Chemistry 64 Winter 2006GENERAL INFORMATION AND SYLLABUS

Instructor: David Glueck (305 Burke) 6-1568Office Hours: Monday 1-3; Wednesday, 2-3, or by appointment.

Texts: "Inorganic Chemistry, 3rd edition," Shriver + Atkins. "Guide to Solutions for InorganicChemistry," Strauss, 3rd edition (& Other Reserve Reading). Note: the primaryresource will be the lecture notes (handouts).

Lectures: M,W,F 8:45–9:50 AM, 007 Steele.X-hour: Th 9:00–9:50 AM, 007 Steele: We will use this period frequently.

30 lectures are scheduled (see below).Laboratory: Th/Fr 2-6 PM, 306 Steele. NOTE -- graduate students do not need to dothe lab experiments, but they are responsible for this material on the exams. There will bea mandatory lab lecture on 1/12 in the x-hour slot. Labs will begin Thursday 1/12.WEB: www.dartmouth.edu/~chem64/. Some of the course material will be at this site.__________________________________________________________________

APPROXIMATE LECTURE SCHEDULEWeek Dates Topics Chapter/Sections__________________________________________________________________

1 1/4, 1/5,* 1/6 Overview; Molecular Structure, Symmetry,Point Groups 3.1-3.3, 4.1-4.4

2 1/9,1/11,1/12,*1/13 Character Tables, Vibrational Spectroscopy 4.5-4.6, 4.8-4.9

1-12* = LAB LECTURE. YOU MUST ATTEND

3† 1/18, 1/19,*1/20 Orbital Symmetry, MO Theory of Diatomics,MO Theory of Polyatomics, Walsh Diagrams 1.3-1.8, 4.7, 3.4-3.13

EXAM #1: TUESDAY, JANUARY 24, 7:30–9:30 PM Wilder 104

4 1/23, 1/25, 1/27 Lewis Acids & Bases, Hardness & Softness 5 (esp. 5.1-5.3, 5.7-5.14)

5 1/30, 2/1, 2/3 Transition Metal Coordination ChemistryStructures, Isomers & Nomenclature 7.1–7.3

6† † 2/6, 2/8, 2/9* Ligand Field Theory, Magnetism, MO Theory 7.4–7.7

7 2/13, 2/15, 2/17 Electronic Spectra of Transition Metal Complexes 13.1–13.5

EXAM #2: TUESDAY, FEBRUARY 21, 7:30–9:30 PM Wilder 104

8 2/20, 2/22, 2/24 Ligand Substitution, Mechanisms of 7.8, 14.1–14.10Electron Transfer Reactions 14.12-14.13

9 2/27, 3/1, 3/3 Complexes of π-Acceptor Ligands 16.1–16.7

CO, Olefins, and the 18-Electron Rule

10 3/6, 3/8 Organometallic Chemistry

FINAL EXAM (Monday, March 13, 11:30 AM)Location TBA

__________________________________________________________________ * Planned X-Hour Class. Other X-Hour Classes may be held.† No class held on Monday, January 17, Martin Luther King Day. †† No class on Winter Carnival Holiday Friday, Feb. 10; no lab this week.

________________________________________________________________

Grading Point Distributions: Laboratory 100Exams 1 100

2 100Final Exam 100TOTAL 400

Failing the laboratory will automatically result in failure of the entire course.__________________________________________________________________

Students with Disabilities: I encourage students with disabilities, including "invisible"disabilities like chronic diseases and learning disabilities, to discuss with me after class or duringoffice hours any appropriate accommodations which might be helpful to them.

__________________________________________________________________________

HONOR PRINCIPLE: It is important to be explicit in stating how the broad principle ofacademic honor applies in this course. Please feel free to inquire further if the statementsbelow are not adequate.

1. Examinations . Any of the numerous activities normally considered cheating are violations.Examinations are not proctored; however, it will probably be necessary for me to be present from time to timeduring the exam to answer questions which arise.

Since the exam graders do not claim to have perfect records of accuracy, claims of injustice in grading willbe carefully considered. The changing of an answer followed by the return of the paper to the instructor forreconsideration is a direct violation of the Honor Principle.

2. Laboratory . The principle of academic honor is at the very heart of experimental science. Thefollowing remarks apply to the laboratory work in Chemistry 64:

Unless permission is granted by the instructor, use of another student's laboratory data is a violation. Whenuse of another's data is allowed, the source of the data must be indicated. Fabrication of data or alteration of yourown data to secure some desired result is also a violation. In the case of experiments where two students worktogether and data have been recorded in one student's notebook, a copy of the data may be made in the other student'snotebook with an appropriate citation to the location of the original data. Any other material in the notebook whichhas been copied from any source whatever must also be provided with a source citation. The laboratory report mustrepresent your independent calculations and individual conclusions although comparison of numerical resultswith another student is permitted. Of course, direct copying of any portion of another student's laboratory report is aclear violation of the Honor Principle.

