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Descriptive Inorganic Chemistry FIFTH EDITION Geoff Rayner-Canham Sir Wilfred Grenfell College Memorial University Tina Overton University of Hull
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Descriptive
Inorganic Chemistry
FIFTH EDITIONGeoff Rayner-Canham
Sir Wilfred Grenfell College
Memorial University
Tina Overton
University of Hull
W. H. FREEMAN AND COMPANY
NEW YORK
Publisher: Clancy Marshall
Acquisitions Editors:
Jessica Fiorillo/Kathryn Treadway
Marketing Director:
John Britch
Media Editor:
Dave Quinn
Cover and Text Designer: Vicki Tomaselli
Senior Project Editor:
Mary Louise Byrd
Illustrations:
Network Graphics/Aptara
Senior Illustration Coordinator:
Bill Page
Production Coordinator:
Susan Wein
Composition: Aptara
Printing and Binding: World Color Versailles
Library of Congress Control Number: 2009932448
ISBN-13: 978-1-4292-2434-5
ISBN-10: 1-4292-1814-2
@2010, 2006, 2003, 2000 by W. H. Freeman and CompanyAll rights reserved
Printed in the United States of America
First printing
W. H. Freeman and Company
41 Madison Avenue
New York, NY 10010
Houndmills, Basingstoke RG21 6XS, England
www.whfreeman.com CHAPTER 1 The Electronic Structure of the Atom: A Review 1CHAPTER 2 An Overview of the Periodic Table 19
CHAPTER 3 Covalent Bonding 41
CHAPTER 4 Metallic Bonding 81
CHAPTER 5 Ionic Bonding 93
CHAPTER 6 Inorganic Thermodynamics 113
CHAPTER 7 Solvent Systems and Acid-Base Behavior 137CHAPTER 8 Oxidation and Reduction 167
CHAPTER 9 Periodic Trends 191
CHAPTER 10 Hydrogen 227
CHAPTER 11 The Group 1 Elements: The Alkali Metals 245 CHAPTER 12 The Group 2 Elements: The Alkaline Earth Metals 271CHAPTER 13 The Group 13 Elements 291
CHAPTER 14 The Group 14 Elements 315
CHAPTER 15 The Group 15 Elements: The Pnictogens 363 CHAPTER 16 The Group 16 Elements: The Chalcogens 409 CHAPTER 17 The Group 17 Elements: The Halogens 453 CHAPTER 18 The Group 18 Elements: The Noble Gases 487CHAPTER 19 Transition Metal Complexes 499
CHAPTER 20 Properties of the 3d Transition Metals 533 CHAPTER 21 Properties of the 4d and 5d Transition Metals 579CHAPTER 22 The Group 12 Elements 599
CHAPTER 23 Organometallic Chemistry 611
On the Web www.whfreeman.com/descriptive5e
CHAPTER 24 The Rare Earth and Actinoid Elements 651wAppendices
A-1 Index I-1Overview
iiiThis page intentionally left blank
Contents
What Is Descriptive Inorganic Chemistry? xiii
Preface xv
Acknowledgments xix
Dedication xxi
CHAPTER 1
The Electronic Structure of the Atom:
A Review 1
Atomic Absorption Spectroscopy 2
1.1 The Schrödinger Wave Equation and Its
Signifi cance 3
1.2 Shapes of the Atomic Orbitals 5
1.3 The Polyelectronic Atom 9
1.4 Ion Electron Confi gurations 14
1.5 Magnetic Properties of Atoms 15
1.6 Medicinal Inorganic Chemistry:
An Introduction 16CHAPTER 2
An Overview of the Periodic Table 19
2.1 Organization of the Modern Periodic Table 21
2.2 Existence of the Elements 23
2.3 Stability of the Elements and Their Isotopes 24
The Origin of the Shell Model of the Nucleus 26
2.4 Classifi cations of the Elements 27
2.5 Periodic Properties: Atomic Radius 29
2.6 Periodic Properties: Ionization Energy 33
2.7 Periodic Properties: Electron Affi nity 35
Alkali Metal Anions 37
2.8 The Elements of Life 37
CHAPTER 3
Covalent Bonding 41
3.1 Models of Covalent Bonding 42
3.2 Introduction to Molecular Orbitals 43
3.3 Molecular Orbitals for Period 1 Diatomic Molecules 44
3.4 Molecular Orbitals for Period 2 Diatomic Molecules 46
3.5 Molecular Orbitals for Heteronuclear Diatomic Molecules 50
3.6 A Brief Review of Lewis Structures 51
3.7 Partial Bond Order 53
3.8 Formal Charge 54
3.9 Valence-Shell Electron-Pair Repulsion Rules 54
3.10 The Valence-Bond Concept 59
3.11 Network Covalent Substances 61
3.12 Intermolecular Forces 63
The Origins of the Electronegativity Concept 65
3.13 Molecular Symmetry 66
3.13 Symmetry and Vibrational Spectroscopy 72
Transient Species-A New Direction for Inorganic
Chemistry 74
3.15 Covalent Bonding and the Periodic Table 78
CHAPTER 4
Metallic Bonding 81
4.1 Metallic Bonding 81
4.2 Bonding Models 82
4.3 Structure of Metals 84
4.4 Unit Cells 86
4.5 Alloys 87
Memory Metal: The Shape of Things to Come 88
4.6 Nanometal Particles 89
4.7 Magnetic Properties of Metals 90
CHAPTER 5
Ionic Bonding 93
5.1 The Ionic Model and the Size of Ions 93
5.2 Hydrated Salts 95
5.3 Polarization and Covalency 96
5.4 Ionic Crystal Structures 99
5.5 Crystal Structures Involving Polyatomic Ions 105
5.6 The Bonding Continuum 106
Concrete: An Old Material with a New Future 109
v viCHAPTER 6
Inorganic Thermodynamics 113
6.1 Thermodynamics of the Formation
of Compounds 1146.2 Formation of Ionic Compounds 120
6.3 The Born-Haber Cycle 122
6.4 Thermodynamics of the Solution Process for Ionic Compounds 124
6.5 Formation of Covalent Compounds 127
The Hydrogen Economy 128
6.6 Thermodynamic versus Kinetic Factors 129
CHAPTER 7
Solvent Systems and Acid-Base
Behavior 137
7.1 Solvents 138
7.2 Brønsted-Lowry Acids 142
Antacids 144
7.3 Brønsted-Lowry Bases 147
Cyanide and Tropical Fish 148
7.4 Trends in Acid-Base Behavior 148
Superacids and Superbases 150
7.5 Acid-Base Reactions of Oxides 153
7.6 Lewis Theory 155
7.7 Pearson Hard-Soft Acid-Base Concepts 156
7.8 Applications of the HSAB Concept 158
7.9 Biological Aspects 161
CHAPTER 8
