic Table Properties of the ElementsProperties of the Elements Introduction to Chemical BondingIntroduction to Chemical Bonding The Covalent BondThe Covalent Bond The Metallic BondThe Metallic Bond The Ionic BondThe Ionic Bond Intermolecular Attractive ForcesIntermolecular Attractive Forces Inorganic Thermodynamics and KineticsInorganic Thermodynamics and Kinetics Solvent Systems and Acids and BasesSolvent Systems and Acids and Bases Oxidation/ReductionOxidation/Reduction

• Descriptive Chemistry and Industrial ApplicationsDescriptive Chemistry and Industrial Applications

• Student PresentationsStudent Presentations

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Introduction to Inorganic PolymersIntroduction to Inorganic Polymers(Page 338 in Text)(Page 338 in Text)

Questions to Ponder:

1. Would you know an Inorganic Polymer if you saw one?2. How could you determine if an inorganic material was, in fact, “polymeric”?3. List important types of Inorganic Polymers.4. How would you determine what is and what is NOT an Inorganic Polymer?

Is NaCl a Polymer? Is Graphite a Polymer? What about Diamond?Is Aluminum a Polymer? What about Window Glass?

5. What general principles of chemical bonding, atomic size, etc. lead to effective polymer formation for different types of elements?6. What are commercially important inorganic polymers?

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Introduction to Inorganic PolymersIntroduction to Inorganic Polymers

Catenation – What are the requirements?Catenation – What are the requirements?

Valence of two or more?Valence of two or more? Bond energies?Bond energies? What else?What else?

HomocatenationHomocatenation

HeterocatenationHeterocatenation

Bond Energies – kJ/moleBond Energies – kJ/moleC-CC-C 356356Si-SiSi-Si 222222Ge-GeGe-Ge 188188Sn-SnSn-Sn 167167Pb-PbPb-Pb 87 87S-SS-S 251251P-PP-P 201201O-OO-O 142142Si-OSi-O 460460Sn-OSn-O 544544Al-OAl-O 586586Si-NSi-N 355355B-NB-N 460460

Bond Bond DD (kJ/mol) (kJ/mol) r (pm)r (pm)

Si-Si Si-Si 222 222 233 233

Si-N Si-N 355 355

Si-O Si-O 452 452 163 163

Si-S Si-S 293 293 200 200

Si-F Si-F 565 565 160 160

Si-Cl Si-Cl 381 381 202 202

Si-Br Si-Br 310 310 215 215

Si-I Si-I 234 234 243 243

Ge-Ge Ge-Ge 188 188 241 241

Ge-N Ge-N 257 257

Ge-F Ge-F 470 470 168 168

Ge-Cl Ge-Cl 349 349 210 210

Ge-Br Ge-Br 276 276 230 230

Ge-I Ge-I 212 212

Sn-F Sn-F 414 414

Sn-Cl Sn-Cl 323 323 233 233

Sn-Br Sn-Br 273 273 250 250

Sn-I Sn-I 205 205 270 270

Pb-F Pb-F 331 331

Pb-Cl Pb-Cl 243 243 242 242

Pb-Br Pb-Br 201 201

Pb-I Pb-I 142 142 279 279

http://chemviz.ncsa.uiuc.edu/content/doc-resources-bond.html

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Introduction to Inorganic PolymersIntroduction to Inorganic Polymers

Questions?Questions?

Assignments!Assignments!Study Hand-outs and your text on Inorganic PolymersStudy Hand-outs and your text on Inorganic Polymers

Find three to five ADDITIONAL references on the WebFind three to five ADDITIONAL references on the Web and study themand study them

Prepare for next Thursday’s Silicone laboratoryPrepare for next Thursday’s Silicone laboratory(Page 176 in Lab Manual)(Page 176 in Lab Manual)

Polysulfide Demonstration/ExperimentPolysulfide Demonstration/Experiment

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Theoretical ConceptsTheoretical ConceptsChapter 1Atomic Structure & the Periodic TableAtomic Structure & the Periodic TableProperties of the Elements Properties of the Elements Introduction to Chemical BondingIntroduction to Chemical Bonding The Ionic BondThe Ionic Bond The Covalent BondThe Covalent Bond The Metallic BondThe Metallic Bond Intermolecular Attractive ForcesIntermolecular Attractive Forces ThermodynamicsThermodynamics Acids and BasesAcids and Bases Oxidation/ReductionOxidation/Reduction

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ATOMIC STRUCTUREATOMIC STRUCTUREDefinition of Chemistry:

The study of the properties, composition, andSTRUCTURESTRUCTURE of matter, the physical and chemical changes it undergoes, and the energyliberated or absorbed during those changes.