3. Problem Assignments . Homework is excluded from Honor Principle constraints. However,students are strongly encouraged to tackle each problem set independently until the point is reached where furthertime and effort seem futile. At that point, collaboration with one's fellow students is encouraged.__________________________________________________________________

MOLECULAR MODELS: You will need a set of molecular models containing atoms withcoordination number greater than 4. Buy them at the bookstore, or online athttp://vig.prenhall.com:8081/catalog/academic/product/0,1144,0139554440-FEA,00.html. Be sure toget them before the first lab (1/12 or 1/13)!

LABORATORY MANUAL: Separate handout. Lab notebooks will be provided. Lab lecture1/12; first lab is Thursday 1/12 or Friday 1/13.

LABORATORY: The laboratory portion of this course will introduce you to techniques andspectroscopic methods employed by Inorganic Chemists to synthesize and characterize molecules.Of course many of these techniques and methods can also be applied to the synthesis andcharacterization of organic molecules.

FURTHER DETAILS ON THE LAB PORTION OF THIS COURSE ARE PROVIDEDON A SEPARATE HANDOUT

__________________________________________________________________

ADVERTISEMENTMORE INORGANIC CHEMISTRY!

Want to see more inorganic chemistry, with applications?

Take some or all of these cross-listed undergraduate/graduate classes, offeredin the spring and fall terms:

CHEM 90/130: Organometallic Chemistry (Spring 2007, Hughes)CHEM 91/131: Catalysis (Fall 2007, Glueck)CHEM 92/132: Bio-Inorganic Chemistry (Spring 2006, Wilcox)

• Small class sizes (5 in Chem 91/131 fall 2005)• No lab.

Chem 64 Reserve Reading List

Note: For almost all of this course, you will not need to look at any of these books (besidesthe textbook and the solutions manual.) Some may be helpful in giving a differentviewpoint or more details. The encyclopedic Cotton+Wilkinson text is usually a goodplace to start, and is often useful for the lab.

http://libcat.dartmouth.edu/search/rchem/rchem/1%2C5%2C5%2CB/frameset&FF=rchem+064+w05&1%2C1%2C

Title Copies Library Call Number(Alphabetically) (Specify edition, please) Needed (If owned by Library)

Cotton & Wilkinson Advanced Inorganic Chemistry 6th 1 QD 151.2 .C68 1999Cotton, Wilkinson & Gaus Basic Inorganic Chemistry 6th 1 QD 151.2 .C69 1999Douglas, McDaniel & Alexander Concepts & Models of Inorganic Chem. 3rd 1 QD 475 .D65 1999

Huheey Inorganic Chemistry 3rd 1 QD 151.2 .H84 1983Purcell & Kotz Inorganic Chemistry 1 QD 151.2 .P87

Cotton Chemical Applications of Group Theory 3rd 1 QD 461 .C65 1990Vincent Molecular Symmetry & Group

Theory1 QD 461 .V52

Kettle Symmetry & Structure 2n d 1 QD 471 .K47516 1995Karplus & Porter Atoms & Molecules 1 QD 461 .K33

Ballhausen & Gray Molecular Orbital Theory 1 QD 461 .B24Ballhausen Introduction to Ligand Field Theory 1 QD471 .B3

Figgis Introduction to Ligand Fields 1 QD 475 .F57Drago Physical Methods for Chemists 2nd 1 QD 453.2 .D7 1992

Nakamoto Infrared and Raman Spectra of 1 QD 96 .I5N33 1997 v.1, v.2Inorganic and Coordination Compounds 5th

Basolo & Pearson Mechanisms of Inorganic Reactions2n d

1 QD 171 .B32 1967

Langford & Gray Ligand Substitution Processes 1 QD 471 .L23Wilkins The Study of Kinetics & Mechanisms 1 QD 474 .W54

of Reactions of Transition Metal ComplexesAngelici Synthesis & Techniques in 1 QD 155 .A53 1977

Inorganic Chemistry 2n d

Jolly The Synthesis & Characterization of 1 QD 156 .J65Inorganic Compounds

Shriver, Atkins Inorganic Chemistry, 3rd Edn. 1Strauss Solutions to Inorg. Chem. 1

Chemistry 64 Lab Winter 2006

GENERAL INFORMATION

Instructor: David Glueck (305 Burke)

Teaching Assistants: Brian Anderson (318 Burke)Jian Yuan (310 Burke)

Time: Thursday or Friday, 2:00-6:00 PM, 306 Steele

Laboratory Notebook: this will be issued when you check into the lab (do not purchaseone at the bookstore).

Schedule: Your lab manual contains six experiments (see the brief descriptions on thenext page). Each laboratory period will begin with some comments in the laboratoryabout the experiment; please do not be late for the start of lab. Experiment 1 is a"dry lab" and will require no lab report.