Oxidation and Reduction 167
8.1 Redox Terminology 167
8.2 Oxidation Number Rules 168
8.3 Determination of Oxidation Numbers from Electronegativities 169
8.4 The Difference between Oxidation Number and Formal Charge 171
8.5 Periodic Variations of Oxidation Numbers 172
8.6 Redox Equations 173
Chemosynthesis: Redox Chemistry on the
Seafl oor 175
8.7 Quantitative Aspects of Half-Reactions 176
8.8 Electrode Potentials as Thermodynamic
Functions 177
8.9 Latimer (Reduction Potential) Diagrams 178
8.10 Frost (Oxidation State) Diagrams 180
8.11 Pourbaix Diagrams 182
8.12 Redox Synthesis 184
8.13 Biological Aspects 185
CHAPTER 9
Periodic Trends 191
9.1 Group Trends 192
9.2 Periodic Trends in Bonding 195
9.3 Isoelectronic Series in Covalent Compounds 199
9.4 Trends in Acid-Base Properties 201
9.5 The (
n) Group and (n 10) GroupSimilarities 202
Chemical Topology 206
9.6 Isomorphism in Ionic Compounds 207
New Materials: Beyond the Limitations of
Geochemistry 209
9.7 Diagonal Relationships 210
Lithium and Mental Health 211
9.8 The "Knight"s Move" Relationship 212
9.9 The Early Actinoid Relationships 215
9.10 The Lanthanoid Relationships 216
9.11 "Combo" Elements 217
9.12 Biological Aspects 221
Thallium Poisoning: Two Case Histories 223
CHAPTER 10
Hydrogen 227
10.1 Isotopes of Hydrogen 228
10.2 Nuclear Magnetic Resonance 229
Isotopes in Chemistry 230
10.3 Properties of Hydrogen 231
Searching the Depths of Space for the
Trihydrogen Ion 233
10.4 Hydrides 233
10.5 Water and Hydrogen Bonding 237
Water: The New Wonder Solvent 238
10.6 Clathrates 239
Contents
vii10.7 Biological Aspects of Hydrogen
Bonding 241
Is There Life Elsewhere in Our Solar System? 242
10.8 Element Reaction Flowchart 242
CHAPTER 11
The Group 1 Elements: The Alkali
Metals 245
11.1 Group Trends 246
11.2 Features of Alkali Metal Compounds 247
11.3 Solubility of Alkali Metal Salts 249
Mono Lake 250
11.4 Lithium 252
11.5 Sodium 255
11.6 Potassium 256
11.7 Oxides 257
11.8 Hydroxides 259
11.9 Sodium Chloride 261
Salt Substitutes 261
11.10 Potassium Chloride 262
11.11 Sodium Carbonate 262
11.12 Sodium Hydrogen Carbonate 264
11.13 Ammonia Reaction 264
11.14 Ammonium Ion as a Pseudo-Alkali-Metal Ion 265
11.15 Biological Aspects 265
11.16 Element Reaction Flowcharts 266
CHAPTER 12
The Group 2 Elements: The Alkaline
Earth Metals 271
12.1 Group Trends 271
12.2 Features of Alkaline Earth Metal
Compounds 272
12.3 Beryllium 275
12.4 Magnesium 276
12.5 Calcium and Barium 278
12.6 Oxides 279
12.7 Calcium Carbonate 280
How Was Dolomite Formed? 281
12.8 Cement 282
12.9 Calcium Chloride 283
Biomineralization: A New Interdisciplinary
"Frontier" 28412.10 Calcium Sulfate 284
12.11 Calcium Carbide 285
12.12 Biological Aspects 286
12.15 Element Reaction Flowcharts 287
CHAPTER 13
The Group 13 Elements 291
13.1 Group Trends 292
13.2 Boron 293
13.3 Borides 294
Inorganic Fibers 295
13.4 Boranes 295
Boron Neutron Capture Therapy 298
13.5 Boron Halides 300
13.6 Aluminum 301
13.7 Aluminum Halides 306
13.8 Aluminum Potassium Sulfate 307
13.9 Spinels 308
13.10 Aluminides 309
13.11 Biological Aspects 309
13.12 Element Reaction Flowcharts 311
CHAPTER 14
The Group 14 Elements 315
14.1 Group Trends 316
14.2 Contrasts in the Chemistry of Carbon and Silicon 316
14.3 Carbon 318
The Discovery of Buckminsterfullerene 322
14.4 Isotopes of Carbon 325
14.5 Carbides 326
Moissanite: The Diamond Substitute 327
14.6 Carbon Monoxide 328
14.7 Carbon Dioxide 330
Carbon Dioxide, Supercritical Fluid 332
14.8 Carbonates and Hydrogen Carbonates 333
14.9 Carbon Sulfi des 335
14.10 Carbon Halides 335
14.11 Methane 338
14.12 Cyanides 339
Contents
viii14.13 Silicon 339
14.14 Silicon Dioxide 341
14.15 Silicates 343
14.16 Aluminosilicates 345
14.17 Silicones 349
Inorganic Polymers 350
14.18 Tin and Lead 351
14.19 Tin and Lead Oxides 352
14.20 Tin and Lead Halides 353
14.21 Tetraethyllead 354
TEL: A Case History 355
14.22 Biological Aspects 356
14.23 Element Reaction Flowcharts 359
CHAPTER 15
The Group 15 Elements:
The Pnictogens 363
15.1 Group Trends 364
15.2 Contrasts in the Chemistry
of Nitrogen and Phosphorus 36515.3 Overview of Nitrogen Chemistry 368
The First Dinitrogen Compound 369
15.4 Nitrogen 369
Propellants and Explosives 370
15.5 Nitrogen Hydrides 371
Haber and Scientifi c Morality 374
15.6 Nitrogen Ions 377
15.7 The Ammonium Ion 378
15.8 Nitrogen Oxides 379
15.9 Nitrogen Halides 384
15.10 Nitrous Acid and Nitrites 385
15.11 Nitric Acid and Nitrates 386
15.12 Overview of Phosphorus Chemistry 389
15.13 Phosphorus 390
Nauru, the World"s Richest Island 391
15.14 Phosphine 393
15.15 Phosphorus Oxides 393
15.16 Phosphorus Chlorides 394
15.17 Phosphorus Oxo-Acids and Phosphates 395
15.18 The Pnictides 399
15.19 Biological Aspects 399
Paul Erhlich and His "Magic Bullet" 401
15.29 Element Reaction Flowcharts 402
CHAPTER 16
The Group 16 Elements:
The Chalcogens 409
16.1 Group Trends 410
16.2 Contrasts in the Chemistry of
Oxygen and Sulfur 411
16.3 Oxygen 412
Oxygen Isotopes in Geology 412
16.4 Bonding in Covalent Oxygen Compounds 418
16.5 Trends in Oxide Properties 419
16.6 Mixed-Metal Oxides 421
New Pigments through Perovskites 422
16.7 Water 422
16.8 Hydrogen Peroxide 424
16.9 Hydroxides 424
16.10 The Hydroxyl Radical 426
16.11 Overview of Sulfur Chemistry 426
16.12 Sulfur 427
Cosmochemistry: Io, the Sulfur-Rich Moon 428