The foundation for the STRUCTURESTRUCTURE of inorganicmaterials is found in the STRUCTURESTRUCTURE of the atom.

Atomic Structure

Molecular Structure

Bulk Structure

Material PropertiesMaterial Properties

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ATOMIC STRUCTUREATOMIC STRUCTUREHistorical Development:

Greek Concepts of MatterGreek Concepts of Matter

Aristotle - Matter is continuous, infinitelydivisible, and is composed of only 4 elements:

Earth, Air, Fire, and WaterEarth, Air, Fire, and Water

Won the philosophical/political battle. Dominated Western Thought for Centuries. Seemed very “logical”. Was totally WRONG!!WRONG!!

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ATOMIC STRUCTUREATOMIC STRUCTURE

The “Atomists” (DemocritusDemocritus, Lucippus,Epicurus, et. al.) - Matter consists ultimatelyof “indivisible” particles called “atomos” thatcanNOT be further subdivided or simplified.If these “atoms” had space between them,nothing was in that space - the “void”.

Lost the philosophical/political battle. Lost to Western Thought until 1417. Incapable of being tested or verified. Believed the “four elements” consisted of “transmutable” atoms. Was a far more accurate, though quite imperfect “picture” of reality.

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ATOMIC STRUCTUREATOMIC STRUCTUREModern Concepts of MatterModern Concepts of Matter

John Dalton (1803) - An atomist who formalizedthe idea of the atom into a viable scientific theoryin order to explain a large amount of empiricaldata that could not be explained otherwise.

Matter is composed of small “indivisible” particles called “atoms”. The atoms of each element are identical to each other in mass but different from the atoms of other elements. A compound contains atoms of two or more elements bound together in fixed proportions by mass.

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ATOMIC STRUCTUREATOMIC STRUCTURE A chemical reaction involves a rearrangement of of atoms but atoms are not created nor destroyed during such reactions.

Present Concepts - An atom is an electricallyneutral entity consisting of negatively chargedelectrons (e-) situated outside of a dense, posi-tively charged nucleus consisting of positivelycharged protons (p+) and neutral neutrons (n0).

ParticleParticle ChargeCharge MassMassElectronElectron - 1 - 1 9.109 x 10 9.109 x 10 -28 -28 ggProtonProton +1 +1 1.673 x 10 1.673 x 10 -24 -24 ggNeutronNeutron 0 0 1.675 x 10 1.675 x 10 -24 -24 gg

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e- e-p+no

no p+

NucleusNucleus

Electron CloudElectron Cloud

Model of aModel of aHelium-4Helium-4

((44He) atomHe) atom

How did we get this concept? - This portion of ourprogram is brought to you by:

Democritus, Dalton, Thompson, Planck, Einstein, Millikan, Democritus, Dalton, Thompson, Planck, Einstein, Millikan, Rutherford, Bohr, de Broglie, Heisenberg, Schrödinger, Rutherford, Bohr, de Broglie, Heisenberg, Schrödinger, Chadwick, and many others.Chadwick, and many others.

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ATOMIC STRUCTUREATOMIC STRUCTUREDemocritus - First atomic ideasDalton - 1803 - First Atomic Theory J. J. Thompson - 1890s - Measured the charge/mass

ratio of the electron (Cathode Rays)

+

Anode

_

Cathode

Electric FieldSource (Off)

FluorescentMaterial

With the electric field off, the cathode ray is not deflected.With the electric field off, the cathode ray is not deflected.

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Cathode

Anode Electric FieldSource (On)

FluorescentMaterial

-

+ +

-

With the electric field on, the cathode ray is deflectedWith the electric field on, the cathode ray is deflectedaway from the negative plate. The stronger the electricaway from the negative plate. The stronger the electricfield, the greater the amount of deflection.field, the greater the amount of deflection.