Lab reports for the remaining experiments will be duewithin one week of your lab section. (Thus, if you have lab on ThursdayJanuary 17, your report is due on Thursday January 24). You can turn in reports to theTA's or to me. Please don't pester the TA's with questions about the lab reports; ask meinstead.

There will be a penalty for late laboratory reports!• one or two days late -- 20% penalty. Example: you're 2 days late and get a score of

8 out of 10. After deducting 20% your corrected score is 6.4 out of 10.• 3 to 6 days late -- 40% penalty. Example: you're 5 days late and get a score of 6

out of 10. After deducting 40% your corrected score is 3.6 out of 10.• more than 6 days late -- 60% penalty. Example, you're 2 weeks late and get a

score of 4 out of 10. After deducting 60% your corrected score is 1.6 out of 10.

Because of possible delays between doing the experiment and writing up the labreport, accurate and complete observations in your notebook are crucial. This isespecially important since part of your lab grade (see below) will be based on evaluationof your notebook.

Fees: The standard laboratory charge, which includes the cost of nonreturnable itemsand the laboratory notebook, is $16.00. Further, additional charges will be made forbreakage, and/or excessive damage and the total sum will be added to your College billat the end of the term. Please take good care of your equipment--it is expensive.

Grading: Your lab grade is based on:

Reports 70%Notebooks 20%Instructor's Evaluation ofTechnique and Comprehension 10%

The laboratory portion of the course will count for about 25%of the final grade.However, failure to complete the laboratory (this includesturning in the lab reports!) will result in a failing grade.

LABORATORY EXPERIMENTS

1. Molecular Structure and Symmetry (1/12 - 1/13): Apply VSEPR to build models of

molecules and assign them to their molecular symmetry groups (point groups).

2. Spectra and Structure of Nitrile Complexes (1/19 - 1/20): Prepare a copper

acetonitrile complex and a palladium benzonitrile complex. Use IR and NMR spectra

to determine their structures.

3. Synthesis and Resolution of a Chiral Nickel Complex (1/26 - 1/27): Prepare and

separate a racemic mixture of Ni-phenanthroline complexes. Study the chiroptical

properties of one enantiomer of the Ni complex.

4. Four-Coordinate Nickel Diphosphine Complexes (2/2 - 2/3): Prepare two closely

related diphosphine complexes of nickel dichloride, and compare their physical and

spectroscopic properties.

5. No lab this week, Winter Carnival holiday Friday 2/10!

6. Stabilization of Chromium(II) by Complexation (2/16 - 2/17): Use inert atmosphere

techniques to prepare air sensitive solutions of Cr(II). Stabilize this oxidation state by

ligand coordination and make a compound with a metal-metal multiple bond.

7. Preparation of Chromium(III) Compounds: the Spectrochemical Series (2/23 -

2/24): Prepare Cr(III) compounds by three different procedures, in one case using

liquid ammonia, and study their electronic properties that lead to their distinctive

colors spectroscopically.

ACADEMIC HONOR PRINCIPLEThe principle of academic honesty is at the very heart of experimental

science. The following remarks apply to the laboratory work in Chemistry 64:

• Unless permission is granted by the instructor, use of another student'slaboratory data is a violation.

• When use of another's data is allowed, the source of the data must be indicated.

• Fabrication of data or alteration of your own data to secure some desired resultis also a violation. [This happened in Winter 2001 and resulted in a 1-termsuspension.]

• In the case of experiments where two students work together and data havebeen recorded in one student's notebook, a copy of the data may be made in theother student's notebook with an appropriate citation to the location of theoriginal data. Any other material in the notebook which has been copied from anysource whatever must also be provided with a source citation.

• The laboratory report must represent your independent calculations andindividual conclusions, although comparison of numerical results with anotherstudent is permitted, with appropriate attribution.

• Of course, direct copying of any portion of another student's laboratory report isa clear violation of the Honor Principle.

Any violation of the Honor Principle in this course will result in notification of theCollege Committee on Standards.

If you have ANY QUESTIONS about how the Honor Principle applies to anysituation in this course, PLEASE DO NOT HESITATE TO CONTACT YOURINSTRUCTOR.

LABORATORY SAFETY

1. Wear safety goggles in the lab. Repeated violation of this rule will lead to ejectionfrom the lab.

2. Never use an open flame in the lab.

3. Smoking, eating, and drinking is absolutely forbidden in this laboratory.

4. Never bring coats or bulky flammable items into the laboratory.

5. Know the location of the nearest fire extinguisher, safety shower, eye wash fountain,and exit.

6. Do all pipetting with a suction bulb. Mouth pipetting is absolutely forbidden.

7. When a reaction is left alone for extended periods of time (>1/2 hour), leave a notenext to it indicating important facts for persons working in that vicinity.

8. Know the physical, chemical, physiological properties (as far as possible) of thereactants, products, and solvents used in each preparation. Be ready for questionsabout the toxicity of the materials which you will be using.