16.13 Hydrogen Sulfi de 431
16.14 Sulfi des 432
Disulfi de Bonds and Hair 432
16.15 Sulfur Oxides 434
16.16 Sulfi tes 437
16.17 Sulfuric Acid 438
16.18 Sulfates and Hydrogen Sulfates 440
16.19 Other Oxy-Sulfur Anions 441
16.20 Sulfur Halides 443
16.21 Sulfur-Nitrogen Compounds 445
16.22 Selenium 445
16.23 Biological Aspects 446
16.24 Element Reaction Flowcharts 448
CHAPTER 17
The Group 17 Elements: The Halogens 453
17.1 Group Trends 454
17.2 Contrasts in the Chemistry of Fluorine and Chlorine 455
17.3 Fluorine 458
The Fluoridation of Water 459
17.4 Hydrogen Fluoride and Hydrofl uoric Acid 460
17.5 Overview of Chlorine Chemistry 462
Contents
ix17.6 Chlorine 463
17.7 Hydrochloric Acid 464
17.8 Halides 465
17.9 Chlorine Oxides 469
17.10 Chlorine Oxyacids and Oxyanions 471
Swimming Pool Chemistry 473
The Discovery of the Perbromate Ion 474
17.11 Interhalogen Compounds and
Polyhalide Ions 475
17.12 Cyanide Ion as a Pseudo-halide Ion 477
17.13 Biological Aspects 478
17.14 Element Reaction Flowcharts 481
CHAPTER 18
The Group 18 Elements:
The Noble Gases 487
18.1 Group Trends 488
18.2 Unique Features of Helium 489
18.3 Uses of the Noble Gases 489
18.4 A Brief History of Noble Gas
Compounds 491
Is It Possible to Make Compounds of the
Early Noble Gases? 492
18.5 Xenon Fluorides 492
18.6 Xenon Oxides 494
18.7 Other Noble Gas Compounds 495
18.8 Biological Aspects 495
18.9 Element Reaction Flowchart 496
CHAPTER 19
Transition Metal Complexes 499
19.1 Transition Metals 499
19.2 Introduction to Transition Metal
Complexes 500
19.3 Stereochemistries 502
19.4 Isomerism in Transition Metal Complexes 503
Platinum Complexes and Cancer Treatment 506
19.5 Naming Transition Metal Complexes 507
19.6 An Overview of Bonding Theories of Transition Metal Compounds 510
19.7 Crystal Field Theory 511
19.8 Successes of Crystal Field Theory 517
The Earth and Crystal Structures 521
19.9 More on Electronic Spectra 521
19.10 Ligand Field Theory 523
19.11 Thermodynamic versus Kinetic Factors 525
19.12 Synthesis of Coordination Compounds 526
19.13 Coordination Complexes and the HSAB Concept 527
19.14 Biological Aspects 529
CHAPTER 20
Properties of the 3d Transition
Metals 533
20.1 Overview of the 3d Transition Metals 534
20.2 Group 4: Titanium 536
20.3 Group 5: Vanadium 537
20.4 Group 6: Chromium 538
20.5 Group 7: Manganese 544
Mining the Seafl oor 545
20.6 Group 8: Iron 549
20.7 Group 9: Cobalt 558
20.8 Group 10: Nickel 562
20.9 Group 11: Copper 563
20.10 Biological Aspects 569
20.11 Element Reaction Flowcharts 572
CHAPTER 21
Properties of the 4d and 5d
Transition Metals 579
21.1 Comparison of the Transition Metals 580
21.2 Features of the Heavy Transition Metals 581
21.3 Group 4: Zirconium and Hafnium 584
21.4 Group 5: Niobium and Tantalum 585
21.5 Group 6: Molybdenum and Tungsten 586
21.6 Group 7: Technetium and Rhenium 587
Technetium: The Most Important
Radiopharmaceutical 588
21.7 The Platinum Group Metals 589
21.8 Group 8: Ruthenium and Osmium 590
21.9 Group 9: Rhodium and Iridium 591
21.10 Group 10: Palladium and Platinum 591
21.11 Group 11: Silver and Gold 591
21.12 Biological Aspects 594
Contents
xCHAPTER 22
The Group 12 Elements 599
22.1 Group Trends 600
22.2 Zinc and Cadmium 600
22.3 Mercury 603
22.4 Biological Aspects 605
Mercury Amalgam in Teeth 607
22.5 Element Reaction Flowchart 608
CHAPTER 23
Organometallic Chemistry 611
23.1 Introduction to Organometallic
Compounds 612
23.2 Naming Organometallic Compounds 612
23.3 Counting Electrons 613
23.4 Solvents for Organometallic Chemistry 614
23.5 Main Group Organometallic Compounds 615
Grignard Reagents 618
The Death of Karen Wetterhahn 623
23.6 Organometallic Compounds of the Transition Metals 623
23.7 Transition Metal Carbonyls 625
23.8 Synthesis and Properties of Simple Metal Carbonyls 630
23.9 Reactions of Transition Metal Carbonyls 632
23.10 Other Carbonyl Compounds 633
23.11 Complexes with Phosphine Ligands 634
23.12 Complexes with Alkyl, Alkene, and Alkyne Ligands 635
Vitamin B
12 -A Naturally OccurringOrganometallic Compound 638
23.13 Complexes with Allyl and 1,3-Butadiene Ligands 639
23.14 Metallocenes 640
23.15 Complexes with
6 -Arene Ligands 64223.16 Complexes with Cycloheptatriene and Cyclooctatetraene Ligands 643
23.17 Fluxionality 643
23.18 Organometallic Compounds in Industrial Catalysis 644
CHAPTER 24
ON THE WEB www.whfreeman.com/descriptive5e
The Rare Earth and Actinoid
Elements 651w
24.1 The Group 3 Elements 653w
24.2 The Lanthanoids 653w
Superconductivity 655w
23.3 The Actinoids 656w
24.4 Uranium 659w
A Natural Fission Reactor 661w
24.5 The Postactinoid Elements 662w
APPENDICES
Appendix 1 Thermodynamic Properties of
Some Selected Inorganic
Compounds A-1
Appendix 2 Charge Densities of Selected
Ions A-13
Appendix 3 Selected Bond Energies A-16
Appendix 4 Ionization Energies of Selected
Metals A-18
Appendix 5 Electron Affi nities of Selected
Nonmetals A-20
Appendix 6 Selected Lattice Energies A-21
Appendix 7 Selected Hydration Enthalpies A-22
Appendix 8 Selected Ionic Radii A-23
ON THE WEB www.whfreeman.com/descriptive5e
Appendix 9 Standard Half-Cell Electrode
Potentials of Selected
Elements A-25w
ON THE WEB www.whfreeman.com/descriptive5e
Appendix 10 Electron Confi guration
of the Elements A-35wINDEX I-1
Contents
What Is Descriptive Inorganic Chemistry?