Cathode

Anode

-

+Magnet

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ATOMIC STRUCTUREATOMIC STRUCTUREWith the magnetic field present, the cathode ray isWith the magnetic field present, the cathode ray isdeflected out of the magnetic field. The stronger thedeflected out of the magnetic field. The stronger themagnetic field, the greater the amount of deflection.magnetic field, the greater the amount of deflection.

e/m = E/He/m = E/H22rr

e = the charge on the electronm = the mass of the electronE = the electric field strengthH = the magnetic field strengthr = the radius of curvature of the electron beam

Thompson, thus, measured the charge/mass ratioThompson, thus, measured the charge/mass ratioof the electron - of the electron - 1.759 x 101.759 x 1088 C/g C/g

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ATOMIC STRUCTUREATOMIC STRUCTURESummary of Thompson’s Findings:

Cathode rays had the same properties no matterCathode rays had the same properties no matter what metal was being used.what metal was being used.

Cathode rays appeared to be a constituent of allCathode rays appeared to be a constituent of all matter and, thus, appeared to be a “sub-atomic”matter and, thus, appeared to be a “sub-atomic” particle.particle.

Cathode rays had a negative charge.Cathode rays had a negative charge.

Cathode rays have a charge-to-mass ratioCathode rays have a charge-to-mass ratio of 1.7588 x 10of 1.7588 x 1088 C/g. C/g.

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ATOMIC STRUCTUREATOMIC STRUCTURER. A. Millikan - Measured the charge of the electron.

In his famous “oil-drop” experiment, Millikan was able toIn his famous “oil-drop” experiment, Millikan was able todetermine the charge on the electron independently of itsdetermine the charge on the electron independently of itsmass. Then using Thompson’s charge-to-mass ratio, hemass. Then using Thompson’s charge-to-mass ratio, hewas able to calculate the mass of the electron.was able to calculate the mass of the electron.

e = 1.602 10 x 10e = 1.602 10 x 10-19-19 coulomb coulombe/m = 1.7588 x 10e/m = 1.7588 x 1088 coulomb/gram coulomb/gramm = 9.1091 x 10m = 9.1091 x 10-28 -28 gramgram

Goldstein - Conducted “positive” ray experiments thatlead to the identification of the proton. The chargewas found to be identical to that of the electron and

the mass was found to be 1.6726 x 101.6726 x 10-24-24 g. g.

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ATOMIC STRUCTUREATOMIC STRUCTUREErnest Rutherford - Developed the “nuclear” modelof the atom.

The Plum Pudding Model of the atom:The Plum Pudding Model of the atom:

- - - - - - - - - - - - - - -+

+ +

+++

+

++

+ A smeared out “pudding”of positive charge withnegative electron “plums”imbedded in it.

The Metal Foil Experiments:The Metal Foil Experiments:

RadioactiveMaterial inPb box.

MetalFoil

FluorescentScreen-particles-particles

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ATOMIC STRUCTUREATOMIC STRUCTUREIf the plum pudding model is correct, then all ofthe massive -particles should pass right throughwithout being deflected.

In fact, most of the In fact, most of the - particles DID pass right - particles DID pass rightthrough. However, a few of them were deflected atthrough. However, a few of them were deflected athigh angles, disproving the “plum pudding” model.high angles, disproving the “plum pudding” model.

Rutherford concluded from this that the atom con-Rutherford concluded from this that the atom con-sisted of a very dense nucleus containing all of the sisted of a very dense nucleus containing all of the positive charge and most of the mass surrounded bypositive charge and most of the mass surrounded byelectrons that orbited around the nucleus much aselectrons that orbited around the nucleus much asthe planets orbit around the sun.the planets orbit around the sun.

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ATOMIC STRUCTUREATOMIC STRUCTUREAssignment:Assignment:Assume the diameter of the nucleus of a hydrogenatom is 1 x 10 -13 cm and the diameter of the atomis 1 x 10 -8 cm.

1. Calculate the volume of the nucleus and the volume of the atom in cm3 .

2. Calculate the volume of empty space in the atom.

3. Calculate the ratio of the volume of the nucleus to volume of the whole atom.

4. Calculate the density of the nucleus if the proton’s mass is 1.6726 x 10-24 g

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ATOMIC STRUCTUREATOMIC STRUCTUREProblems with the Rutherford Model:Problems with the Rutherford Model:

It was known from experiment and electromagnetictheory that when charges are accelerated, theycontinuously emit radiation, i.e., they loose energycontinuously. The “orbiting” electrons in the atomwere, obviously, not doing this.

The atoms were NOT collapsing.

Atomic spectra and blackbody radiation were known to be DISDIScontinuous.