9. Do all manipulations in the hood unless directed otherwise.

10.Know and follow the proper disposal method for chemicals.

11.Clean up your work area in the laboratory before you leave.

12.Wash your hands thoroughly before leaving the lab.

13. If you have any questions or doubts about the experimental procedures, contact theinstructor or the teaching assistants before beginning experimental work.

LABORATORY GUIDELINES

1. Safety glasses must be worn by everyone who enters the lab.

2. No sandals or shorts are to be worn while in the lab.

3. Do the experiments in the hood.

4. Cleanliness of the laboratory is the responsibility of the students who use it and theTeaching Assistants who supervise them.

At the conclusion of each lab session: - All glassware must be cleaned and put in the lockers. Do not put dirty glasswarein the lockers.

- Benchtops are to be cleaned of any spills and chemical residue.- Balances and the areas around them are to be free of spilled chemicals and used

weighing paper.- Reagent dispensing areas are to be free of spilled chemicals or liquid reagents.- Hoods are to be clean and emptied of all glassware and chemicals.

The TAs will inspect your lab station and associated commonequipment areas before signing your lab notebook. They willalso provide brief qualitative assessment of your notebookand lab technique each week.

6. Place all broken glassware in the SHARPS containers. Do not put broken glass inthe trash.

7. Dispose of waste chemicals in the containers provided. Do not put waste chemicalsor products in the lockers.

8. Report any broken glassware to the TA for replacement.

LABORATORY REPORTSIn the laboratory, record all pertinent observations and data for each experiment in a

neat, concise fashion in pen in your notebook as you do the experiment. Writing upa prelab as done in other courses is also useful. Notebooks may be collected, andexamined, without notice, at various times during the term; evaluation of your notebookcounts as part of your lab grade.

Here is the format for the lab reports, which should be BRIEF but clearly written.1. TITLE & DATE: The title of the experiment and the date it was done should be listedon the front page along with the name(s) of your lab partners.2. INTRODUCTION: (BRIEF!) Background material explaining why you are performingthe experiment. Information for this section can be found in the lab handout and/or inthe references given at the beginning of each experiment.3. RESULTS & DISCUSSION: What happened and how you interpret it. Information toinclude here: what compounds you made, their spectral data, answers to the questionsfrom the lab manual, and discussion of the results. If you use an idea from a referenceto help you answer a question, the reference should be footnoted (include thereferences as endnotes at the end of the report).4. EXPERIMENTAL: Each new complex isolated should be listed separately. A goodformat is:

Complex aa: A sample of $$ [X g, Y mol] was dissolved in H2O (30 mL) to afford agreen solution which was then added to a blue solution of ## [X g, Y mol] in MeOH (10mL). The solution was stirred at room temperature for one hour. Filtration of theresulting purple precipitate and subsequent washing with H2O (3 x l 5 mL) yielded,before recrystallization, purple crystals of @@ (X g, Y mol, % yield), m.p. 102-104 °C.5. CONCLUSION: This can be brief, but you need to summarize the results.6. REFERENCES: Use the standard American Chemical Society format:

(1) Huheey, J. E. Inorganic Chemistry: Principles of Structure and Reactivity, 2ndEd.; Harper & Row, New York, 1978, 498-507.

(2) Schlafer, H. L. J. Phys. Chem. 1965, 69, 2201-2208.All lab reports MUST be printed or typed (handwritten reports will not be accepted).

Spectra should be stapled to the last page or pasted into the report itself.

1

Chemistry 64

REVIEW TOPICS

Just as you need to know the alphabet in order to spell words in the Englishlanguage, I also expect you to know from memory the names and symbols of thefirst 86 elements of the Periodic Table. These are the component parts from whichalmost all known materials are made. The Periodic Table is your guide to the chemistry ofthe elements and their compounds. You should know your way around it, and be able t ocalculate quickly the valence electron configuration of any element in anyoxidation state.

I will expect you to be familiar with the following terms, concepts and topics fromyour General Chemistry and Organic Chemistry courses. Some of these topics arereviewed in your text, primarily in Chapters 1 and 2, and in some class handouts. You mayneed to go back to your General Chemistry text to freshen up on other subjects.

IF YOU HAVE ANY PROBLEMS WITH THIS MATERIAL, COME AND ASK FOR HELP!!