D escriptive inorganic chemistry was traditionally concerned with the prop - erties of the elements and their compounds. Now, in the renaissance of the subject, with the synthesis of new and novel materials, the properties are being linked with explanations for the formulas and structures of compou nds together with an understanding of the chemical reactions they undergo. In addition, we are no longer looking at inorganic chemistry as an isolated subject but as a part of essential scientifi c knowledge with applications throughout science and our lives. Because of a need for greater contextualization, we have added more features and more applications. In many colleges and universities, descriptive inorganic chemistry is offered as a sophomore or junior course. In this way, students come to know something of the fundamental properties of important and interesting elements and their compounds. Such knowledge is important for careers not only in pure or applied chemistry but also in pharmacy, medicine, geology, and environmental science. This course can then be followed by a junior or senior course that focuse s on the theoretical principles and the use of spectroscopy to a greater dept h than is covered in a descriptive text. In fact, the theoretical course builds nicely on the descriptive background. Without the descriptive grounding, however, the theory becomes sterile, uninteresting, and irrelevant. Education has often been a case of the "swinging pendulum," and this has been true of inorganic chemistry. Up until the 1960s, it was very much pure descriptive, requiring exclusively memorization. In the 1970s and 1980s, upper-level texts focused exclusively on the theoretical principles. Now it is ap- parent that descriptive is very important"not the traditional memorization of facts but the linking of facts, where possible, to underlying principles. Students need to have modern descriptive inorganic chemistry as part of their edu ca- tion. Thus, we must ensure that chemists are aware of the "new descriptive inorganic chemistry." xiThis page intentionally left blank
Preface
Inorganic chemistry goes beyond academic interest: it is an im- portant part of our lives. I norganic chemistry is interesting-more than that-it is exciting! S o much of our twenty-fi rst-century science and technology rely on natural and syn- thetic materials, often inorganic compounds, many of which are new and novel. Inorganic chemistry is ubiquitous in our daily lives: household products, some pharmaceuticals, our transportation-both the vehicles themselves and the synthesis of the fuels-battery technology, and medical treatments. There is the industrial aspect, the production of all the chemicals required to drive our economy, everything from steel to sulfuric acid to glass and cement. Environ- mental chemistry is largely a question of the inorganic chemistry of the atmo- sphere, water, and soil. Finally, there are the profound issues of the inorganic chemistry of our planet, the solar system, and the universe. This textbook is designed to focus on the properties of selected interest ing, important, and unusual elements and compounds. However, to understand inorganic chemistry, it is crucial to tie this knowledge to the underlying chemi- cal principles and hence provide explanations for the existence and beha vior of compounds. For this reason, almost half the chapters survey the relevant concepts of atomic theory, bonding, intermolecular forces, thermodynamics, acid-base behavior, and reduction-oxidation properties as a prelude to, and preparation for, the descriptive material. For this fth edition, the greatest change has been the expansion of coverage of the 4 d and 5 d transition metals to a whole chapter. The heavier transition metals have unique trends and patterns, and the new chapter highlights these. Having an additional chapter on transition met- als also better balances the coverage between the main group elements and the transition elements. Also, the fth edition has a second color. With the addition of a second color, gures are much easier to understand, and tables and text are easier to read. On a chapter-by-chapter basis, the signi cant improvements are as follows: Chapter 1: The Electronic Structure of the Atom: A Review The Introductionand Section 1.3, The Polyelectronic Atom, have been revised.Chapter 3: Covalent Bonding
Section 3.11,
Network Covalent Substances, has a new subsection: AmorphousSilicon.
Chapter 4: Metallic Bonding
Section 4.6,
Nanometal Particles, was added.Section 4.7,
Magnetic Properties of Metals, was added.
xiii xivChapter 5: Ionic Bonding
Section 5.3,
Polarization and Covalency, has a new subsection: The Ionic-Covalent Boundary.
Section 5.4, Ionic Crystal Structures, has a new subsection: Quantum Dots.Chapter 9: Periodic Trends
Section 9.3,
Isoelectronic Series in Covalent Compounds, has been revised and improved.Section 9.8,
The "Knight"s Move" Relationship, has been revised and improved.Chapter 10: Hydrogen
Section 10.4,
Hydrides, has a revised and expanded subsection: Ionic Hydrides.Chapter 11: The Group 1 Elements
Section 11.14,
Ammonium Ion as a Pseudo...Alkali-Metal Ion, moved fromChapter 9.
Chapter 13: The Group 13 Elements
Section 13.10,
Aluminides, was added.
Chapter 14: The Group 14 Elements
Section 14.2,
Contrasts in the Chemistry of Carbon and Silicon, was added.Section 14.3,
Carbon, has a new subsection: Graphene. Section 14.7, Carbon Dioxide, has a new subsection: Carbonia.Chapter 15: The Group 15 Elements
Section 15.2,
Contrasts in the Chemistry of Nitrogen and Phosphorus, was added.Section 15.18,
The Pnictides, was added.
Chapter 16: The Group 16 Elements
Section 16.2,
Contrasts in the Chemistry of Oxygen and Sulfur, was added.Section 16.14,
Sulfi des, has a new subsection: Disulfi des.
Chapter 17: The Group 17 Elements
Section 17.2,
Contrasts in the Chemistry of Fluorine and Chlorine, was added.Section 17.12,
Cyanide Ion as a Pseudo-halide Ion, moved from Chapter 9.Chapter 18: The Group 18 Elements
Section 18.7,
Other Noble Gas Compounds, was added.
Chapter 19: Transition Metal Complexes
Section 19.10,
Ligand Field Theory, was added.Chapter 20: Properties of the 3
d Transition MetalsSection 20.1,
Overview of the 3d Transition Metals, was added.
Chapter 21: Properties of the 4
d and 5 d Transition Metals N EW CHAPTERadded (for details, see the previous page).Chapter 24: The Rare Earth and Actinoid Elements
This chapter has been signifi cantly revised with the new subsectionsScandium,
Yttrium, and Thorium.