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ATOMIC STRUCTUREATOMIC STRUCTUREAtomic Spectra - Atomic Spectra - Since the 19th century, it hadSince the 19th century, it hadbeen known that when elements and compoundsbeen known that when elements and compoundsare heated until they emit light (glow) they emit are heated until they emit light (glow) they emit that light only at discrete frequencies, giving a that light only at discrete frequencies, giving a line spectrumline spectrum..

++

--

HydrogenGas Line Spectrum

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ATOMIC STRUCTUREATOMIC STRUCTUREWhen white light is passed through a sample ofWhen white light is passed through a sample ofthe vapor of a substance, only discrete frequenciesthe vapor of a substance, only discrete frequenciesare absorbed, giving an are absorbed, giving an absorption ban spectrumabsorption ban spectrum..These frequencies are identical to those of the These frequencies are identical to those of the line spectrum of the same element or compound.line spectrum of the same element or compound.

For hydrogen, the spectroscopists of the 19thCentury found that the lines were related by the Rydberg equation:

c = R[(1/mc = R[(1/m22) - (1/n) - (1/n22)] )]

frequency

c = speed of lightR = Rydberg Constantm = 1, 2, 3, ….

n = (m+1), (m+2), (m+3), ….

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ATOMIC STRUCTUREATOMIC STRUCTUREMax Planck - In 1900 he was investigating the nature of black body radiation and tried to interpret hisfindings using accepted theories of electromagneticradiation (light). He was NOT successful since thesetheories were based on the assumption that light hadWAVE WAVE characteristics.

To solve the problem he postulated that light wasemitted from black bodies in discrete packets hecalled “quanta”. Einstein later called them“photons”. By assuming that the atoms of the blackbody emitted energy only at discrete frequencies, hewas able to explain black body radiation.

E = hE = h

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ATOMIC STRUCTUREATOMIC STRUCTUREBoth spectroscopy and black body radiationBoth spectroscopy and black body radiationindicated that atoms emitted energy only at indicated that atoms emitted energy only at discrete frequencies or energies rather thandiscrete frequencies or energies rather thancontinuously.continuously.

Is light a particle or a wave??Is light a particle or a wave??

Why do atoms emit only discrete energies?Why do atoms emit only discrete energies?

What actually happens when light interactsWhat actually happens when light interactswith matter?with matter?

What was wrong with Rutherford’s Model?What was wrong with Rutherford’s Model?

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ATOMIC STRUCTUREATOMIC STRUCTURENiels Bohr - Bohr corrected Rutherford’s modelof the atom by formulating the following postulates:

Electrons in atoms move only in discrete orbitsaround the nucleus.

When in an orbit, the electron does NOT emitenergy.

They may move from one orbit to another but areNEVER residing in between orbits.

When an electron moves from one orbit toanother, it absorbs or emits a photon of light with aspecific energy that depends on the difference inenergy between the two orbits.

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+

LymanSeries

BalmerSeries

PaschenSeries

The Bohr Model of the AtomThe Bohr Model of the Atom

(Visible)

(IR)

(UV)

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ATOMIC STRUCTUREATOMIC STRUCTURE The lowest possible energy state for an electronis called the GROUND STATEGROUND STATE. All other statesare called EXCITED STATESEXCITED STATES.

EEnn = (- 2.179 x 10 = (- 2.179 x 10-18-18 J)/n J)/n22

EEphotonphoton = E = Ehighhigh - E - Elowlow

EEphotonphoton = [(- 2.179 x 10 = [(- 2.179 x 10-18-18 J)/n J)/n22highhigh]]

-[(- 2.179 x 10-[(- 2.179 x 10-18-18 J)/n J)/n22lowlow]]

= - 2.179 x 10= - 2.179 x 10-18-18 J[(1/n J[(1/n22highhigh) - (1/n) - (1/n22

lowlow)])]Does this equation look familiar?Does this equation look familiar?

c = R[(1/mc = R[(1/m22) - (1/n) - (1/n22)])]

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ATOMIC STRUCTUREATOMIC STRUCTURENiels Bohr won the Nobel Prize for his work. However, the model only worked perfectly forhydrogen. What about all of those other elements??What about all of those other elements??

Louis de Broglie - Thought that if light, which wasthought to have wave characteristics, could also haveparticle characteristics, then perhaps electrons, whichwere thought to be particles, could have characteristicsof waves.

h/mvh/mv

An electron in an atom was a “standing wave”!An electron in an atom was a “standing wave”!