A. General Chemistry (Chem 3/5 and Chem 6, or Chem 10)

Atomic orbitals: s, p, dmathematical description and spatial visualization(you should be able to draw them correctly from various perspectives)angular portion (shape) & radial portion (size and penetration)core and valence orbitalschange of phase of wavefunction in different orbital lobes - nodal characteristicsenergies in hydrogen atom and in multielectron atoms and ions

Periodic table and periodic trendselectronic configuration, Aufbau Principle, Hund's Rulesymbols and names of the elementsmain group, transition metals, lanthanides, actinidesionization potential and electron affinity - electronegativitypolarizability

Thermodynamicsenthalpy (H); enthalpy-driven reactionentropy (S); entropy-driven reactionfree energy (G) and its relation to H and Sequilibrium constant (K) and its relation to ∆G˚°redox potential (E°) and its relation to ∆G˚

Kineticsrate expressions for 1st and 2nd order reactions - mechanistic implicationsactivation energy; Arrhenius equation, rate determining stepcatalysis, effect of catalyst on equilibrium constants and rate constantsreaction coordinate; free energy reaction profile

2

Valence Electron Bonding Theory (coordinate covalent 2-e– bonds)octet rule, and exceptions to itValence Shell Electron Pair Repulsion Theory (VSEPR)hybridization - hybrid atomic orbitalsresonance forms - evaluation of their relative importanceisoelectronic atoms ions and moleculesLewis Base (e-pair donor) and Acid (e-pair acceptor)bond lengths and bond strengthsbond polarity - molecular dipoles

Molecular Orbital Theoryhomonuclear diatomic M.O. energy level diagramsbonding, nonbonding, and antibonding molecular orbitalscalculation of bond orderσ-bonds - nodal characteristicsπ-bonds - nodal characteristicsδ-bonds - nodal characteristics [new; to be introduced soon]

B. Organic Chemistry (Chem 51-52, or 57-58)

nomenclaturenucleophile (Lewis Base); SN1 and SN2 mechanismselectrophile (Lewis Acid)IR spectroscopy

identification of functional groupstransitions between vibrational states

UV spectroscopytransitions of electrons from ground state to excited electronic states

Mass Spectrometryparent (molecular) ion; fragmentation patterns

Nuclear Magnetic Resonance Spectrometrychemical shift (δ); units ppmspin-spin coupling; coupling constants (J); units Hzmagnetic equivalence; symmetrical equivalencedynamics

conformational exchangechemical exchange

I= 1/2 nuclei 1H, 1 3C: & 1 9F, 3 1P, 1 0 3Rh, 1 1 3Cd, 1 9 5Pt, etc.

C. Important Termsligand - atom, ion or molecule bonded to a metaloxidation state - formal charge on a metal iondn configuration - number of valence d electronscoordination number - number of ligands directly bound to a metalfirst (inner) coordination shell - set of ligands bound directly to a metalsecond (outer) coordination shell - solvent or counter ions not directly bound tothe metalelectronic structure - the spatial and nodal character, electron population andenergies of the orbitals (usually only the valence orbitals are considered) of an atom,ion or molecule

1

Chem 64 PROBLEM SET #1 – REVIEW1. State the unique set of three quantum numbers which characterize each of the following

hydrogen atom atomic orbitals: 1s, 2s, 2p, 3d, 4d, 4f.

2. What does the term penetration mean in the atomic orbital context, and why is itimportant in understanding the relative energies of s, p, d, and f electrons having thesame principal quantum number?

3. On the modern periodic table below indicate the: alkali metals, actinides, alkaline earthmetals, halogens, noble gases, main group elements, d-block elements, f-blockelements, lanthanides, transition elements.

H1.0079

1He

4.00260

2

Be9.01218

4Li6.941

3B10.81

5C

12.011

6N

14.0067

7F

18.9984

9Ne

20.179

10

24.305

12Mg

22.9898

11Na

26.9815

13Al

28.0855

14Si

30.9738

15P

35.453

17Cl

39.948

18Ar

40.08

20Ca

39.0983

19K

44.9559

21Sc

47.88

22Ti

50.9415

23V

51.996

24Cr

54.9380

25Mn

55.847

26Fe

58.9332

27Co

58.69

28Ni

63.546

29Cu

65.39

30Zn

69.72

31Ga

72.59

32Ge

74.9216

33As

78.96

34Se

79.904

35Br

83.80

36Kr

87.62

38Sr

85.4678

37Rb

88.9059

39Y

91.224

40Zr

92.9064

41Nb

95.94

42Mo

(98)

43Tc

101.07

44Ru

102.906

45Rh

106.42

46Pd

107.868

47Ag

112.41

48Cd

114.82

49In

118.71

50Sn

121.75

51Sb

127.60

52Te

126.905

53I

131.29

54Xe

137.33

56Ba

132.905

55Cs

138.906

57La

178.49

72Hf

183.85

74W

186.207

75Re

190.2

76Os

192.22

77Ir

195.08

78Pt

196.967

79Au

200.59

80Hg

204.383

81Tl

207.2

82Pb

208.980

83Bi

(209)

84Po

(210)

85At

(222)

86Rn

226.025

88Ra

(223)

87Fr

227.028

89Ac

(261)

104Unq

(262)

105Unp

(263)

106Unh

(262)

107Uns

(265)

108Uno

(266)