Preface
xv ALSOVideo Clips
Descriptive inorganic chemistry by defi nition is visual, so what better way to appreciate a chemical reaction than to make it visual? We now have a series of at least 60 Web-based video clips to bring some of the reactions to life. The text has a margin icon to indicate where a reaction is illustrated.Text Figures and Tables
All the illustrations and tables in the book are available as .jpg fi les for inclusion in PowerPoint presentations on the instructor side of the Web site at www.whfreeman.com/descriptive5e.Additional Resources
A list of relevant
S CIENTIFIC AMERICANarticles is found on the text Web site atwww.whfreeman.com/descriptive5e. The text has a margin icon to indicate where aScientifi c American article is available.
Supplements
The Student Solutions Manual, ISBN: 1-4292-2434-7 contains the worked solutions to all the odd-numbered end-of-chapter problems. The Companion Web Sitewww.whfreeman.com/descriptive5e Contains the following student-friendly materials: Chapter 24: The Rare Earth and Actinoid Elements, Appendices, Lab Experiments, Tables, and over 50 useful videos of elements and metals in reactions and oxidations.Instructor"s Resource CD-ROM, ISBN: 1-4292-2428-2
Includes PowerPoint and videos as well as all text art and solutions to all prob- lems in the book. This textbook was written to pass on to another generation our fascinatio n with descriptive inorganic chemistry. Thus, the comments of readers, both stu- dents and instructors, will be sincerely appreciated. Any suggestions for added or updated additional readings are also welcome. Our current e-mail addresses aregrcanham@swgc.mun.ca and T.L.Overton@hull.ac.uk.Preface
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Acknowledgments
M any thanks must go to the team at W. H. Freeman and Company who have contributed their talents to the fi ve editions of this book. We offer our sincere gratitude to the editors of the fi fth edition, Jessica Fiorillo, Kathryn Treadway, and Mary Louise Byrd; of the fourth edition, Jessica Fiorillo, Jenness Crawford, and Mary Louise Byrd; of the third edition, Jessica Fiorillo and Guy Copes; of the second edition, Michelle Julet and Mary Louise Byrd; and a special thanks to Deborah Allen, who bravely commissioned the fi rst edition of the text. Each one of our fabulous editors has been a source of encouragement, support, and helpfulness. We wish to acknowledge the following reviewers of this edition, whose criticisms and comments were much appreciated: Theodore Betley at Harvard University; Dean Campbell at Bradley University; Maria Contel at Brooklyn College (CUNY); Gerry Davidson at St. Francis College; Maria Derosa at Carleton University; Stan Duraj at Cleveland State University; Dmitri Giarkios at Nova Southeastern University; Michael Jensen at Ohio University-Main Campus; David Marx at the University of Scranton; Joshua Moore at Tennessee State University-Nashville; Stacy O"Reilly at Butler University; William Pen- nington at Clemson University; Daniel Rabinovich at the University of North Carolina at Charlotte; Hal Rogers at California State University-Fullerton; Thomas Schmedake at the University of North Carolina at Charlotte; Bradley Smucker at Austin College; Sabrina Sobel at Hofstra University; Ronald Strange at Fairleigh Dickinson University-Madison; Mark Walters at New York University; Yixuan Wang at Albany State University; and Juchao Yan at Eastern New Mexico University; together with prereviewers: Londa Borer at California State University-Sacramento; Joe Fritsch at Pepperdine Univer- sity; Rebecca Roesner at Illinois Wesleyan University, and Carmen Works atSonoma College.
We acknowledge with thanks the contributions of the reviewers of the fourth edition: Rachel Narehood Austin at Bates College; Leo A. Bares at the University of North Carolina"Asheville; Karen S. Brewer at Hamilton College; Robert M. Burns at Alma College; Do Chang at Averett University; Georges Dénès at Concordia University; Daniel R. Derringer at Hollins University; Carl P. Fictorie at Dordt College; Margaret Kastner at Bucknell University; Michael Laing at the University of Natal, Durban; Richard H. Langley at Stephen F. Austin State University; Mark R. McClure at the University of North Carolina at Pembroke; Louis Mercier at Laurentian University; G. Merga at Andrews University; Stacy O"Reilly at Butler University; Larry D. Pedersen at College Misercordia; Robert D. Pike at the College of William and Mary; William Quintana at New Mexico State University; David F. Rieck at Salisbury University; John Selegue at the University of Kentucky; Melissa M. Strait at Alma College; Daniel J. Williams at Kennesaw State University; Juchao Yan at Eastern New Mexico University; and Arden P. Zipp at the State University ofNew York at Cortland.
xvii xviii And the contributions of the reviewers of the third edition: François Caron at Laurentian University; Thomas D. Getman at Northern Michigan Univer- sity; Janet R. Morrow at the State University of New York at Buffalo; Robert D. Pike at the College of William and Mary; Michael B. Wells at Cambell Uni- versity; and particularly Joe Takats of the University of Alberta for his compre- hensive critique of the second edition. And the contributions of the reviewers of the second edition: F. C. Hentz at North Carolina State University; Michael D. Johnson at New Mexico State University; Richard B. Kaner at the University of California, Los Angeles; Richard H. Langley at Stephen F. Austin State University; James M. Mayer at the University of Washington; Jon Melton at Messiah College; Joseph S. Merola at Virginia Technical Institute; David Phillips at Wabash College; John R. Pladziewicz at the University of Wisconsin, Eau Claire; Daniel Rabinovich at the University of North Carolina at Charlotte; David F. Reich at Salisbury State University; Todd K. Trout at Mercyhurst College; Steve Watton at the Virginia Commonwealth University; and John S. Wood at the University ofMassachusetts, Amherst.