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Werner Heisenberg - Developed the “uncertainty”principle: It is impossible to make simultaneous andIt is impossible to make simultaneous andexact measurements of both the position (location)exact measurements of both the position (location)and the momentum of a sub-atomic particle such asand the momentum of a sub-atomic particle such asan electron.an electron.

((x)(x)(p) p) h/2 h/2

Our knowledge of the inner workings of atoms andmolecules must be based on probabilities ratherthan on absolute certainties.

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ATOMIC STRUCTUREATOMIC STRUCTUREErwin Schrödinger - Developed a form of quantummechanics known as “wave mechanics”.

HHEE

H = Hamiltonian operatorE = Total energy of the systemWave function

[(-h2)/(82m)]2 - [e2/r] = E

This is simply a quantum mechanical statement of the Lawof Conservation of Energy

Kinetic EnergyKinetic Energy TermTerm

Potential EnergyPotential Energy TermTerm

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ATOMIC STRUCTUREATOMIC STRUCTUREOf the numerous solutions to the Schrödinger equationfor hydrogen, only certain ones are allowed due to thefollowing boundary conditions:

, the wave function, must be continuous and finite. It must be single-valued at all points (There can’t betwo different probabilities of finding an electron at onepoint in space). The probability of finding the electron, 2, somewherein space must = 1.

- +

2dxdydz = 1

Y has many values that meet these conditions. They areY has many values that meet these conditions. They arecalled “orbitals”.called “orbitals”.

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ATOMIC STRUCTUREATOMIC STRUCTUREWave Function - A mathematical function associatedwith each possible state of an electron in an atom ormolecule.

It can be used to calculate the energy of anelectron in the state

the average and most probable distance from thenucleus

the probability of finding the electron in anyspecified region of space.

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ATOMIC STRUCTUREATOMIC STRUCTUREQuantum Numbers:

Principle Quantum Number, n - Principle Quantum Number, n - An integergreater than zero that represents the principleenergy level or “shell” that an electron occupies.

EnergyEnergy # of orbitals# of orbitalsnn LevelLevel ShellShell nn22

11 1st 1st K K 1122 2nd 2nd L L 2233 3rd 3rd M M 9944 4th 4th N N 16 16etc. etc. etc. etc.

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ATOMIC STRUCTUREATOMIC STRUCTUREAzimuthal Quantum Number, l - Azimuthal Quantum Number, l - The quantum number that designates the “subshell” an electronoccupies. It is an indicator of the shape of an orbitalin the subshell. It has integer values from 0 to n-10 to n-1.

l = 0, 1, 2, 3, …, n - 1l = 0, 1, 2, 3, …, n - 1

s p d fs p d f

Magnetic Quantum Number, mMagnetic Quantum Number, mll - - The quantum

number that determines the behavior of an electronin a magnetic field. It designates the the orbitalorbital andhas integer values from -l to +l including 0-l to +l including 0.

mmll = -l, …, -3, -2, -1, 0, +1, +2, +3, …, +l = -l, …, -3, -2, -1, 0, +1, +2, +3, …, +l

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ATOMIC STRUCTUREATOMIC STRUCTUREOrbitalOrbital # of# of

nn l Name ml Name mll Orbitals Orbitals

11 00 1s 1s 0 0 1 122 00 2s 2s 0 0 1 1 1 2p1 2p -1, 0, +1 -1, 0, +1 3 333 00 3s 3s 0 0 1 1 1 3p1 3p -1, 0, +1 -1, 0, +1 3 3

22 3d 3d -2, -1, 0, +1, +2 -2, -1, 0, +1, +2 5 5etc.etc. etc.etc. etc. etc. etc.etc. etc. etc.

Spin Quantum Number, mSpin Quantum Number, mss - - The quantum number

that designates the orientation of an electron in a magnetic field. It has half-integer values, +½ or -½.+½ or -½.

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ATOMIC STRUCTUREATOMIC STRUCTURESo what do atoms look like?So what do atoms look like?

A. Interpretation of : The probabilityprobability of findingan electron in a small volume of space centered around some point is proportional to the value ofat that point.

B. Electron Probability Density vs. r

C. Dot Density Representation: Imagine super-imposing millions of photographs taken of an electron in rapid succession.

D. Radial Densities

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Electron Configuration

A. Many-electron atom: An atom that containstwo or more electrons.

B. Problems with the Bohr model:

1. It “assumed” quantization of the energylevels in hydrogen.

2. It failed to describe or predict the spectraof more complicated atoms.


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C. What are the differences in electron energylevels in hydrogen vs. more complicated atoms?