109Une

O

180.948

8

16

73

S

Ta

174.967173.04168.934167.26164.930162.50158.925157.25151.96150.36(145)144.24140.908

(260)(259)(258)(257)(252)(251)(247)(247)(243)(244)(237)238.029231.036232.038

90 91 92 93 94 95 96 97 98 99 100 101 102 103140.12Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho

Th Pa U Np Pu Am Cm Bk Cf Es

Er Tm Yb Lu

Fm Md No Lr

15.9994

32.06

58 59 60 61 62 63 64 65 66 67 68 69 70 71

Practice filling in the symbols (and names) for the elements from memory. I expectyou to memorize the names and symbols of the elements 1–86. See thew e b - s i t e f o r a u s e f u l l i n k t o p r a c t i c e this:www.dartmouth.edu/~chem64/reviewps1.html.

4. State the electronic configuration and the number of unpaired electrons for each of thefollowing gas phase ions: K+, Ti3+, Cr3+, Fe2+, Cu2+, S b3+, Se2–, Sn4+, Ce4+,Eu2+, Lu3+

5. The heavier atoms in any given group in the periodic table have larger inner cores,which lower the ionization potential of their valence electrons, but generally increasetheir polarizability. What influence does this pattern have on their boiling points?

6. On the basis of electronegativities, state which member of each pair is the more polarbond, and indicate the direction of the dipole. [Try to estimate relativeelectronegativities, and look up the numbers if needed.]

C–N or N–O P–S or S–Cl Sn–I or C–I

2

7. Define the terms exothermic and endothermic for a physical or chemical process.What are the signs of ∆H for each?

8. For a chemical reaction, what would be the significance of ∆G° < 0, ∆G° = 0, and ∆G°> 0? What magnitude of the equilibrium constant (K) is associated with each case?

9. What is the conventional, arbitrary assumption made in defining the magnitudes of half-cell potentials (E°)? What is the convention for their signs?

10. The N–N bond energy in F2N–NF2 is only about 80 kJ mol–1 compared to 160 kJmol–1 in H2N–NH2 . Suggest a reason for this.

11. Some chemical reactions have two-term kinetic rate laws, for example:[Pt(NH3)3Cl]– + Br– –––> [Pt(NH3)3Br]– + Cl–Rate = k1 [Pt(NH3)3Cl]– + k2 [Pt(NH3)3Cl]–[Br]–

What does such a rate law imply about the reaction mechanism(s)?

12. Define the term isoelectronic and give examples for main group molecules and ions,and transition metal ions.

13. Use the Valence Shell Electron Pair Repulsion (VSEPR) Theory to predict the stablestructures for: PCl2F3, PCl2Me3, and SF4. In all cases the central atom is listed first andall other atoms are directly bound to it.

[Note: Although it is not covered in our standard introduction to VSEPR (as in Chem 6), themore electronegative group is often found in the axial position in trigonal bipyramidalstructures like PCl2F3 and PCl2Me3. Several “explanations” of this observation,including hybridization and MO approaches, have been worked out, but we won’tcover them in this course.]

Describe the "ideal" central atom hybrids for each electron pair; any bond angle deviationsfrom the ideal structure; and which molecules have non-zero dipole moments.

For each of the latter, identify the symmetry axis along which lies the molecular dipole.

14. Use VSEPR to predict the structures of the following molecules and ions.Indicate any deviations of bond angles from the ideal values.BeF2 CH2 (singlet [no unpaired electrons]) OF2 PCl4+

SO2 ClF2+ BrF3 BrF5 SbF5 ICl4–

15. Predict the structure of HCP (C is the central atom) using VSEPR theory.

16. Using the 2s and 2p atomic orbitals as a basis set, prepare a "generic" molecularorbital (M.O.) energy level diagram for a homonuclear diatomic molecule. Use thisdiagram to predict the relative bond strengths and the numbers of unpaired electronsfor the series of diatomics O2+, O2, O2–, and O22–.

17. from Shriver + Atkins: Chapter 1 Exercises 9-11, 13, 16, 18, Problem 1.3;Chapter 3 Exercises 1-2, 4-7, 9, 10, Problem 1

1

Chem 64Solutions to Problem Set #1, REVIEW

1. AO n l m1s 1 0 02s 2 0 02p 2 1 –1,0,13d 3 2 –2,–1,0,1,24d 4 2 –2,–1,0,1,24f 4 3 –3,–2,–1,0,1,2,3

2. Penetration relates to the radial probability distribution of electron density inan atomic orbital, and the percentage of this distribution which is close to the nucleusand consequently feels a larger nuclear charge. Electrons in 3d orbitals are shieldedfrom the full nuclear charge by core electrons (1s,2s,2p) while 3s and 3p electronshave larger fractions of their electron density which penetrate the core and feel thenuclear charge. Thus, electrons in these latter orbitals are more stable (lower energy)than those in the 3d orbitals.