Likewise, the reviewers of the fi rst edition: E. Joseph Billo at Boston Col- lege; David Finster at Wittenberg University; Stephen J. Hawkes at Oregon State University; Martin Hocking at the University of Victoria; Vake Marganian at Bridgewater State College; Edward Mottel at the Rose-Hulman Institute of Technology; and Alex Whitla at Mount Allison University. As a personal acknowledgment, Geoff Rayner-Canham wishes to especial- ly thank three teachers and mentors who had a major infl uence on his career: Briant Bourne, Harvey Grammar School; Margaret Goodgame, Imperial Col- lege, London University; and Derek Sutton, Simon Fraser University. And he expresses his eternal gratitude to his spouse, Marelene, for her support and encouragement. Tina Overton would like to thank her colleague Phil King for his invaluab le suggestions for improvements and his assistance with the illustrations. Thanks must also go to her family, Dave, John, and Lucy, for their patience during the months when this project fi lled all her waking hours.Acknowledgments
Dedication
C hemistry is a human endeavor. New discoveries are the result of the work of enthusiastic people and groups of people who want to explore the molecular world. We hope that you, the reader, will come to share our own fascination with inorganic chemistry. We have chosen to dedicate this book to two scientists who, for very different reasons, never did receive the ultimate accolade of a Nobel Prize.Henry Moseley (1887...1915)
Although Mendeleev is identifi ed as the discoverer of the peri- odic table, his version was based on an increase in atomic mass. In some cases, the order of elements had to be reversed to match properties with location. It was a British scientist, Henry Moseley, who put the periodic table on a much fi rmer footing by discov- ering that, on bombardment with electrons, each element emit- ted X-rays of characteristic wavelengths. The wavelengths fi tted a formula related by an integer number unique to each element. We know that number to be the number of protons. With the es- tablishment of the atomic number of an element, chemists at last knew the fundamental organization of the table. Sadly, Moseley was killed at the battle of Gallipoli in World War I. Thus, one of the brightest scientifi c talents of the twentieth century died at the age of 27. The famous American scientist Robert Milliken commented: "Had the European War had no other result than the snuffi ng out of this young life, that alone would make it one of the most hideous and most irreparable cr imes in history." Unfortunately, Nobel Prizes are only awarded to living scientists. In 1924, the discovery of element 43 was claimed, and it was named mose- leyum; however, the claim was disproved by the very method that Moseley had pioneered. xix xxLise Meitner (1878-1968)
In the 1930s, scientists were bombarding atoms of heavy elements such as uranium with subatomic particles to try to make new ele- ments and extend the periodic table. Austrian scientist Lise Meit- ner had shared leadership with Otto Hahn of the German research team working on the synthesis of new elements; the team thought they had discovered nine new elements. Shortly after the claimed discovery, Meitner was forced to fl ee Germany because of her Jewish ancestry, and she settled in Sweden. Hahn reported to her that one of the new elements behaved chemically just like barium. During a famous "walk in the snow" with her nephew, physicist Otto Frisch, Meitner realized that an atomic nucleus could break in two just like a drop of water. No wonder the element formed behaved like barium: it was barium! Thus was born the concept of nuclear fi ssion. She informed Hahn of her proposal. When Hahn wrote the research paper on the work, he barely mentioned the vital contribution of Meitner and Frisch. As a result, Hahn and his colleague Fritz Strassmann received the Nobel Prize. Meitner"s fl ash of genius was ignored. Only recently has Meitner received the acclaim she deserved by the namin g of an element after her, element 109, meitnerium.Additional reading
Heibron, J. L.
H. G. J. Moseley. University of California Press, Berkeley, 1974.Rayner-Canham, M. F., and G. W. Rayner-Canham.
Women in Chemistry:
Their Changing Roles from Alchemical Times to the Mid-Twentieth Century.Chemical Heritage Foundation, Philadelphia, 1998.
Sime, R. L.
Lise Meitner: A Life in Physics. University of California Press,Berkeley, 1996.
Weeks, M. E., and H. M. Leicester.
Discovery of the Elements, 7th ed. Journal of Chemical Education, Easton, PA, 1968.Dedication
I saac Newton was the original model for the absentminded professor. Supposedly, he always timed the boiled egg he ate at breakfast; one morning, his maid found him standing by the pot of boiling water, hold- ing an egg in his hand and gazing intently at the watch in the bottom of the pot! Nevertheless, it was Newton who initiated the study of the electronic structure of the atom in about 1700, when he noticed that the passage of sunlight through a prism produced a continuous visible spectrum. Much later, in 1860, Robert Bunsen (of burner fame) inves- tigated the light emissions from " ames and gases. Bunsen observed that the emission spectra, rather than being continuous, were series of colored lines (line spectra). The proposal that electrons existed in concentric shells had its origin in the research of two overlooked pioneers: Johann Jakob Balmer, a Swiss mathematician, and Johannes Robert Rydberg, a Swedish physicist. After an undistinguished career in mathematics, in 1885, at the age of60, Balmer studied the visible emission lines of the hydrogen atom and
found that there was a mathematical relationship between the wave- lengths. Following from Balmers work, in 1888, Rydberg deduced a more general relationship: 1 l5R H a1 n 2f 21n 2 i b wherel is the wavelength of the emission line, R H is a constant, later known as the Rydberg constant, and n f and n i are integers. For the visible lines seen by Balmer and Rydberg, n f had a value of 2. The Rydberg formula received further support in 1906, when Theodore Lyman found a series of lines in the far-ultraviolet spectrum of hydrogen,
1.1 The Schrödinger Wave
Equation and Its Signi cance
Atomic Absorption Spectroscopy
1.2 Shapes of the Atomic Orbitals
1.3 The Polyelectronic Atom
1.4 Ion Electron Con gurations
1.5 Magnetic Properties of Atoms
1.6 Medicinal Inorganic Chemistry:
An Introduction
The Electronic Structure
of the Atom: A ReviewCHAPTER 1
1 To understand the behavior of inorganic compounds, we need to study the nature of chemical bonding. Bonding, in turn, relates to the behavio r of electrons in the constituent atoms. Our study of inorganic chemistry, therefore, starts with a review of the models of the atom and a survey of the probability models applications to the electron con gurations of atoms and ions. CHAPTER 1 The Electronic Structure of the Atom: A Review2 corresponding to the Rydberg formula with n f51. Then in 1908, Friedrich
Paschen discovered a series of far-infrared hydrogen lines, fi tting the equation with n f 53.In 1913, Niels Bohr, a Danish physicist, became aware of Balmer"s and Rydberg"s experimental work and of the Rydberg formula. At that time, he was trying to combine Ernest Rutherford"s planetary model for electrons in an atom with Max Planck"s quantum theory of energy exchanges. Bohr contended that an electron orbiting an atomic nucleus could only do so at certain fi xed distances and that whenever the electron moved from a higher to a lower orbit, the atom emitted characteristic electromagnetic radiation. Rydberg had deduced his equation from experimental observations of atomic hydrogen emission spectra. Bohr was able to derive the same equation from quantum theory, showing that his theoretical work meshed with reality. From this result, the Rutherford-Bohr model of the atom of concentric elec- tron "shells" was devised, mirroring the recurring patterns in the periodic table of the elements (Figure 1.1). Thus the whole concept of electron energy levels can be traced back to Rydberg. In recognition of Rydberg"s contribution, excited atoms with very high values of the principal quantum number, n, are called
Rydberg atoms.