1s

2s 2p

3s 3p 3d

Ground State Hydrogen AtomGround State Hydrogen Atom


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H

1s

2s 2p

Li

1s

2s2p

Splitting of the DegeneracySplitting of the Degeneracy


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1. In hydrogen, all subshells and orbitals in agiven principal energy level have the same energy.They are said to be DegenerateDegenerate.

2. In many-electron atoms, s-orbitals have lowerenergy than p-orbitals which have lower energythan d-orbitals which have lower energy than f-orbitals, etc., etc.

3. Reason: Complex electrostatic interactions.

Splitting of the DegeneracySplitting of the Degeneracy


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+-

Hydrogen ++

- -

Helium

+++

Lithium

- --

A. Shielding Effect - A decrease in the nuclear forceof attraction for an electron caused by the presenceof other electrons in underlying orbitals.

B. Effective Nuclear Charge - A positive chargethat may be less than the atomic number. It is thecharge “felt” by outer electrons due to shielding byelectrons in underlying orbitals.

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The Pauli Exclusion Principle - No two electron inNo two electron inthe same atom can have the same four quantumthe same atom can have the same four quantumnumbers.numbers.

H + e- H -

QuantumQuantum Electron 1Electron 1 Electron 2Electron 2NumberNumber nn 11 11 ll 00 00

mmll 00 00

mmss +1/2 +1/2 -1/2 -1/2


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The Aufbau Principle - A procedure for “building up”the electronic configuration of many-electron atomswherein each electron is added consecutively to thelowest energy orbital available, taking into accountthe Pauli exclusion principle.

Order of Filling - 1s1s 2s2s 2p2p 3s3s 3p3p 4s4s 3d3d 4p4p 5s5s

Increasing Energy1s2s 2p3s 3p 3d4s 4p 4d 4f5s 5p 5d 5f 5g

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Designating Electron Configurations -

Standard DesignationStandard Designation

HH 1s1s11

HeHe 1s1s22

LiLi 1s1s22 2s 2s11

BeBe 1s1s22 2s 2s22

B 1s1s22 2s 2s2 2 2p2p11

C C 1s1s22 2s 2s2 2 2p2p22 Orbital Diagram DesignationOrbital Diagram Designation

H

He

1s

1sLi

Be

1s

1s 2s

2s

B

C1s

1s

2s

2s 2p

2p

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Core Designation - Core Designation - A designation of electronicconfiguration wherein the outer shell electronsare shown along with the “core” configuration of the closest previous noble gas.

Li

Na

K

Rb

Be

Mg

Ca

Sr

[He] 2s1

[Ne] 3s1

[Ar] 4s1

[Kr] 5s1

[He] 2s2

[Ne] 3s2

[Ar] 4s2

[Kr] 5s2

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Hund’s Rule of Maximum Multiplicity - Electronsoccupy a given subshell singly and with parallel spinsuntil each orbital in the subshell has one electron.

““Electrons try to stay as far apart as possible”Electrons try to stay as far apart as possible”

Elevator Analogy Bus Seat Analogy

B

C

N

[He] 2s2 2p1 [He]

[He] 2s2 2p2

[He] 2s2 2p3

[He]

[He]

2s 2p

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Assignment: Assignment: Write the electron configuration usingWrite the electron configuration usingall three types of designation for lead (Pb).all three types of designation for lead (Pb).

Electronic Configuration for postive ions (cations) -Cations are formed by removing electrons in orderof decreasing nn value. Electrons with the same nnvalue are removed in order of decreasing ll value.

Pb [Xe] 6sPb [Xe] 6s22 4f 4f1414 5d 5d1010 6p 6p22

Pb 1sPb 1s22 2s 2s22 2p 2p66 3s 3s22 3p 3p66 4s 4s22 3d 3d1010 4p 4p66 5s 5s22 4d 4d1010 5p 5p66 6s 6s22

4f4f1414 5d 5d1010 6p 6p22

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Assignment: Assignment: What are the electron configurations forWhat are the electron configurations for

FeFe2+2+ FeFe3+3+ CrCr CrCr3+3+ SeSe2- 2- ? ?

Questions?Questions?

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Chemistry 4362