3. alkali metals: Li column; actinides: from Ac (Z=89) through No (Z=102); alkalineearth metals: Be column; halogens: F column; noble gases: He column; main groupelements: B through He columns; d-block elements (aka transition metals): Scthrough Zn columns, except not Y, La, or the 4th-row elements; f-block elements:those exceptions plus the elements in the part below the main table; lanthanides: Lathrough Lu.

H1.0079

1He

4.00260

2

Be9.01218

4Li6.941

3B10.81

5C

12.011

6N

14.0067

7F

18.9984

9Ne

20.179

10

24.305

12Mg

22.9898

11Na

26.9815

13Al

28.0855

14Si

30.9738

15P

35.453

17Cl

39.948

18Ar

40.08

20Ca

39.0983

19K

44.9559

21Sc

47.88

22Ti

50.9415

23V

51.996

24Cr

54.9380

25Mn

55.847

26Fe

58.9332

27Co

58.69

28Ni

63.546

29Cu

65.39

30Zn

69.72

31Ga

72.59

32Ge

74.9216

33As

78.96

34Se

79.904

35Br

83.80

36Kr

87.62

38Sr

85.4678

37Rb

88.9059

39Y

91.224

40Zr

92.9064

41Nb

95.94

42Mo

(98)

43Tc

101.07

44Ru

102.906

45Rh

106.42

46Pd

107.868

47Ag

112.41

48Cd

114.82

49In

118.71

50Sn

121.75

51Sb

127.60

52Te

126.905

53I

131.29

54Xe

137.33

56Ba

132.905

55Cs

138.906

57La

178.49

72Hf

183.85

74W

186.207

75Re

190.2

76Os

192.22

77Ir

195.08

78Pt

196.967

79Au

200.59

80Hg

204.383

81Tl

207.2

82Pb

208.980

83Bi

(209)

84Po

(210)

85At

(222)

86Rn

226.025

88Ra

(223)

87Fr

227.028

89Ac

(261)

104Unq

(262)

105Unp

(263)

106Unh

(262)

107Uns

(265)

108Uno

(266)

109Une

O

180.948

8

16

73

S

Ta

174.967173.04168.934167.26164.930162.50158.925157.25151.96150.36(145)144.24140.908

(260)(259)(258)(257)(252)(251)(247)(247)(243)(244)(237)238.029231.036232.038

90 91 92 93 94 95 96 97 98 99 100 101 102 103140.12Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho

Th Pa U Np Pu Am Cm Bk Cf Es

Er Tm Yb Lu

Fm Md No Lr

15.9994

32.06

58 59 60 61 62 63 64 65 66 67 68 69 70 71

4. In forming ions, atoms will lose electrons from levels of highest principal quantumnumber, n; with levels of equal n, the electron will be lost from the orbital of highest l.Electrons in degenerate orbitals will occupy orbitals singly to the maximum

2

permissible extent (Hund's rule of maximum multiplicity). These considerations leadto the following answers:

Configuration # unpaired electrons

K+(Ar) 0Ti3+(Ar)3d1 1Cr3+(Ar)3d3 3Fe2+(Ar)3d6 4Cu2+(Ar)3d9 1S b3+(Kr)4d105s2 0Se2–(Ar)3d104s24p6 0Sn4+ (Kr)4d10 0Ce4+(Xe) 0Eu2+(Xe)4f7 7Lu3+(Xe)4f14 0

Note: for the transition elements (Z≥21) the energy of the (n–1)d level usually liesslightly below that of the ns level. Consequently ionization of the s electrons occursbefore the d electrons. For lanthanoid and actinoid elements the f-level is the lowest-lying valence level. Thus transition metal ions always have a configuration [inert gas] ndm and f-blockelement ions always have [inert gas] nfm.

5. Increased polarizability leads to larger van der Waals forces (attractiveinteractions) between the atoms, and thus to a higher boiling point.

6. These are written with the more electronegative element 2nd, so the dipole(point positive charge) points that way.CN > NOS-Cl > P-SSn-I > C-I

7. Exothermic: giving off heat, ΔH < 0Endothermic: taking up heat from the surroundings, ΔH > 0

8. ΔGo = –RTlnKΔGo < 0 : reaction proceeds forward spontaneously to equilibrium: K > 1ΔGo = 0: reaction has no thermodynamic driving force: K = 1ΔGo > 0: reaction proceeds backward spontaneously to equilibrium: K < 1

3

9. One half-cell is chosen as a reference and its Eo is set at 0.000V; all others arereferenced to it. Typically the standard reference is the standard hydrogen electrode:Pt/H2(1 atm)/H+(1M)The half-cell potential (or full cell potential) is related to ΔGo by

ΔGo = –nFEo (n = # of electrons transferred; F = 1 faraday). Therefore,

a +Eo ensures a –ΔGo and a spontaneous forward reactiona –Eo ensures a +ΔGo and a spontaneous reverse reaction

Half-cell reactions are written as reductions, thus the more positive the valueof Eo, the more easily the reactant is reduced.