However, the Rutherford-Bohr model had a number of fl aws. For example, the spectra of multi-electron atoms had far more lines than the simple B ohr model predicted. Nor could the model explain the splitting of the spectral lines in a magnetic fi eld (a phenomenon known as the Zeeman effect). Within a short time, a radically different model, the quantum mechanical model, was proposed to account for these observations. n 3 n 2 n 1 Ze E hvFIGURE 1.1 The Rutherford-
Bohr electron-shell model of the
atom, showing the n51, 2, and 3 energy levels. A glowing body, such as the Sun, is expected to emit a continuous spectrum of electromagnetic radiation. However, in the early nineteenth century, a German sci- entist, Josef von Fraunhofer, noticed that the visible spec- trum from the Sun actually contained a number of dark bands. Later investigators realized that the bands were the result of the absorption of particular wavelengths by cooler atoms in the "atmosphere" above the surface of the Sun. The electrons of these atoms were in the ground state, and they were absorbing radiation at wavelengths corresponding to the energies needed to excite them to higher energy states. A study of these "negative" spectra led to the discovery of helium. Such spectral studies are still of great importance in cosmochemistry-the study of the chemical composition of stars. In 1955, two groups of scientists, one in Australia and the other in Holland, fi nally realized that the absorptionmethod could be used to detect the presence of elements at very low concentrations. Each element has a particu-lar absorption spectrum corresponding to the various separations of (differences between) the energy levels in its atoms. When light from an atomic emission source is passed through a vaporized sample of an element, the particular wavelengths corresponding to the various en-ergy separations will be absorbed. We fi nd that the higher
the concentration of the atoms, the greater the proportion of the light that will be absorbed. This linear relationship between light absorption and concentration is known as Beers law. The sensitivity of this method is extremely high, and concentrations of parts per million are easy to determine; some elements can be detected at the parts per billion level. Atomic absorption spectroscopy has now become a routine analytical tool in chemistry, metal- lurgy, geology, medicine, forensic science, and many other fi elds of science-and it simply requires the movement of electrons from one energy level to another.Atomic Absorption Spectroscopy
31.1 The Schrödinger Wave Equation and Its Signifi cance
The more sophisticated quantum mechanical model of atomic structure was derived from the work of Louis de Broglie. De Broglie showed that, just as elec- tromagnetic waves could be treated as streams of particles (photons), moving particles could exhibit wavelike properties. Thus, it was equally valid to picture electrons either as particles or as waves. Using this wave-particle duality, Erwin Schrödinger developed a partial differential equation to represent th e behavior of an electron around an atomic nucleus. One form of this equation, given here for a one-electron atom, shows the relationship between the wave function of the electron, C, and E and V, the total and potential energies of the system, re- spectively. The second differential terms relate to the wave function along each of the Cartesian coordinates x,y, and z, while m is the mass of an electron, and h is Planck"s constant. 0 2 ° 0x 2 10 2 ° 0 y 2 10 2 ° 0z 2 18p 2 m h 21E2V2°50
The derivation of this equation and the method of solving it are in the r ealm of physics and physical chemistry, but the solution itself is of great importance to inorganic chemists. We should always keep in mind, however, that the wave equation is simply a mathematical formula. We attach meanings to the solution simply because most people need concrete images to think about subatomic phenomena. The conceptual models that we create in our macroscopic world cannot hope to reproduce the subatomic reality. It was contended that the real meaning of the equation could be found from the square of the wave function, C 2 , which represents the probability of fi nding the electron at any point in the region surrounding the nucleus. There are a number of solutions to a wave equation. Each solution describes a different orbital and, hence, a different probability distribution for an elec- tron in that orbital. Each of these orbitals is uniquely defi ned by a set of three integers: n,l, and m l . Like the integers in the Bohr model, these integers are also called quantum numbers. In addition to the three quantum numbers derived from the original theor y, a fourth quantum number had to be defi ned to explain the results of an experi- ment in 1922. In this experiment, Otto Stern and Walther Gerlach found that passing a beam of silver atoms through a magnetic fi eld caused about half the atoms to be defl ected in one direction and the other half in the opposite direc- tion. Other investigators proposed that the observation was the result of two different electronic spin orientations. The atoms possessing an electron with one spin were defl ected one way, and the atoms whose electron had the oppo- site spin were defl ected in the opposite direction. This spin quantum number was assigned the symbol m s . The possible values of the quantum numbers are defi ned as follows: n , the principal quantum number, can have all positive integer values from 1 to q.1.1 The Schrödinger Wave Equation and Its Signifi cance
CHAPTER 1 The Electronic Structure of the Atom: A Review4 l , the angular momentum quantum number, can have all integer values from n21 to 0. m l , the magnetic quantum number, can have all integer values from 1l through 0 to 2l. m s , the spin quantum number, can have values of 1 1 2 and 2 1 2 . When the value of the principal quantum number is 1, there is only one possible set of quantum numbers n ,l, and m l (1, 0, 0), whereas for a principal quantum number of 2, there are four sets of quantum numbers (2, 0, 0; 2, 1, ...1;2, 1, 0; 2, 1,
11). This situation is shown diagrammatically in Figure 1.2. To
identify the electron orbital that corresponds to each set of quantum nu mbers, we use the value of the principal quantum number n, followed by a letter for the angular momentum quantum number l . Thus, when n51, there is only the1s orbital.