10. Two arguments can be used, both of which lead to the same conclusion: first,the lone pairs on F atoms attached to one N atom will repel those on F atoms on theadjacent N, serving to destabilize (and weaken) the N-N bond (relative to H2N-NH2); second, the strong electron-withdrawing F atoms will withdraw electron-densityfrom N leading to a weaker N-N bond.

[Both these arguments affect the relative energies of the reactant side of the equationfor dissociation of the N-N bond:

R2N-NR2 -----> 2 R2N. R = H or F

You should also think about how H and F would affect the relative stabilities of theproducts of this dissociation, since both sides will affect the magnitude of ΔHreaction].

11. The reaction is a nucleophilic substitution of Cl– by Br–, occurring at a Pt atom. A2-term rate law implies that 2 different mechanisms are operating: the first has arate constant k1 and its rate is (apparently) dependent only on [Pt(NH3)3Cl]–; the 2ndhas a rate constant k2 and its rate is dependent on both [Pt(NH3)3Cl]– and [Br–].Depending on the magnitudes of k1 and k2 one path may dominate or both maycontribute significantly to the overall observed reaction rate.[You probably haven’t seen this before, but that’s OK; we will discuss this type ofreaction and rate law in more detail later in the term.]

12. Atoms, ions or molecules are isoelectronic if they contain the same number ofelectrons:e.g. Ti3+ and V4+, CO and NO+This strict definition is frequently loosened to allow 'isoelectronic' to include only thevalence electrons of the atoms or ions.e.g. XeF4 and ICl4–, Co3+ and Pt4+.

4

13.

F PCl

Cl

F

F

SF

F

F

F

:

dsp3

dipole axis

>120°

more electronegative group axial

<90° > 90°

<120°

lone pair equatorial

dipole axisMe P

Me

Me

Cl

Cl

dsp3

no dipole momentno deviations from ideal geometry

Note: for trigonal bipyramidal structures like this, the more electronegative group isoften found in the axial position. Several “explanations” of this observation, includinghybridization and MO approaches, have been worked out, but we won’t cover themin this course.

14.Cl

ClPCl

Cl

F Be F180° H H

C:

< 120°F F

O

:

< 109.5°

:

+

109.5°

O OS

:

< 120°

Br

F

F

F

<90°Sb

F

F

F

F

F

no deviationsfrom 90, 120° angles

BrF

F F

F

F

:

angles < 90°

ICl

Cl Cl

Cl

:

square planar, 90° angles

:

–

F FCl

:

< 109.5°

:

<90°

15. VSEPR predicts H-C≡P: (just like HCN).

5

16. The diagram shows electrons filled in for the O2 molecule. 12 valence electrons,2 unpaired. Bond order = 1/2 (#bonding electrons – # antibonding electrons) = 1/2(8–4) = 2.

AA2A

Energy

2s

2p 2p

2s

sσ

pπ

pπ*

sσ*

pσ

pσ*

Similar analysis for cation and anions:O2+: 1 unpaired electron, BO = 2.5O2: 2 unpaired electron, BO = 2O2–: 1 unpaired electron, BO = 1.5O22–: 0 unpaired electrons, BO = 1

The bond strength increases with bond order; this is a general result for bondsbetween 2 identical atoms.

6

Problem 1.3.Element Electronic Configuration I(ev)Rb [Kr]5s1 4.18Ag [Kr]4d105s1 7.57

H atom ionization energy = Efinal – Einitial = Einfinity – En = –En (since Einfinity = 0)

= – (–hcR/n2) = 13.6eV/n2 (see text, page 19)

For n = 4, E = 0.85 eVFor n = 5, E = 0.54 eVThese values are much lower than those for Rb and Ag!Despite considerable screening of valence electrons by core electrons, and despiteelectron-electron repulsion, Zeff is so much larger for Rb and Ag than for H that ittakes an order of magnitude more energy to remove the most loosely boundelectron. [N.B. we have kept the 1/r component constant for each comparison.]

From the textbook

Page 8, Exercise 1.11. The last line refers to the "special stability of half-filledsubshell configurations." Although many textbooks comment on this (and makesimilar comments on filled shells), they are avoiding a better explanation, based onZeff, electron-electron repulsion, etc. See also #s 1.13 and 1.15 for similar comments,and please don’t give this kind of answer on your exams.

Problem 3.1Table 3.4 (p. 71) illustrates the clear trend of increasing covalent radius ondescending a group. The valence electron configuration remains constant for eachgroup member, but Zeff felt by the valence electrons actually increases as wedescend the group. But 1/r decreases because the valence orbitals are of higher n.This factor dominates, and the covalent radius increases. On traversing a period, wepopulate valence orbitals of the same n, and Zeff increases, so we expect a smallerradius as the increasing Zeff contracts the orbitals.