When n52, there is one 2s orbital and three 2p orbitals (corresponding to the m l values of 11, 0, and ...1). The letters
s ,p,d, and f are derived from categories of the spectral lines: sharp, principal, diffuse, and fundamental. The correspondences are shown in Table 1.1.When the principal quantum number
n53, there are nine sets of quantum numbers (Figure 1.3). These sets correspond to one 3 s , three 3 p , and ve 3d orbitals. A similar diagram for the principal quantum number n54 would show 16 sets of quantum numbers, corresponding to one 4 s , three 4 p , ve 4d,FIGURE 1.2 The possible sets
of quantum numbers for n5 1 andn5 2. n l m l 1 s2s2p1 100011 0 02
TABLE 1.1Correspondence between angular momentum
numberl and orbital designation l Value Orbital designation 0s 1p 2d 3f1.2 Shapes of the Atomic Orbitals
Representing the solutions to a wave equation on paper is not an easy ta sk. In fact, we would need four-dimensional graph paper (if it existed) to display the complete solution for each orbital. As a realistic alternative, we break the wave equation into two parts: a radial part and an angular part. Each of the three quantum numbers derived from the wave equation rep- resents a different aspect of the orbital:The principal quantum number
n indicates the size of the orbital.The angular momentum quantum number
l represents the shape of the orbital.The magnetic quantum number
m l represents the spatial direction of the orbital.The spin quantum number
m s has little physical meaning; it merely allows two electrons to occupy the same orbital. It is the value of the principal quantum number and, to a lesser extent the angular momentum quantum number, which determines the energy of the electron. Although the electron may not literally be spinning, it behaves as if it was, and it has the magnetic properties expected for a spinning particle. An orbital diagram is used to indicate the probability of fi nding an electron at any point in space. We defi ne a location where an electron is most probablyTABLE 1.2Correspondence between angular momentum
numberl and number of orbitals l Value Number of orbitals 0 1 1 3 2 5 3 7FIGURE 1.3 The possible sets
of quantum numbers for n53. n l m l 0130112112002
3 s3p3d and seven 4 f orbitals (Table 1.2). Theoretically, we can go on and on, but as we will see, the f orbitals represent the limit of orbital types among the elements of the periodic table for atoms in their electronic ground states. 5 CHAPTER 1 The Electronic Structure of the Atom: A Review6 found as an area of high electron density . Conversely, locations with a low prob- ability are called areas of low electron density.Thes Orbitals
The s orbitals are spherically symmetric about the atomic nucleus. As the prin- cipal quantum number increases, the electron tends to be found farther from the nucleus. To express this idea in a different way, we say that, as the principal quantum number increases, the orbital becomes more diffuse. A unique fea- ture of electron behavior in an s orbital is that there is a fi nite probability of fi nding the electron close to, and even within, the nucleus. This penetration by s orbital electrons plays a role in atomic radii (see Chapter 2) and as a means of studying nuclear structure. Same-scale representations of the shapes (angular functions) of the 1 s and 2 s orbitals of an atom are compared in Figure 1.4. The volume of a 2s orbital is about four times greater than that of a 1 s orbital. In both cases, the tiny nucleus is located at the center of the spheres. These spheres represent the region in which there is a 99 percent probability of fi nding an electron. The total prob- ability cannot be represented, for the probability of fi nding an electron drops to zero only at an infi nite distance from the nucleus. The probability of fi nding the electron within an orbital will always be posi- tive (since the probability is derived from the square of the wave func tion and squaring a negative makes a positive). However, when we discuss the bonding of atoms, we fi nd that the sign related to the original wave function has impor- tance. For this reason, it is conventional to superimpose the sign of the wave function on the representation of each atomic orbital. For an s orbital, the sign is positive. In addition to the considerable difference in size between the 1 s and the 2 s orbitals, the 2 s orbital has, at a certain distance from the nucleus, a spherical surface on which the electron density is zero. A surface on which the probabil- ity of fi nding an electron is zero is called a nodal surface . When the principal quantum number increases by 1, the number of nodal surfaces also increases by 1. We can visualize nodal surfaces more clearly by plotting a graph of the r a- dial density distribution function as a function of distance from the nu cleus for any direction. Figure 1.5 shows plots for the 1 s , 2s, and 3s orbitals. These plots show that the electron tends to be farther from the nucleus as the princ ipal quantum number increases. The areas under all three curves are the same.FIGURE 1.4 Representations of
the shapes and comparative sizes of the 1 s and 2 s orbitals. 7Electrons in an
s orbital are different from those in p ,d, or f orbitals in two signifi cant ways. First, only the s orbital has an electron density that varies in the same way in every direction out from the atomic nucleus. Second, there is a fi nite probability that an electron in an s orbital is at the nucleus of the atom.Every other orbital has a node at the nucleus.
Thep Orbitals
Unlike the
s orbitals, the p orbitals consist of two separate volumes of space (lobes), with the nucleus located between the two lobes. Because there are threep orbitals, we assign each orbital a direction according to Cartesian co- ordinates: we have p x ,p y , and p z . Figure 1.6 shows representations of the three 2 p orbitals. At right angles to the axis of higher probability, there is a nodal plane through the nucleus. For example, the 2 p z orbital has a nodal surface in thexy plane. In terms of wave function sign, one lobe is positive and the other negative. FIGURE 1.5 The variation of the radial density distribution function with distance from the nucleus for electrons in the 1 s , 2s, and 3s orbitals of a hydrogen atom. 2 sDistance (nm)
0.2 0.40.6 0.80.2 0.40.6 0.81.0 1.2
Distance (nm)
Probability
1 s0.2 0.4
Distance (nm)
Probability
Probability
3 s1.2 Shapes of the Atomic Orbitals
FIGURE 1.6 Representations of
the shapes of the 2 p x , 2 p y , and 2 p z orbitals. CHAPTER 1 The Electronic Structure of the Atom: A Review8 If we compare graphs of electron density as a function of atomic radius for the 2 s orbital and a 2 p orbital (the latter plotted along the axis of higher prob- ability), we fi nd that the 2s orbital has a much greater electron density close to the nucleus than does the 2 p orbital (Figure 1.7). Conversely, the second maximum of the 2 s orbital is farther out than the single maximum of the 2 p orbital. However, the mean distance of maximum probability is the same for both orbitals.Like the
s orbitals, the p orbitals develop additional nodal surfaces within the orbital structure as the principal quantum number increases. Thus, a 3p orbital does not look exactly like a 2 p orbital since it has an additional nodal surface. However, the detailed differences in orbital shapes for a particular angular momentum quantum number are of little relevance in the context o f basic inorganic chemistry.Thed Orbitals
The fi ve d orbitals have more complex shapes. Three of them are located between the Cartesian axes, and the other two are oriented along the axes. In all cases, the nucleus is located at the intersection of the axes. Three orbitals each have four lobes that are located between pairs of axes (Figure 1.8). These orbitals are identifi ed as d xy , d xz ,andd yz . The other two d orbitals, d z 2 and d x 2 2y 2 , are shown in Figure 1.9. The d z 2 orbital looks somewhat similar to a p z orbital (see Figure 1.6), except that it has an additional doughnut-shaped ring of high electron d ensity in the xy plane. The d x 2 2y 2 orbital is identical to the d xy orbital but has been rotated through 45 8 .FIGURE 1.7The variation of
the radial density distribution function with distance from the nucleus for electrons in the 2 s and 2 p orbitals of a hydrogen atom. 2 sDistance (nm)
Probability
0.2 0.40.6 0.8
2 pDistance (nm)
Probability
0.2 0.40.6 0.8
FIGURE 1.8Representations of the shapes of the 3d
xy , 3 d xz , and 3 d yz orbitals. 9Thef Orbitals
The f orbitals are even more complex than the d orbitals. There are seven f orbitals, four of which have eight lobes. The other three look like the d z 2 orbital but have two doughnut-shaped rings instead of one. These orbitals are rarely involved in bonding, so we do not need to consider them in any detail.1.3 The Polyelectronic Atom
In our model of the polyelectronic atom, the electrons are distributed among the orbitals of the atom according to theAufbau
(building-up) principle . This simple idea proposes that, when the electrons of an atom are all in the ground state, they occupy the orbitals of lowest energy, thereby minimizing the atom"s total electronic energy. Thus, the confi guration of an atom can be described simply by adding electrons one by one until the total number required fo r the element has been reached. Before starting to construct electron confi gurations, we need to take into account a second rule: thePauli exclusion principle
. According to this rule, no two electrons in an atom may possess identical sets of the four quantum num- bers. Thus, there can be only one orbital of each three-quantum-number set per atom and each orbital can hold only two electrons, one with m s 511 2 and the other with m s 52
1 2 .