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SECOND EDITION

JAMES MARSHALL

A SEARCH FUR THE FUNDAMENTAL PRINCIPLES OF THE UNIVERSE A SEARCH FOR THE FUNDAMENTAL PRINCIPLES OF THE UNIVERSE

SECOND EDITION

JAMES LmMARSHALL Cover Images. Funeral mask of Tutankhamen; portrait. of Lavoisier and his wife, by Jacques-Louis David; Marie Curie; Carl Scheele; John Dalton, courtesy of Corbis Images. Roman coin courtesy of Raymond V. Schoder/Corbis Images. Cross-cut sections of crystals in minerals courtesy of Getty Images.

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I F'igure 1 : Catastrophe! The Mindenberg..., United Press Syndicate, Kansas City MO; 1 Figure 2: Robert Boyle, Photograph courtesy of the Smithsonian Institution, Washington DC; 3 Figure3: Honto erecttrs, as appears in Tlze Htrntan Dawn. TilneFrante, published by Time-Life, Alexandria VA. The following figures appeared in Discove~yof the Elentents, 7th Edition, Jo~rrnalof Clteniical Eclncatio~r,published by Mack Printing, Easton PA: 3 Figure 4: Wermes Trismesgistos..., 16 Figure 14: Georgius Agricola, who wrote..., 26 Figure 20 Daniel Rutherford..., 38 Figure 35: Henri Moissan prepares fluorine..., 50 Figure 46: Rene-Just Hauy, who discovered the laws of crystallography, 53 Figure 48, Don Antonio de Uloa, who gave the first definitive account, 71 Figure 63: Laboratory at Freiberg School of Mines, Germany, 73 Figure 64: Johan Gadolin, who discovered yttria ..., 73 Figure 65: Carl Mosander, who discovered lanthana, 81 Figure 68: John WiIliam Strutt, Lord Raleigh, 81 Figure 69, Sir William Ramsay, who discovered the inert gases..., 82 Figure 71: Sir Norman Lockyer, who proposed the yellow line ..., 89 Figure 76: The laboratory of M. and Mme. Curie..., 97 Figure 80: Henry Moseley, who discovered..., 105 Figure 86: Glenn Seaborg, discoverer of the transuranium.... 4 Figure 5: Aristotle..., Photograph courtesy of the Kunsthistorisches Museum, Vienna, Austria; 5 Figure 6: The Phonic Solids, as appears in The Canzbr-idge Guide to the Material World, published by Cambridge University Press NY.The following figures appeared in Torchbearers of Chemist~y,published by Academic Press, San Diego CA: 9 Figure 7: Geber..., 25 Figure 19: Georg Stahl..., 27 Figure 22: Joseph Priestley..., 28 Figure 25: Henry Cavendish, 35 Figure 33: Johann Glauber, who introduced the use ..., 41 Figure 37: Sir Humphry Davy, 42 Figure 39: Joseph Black, who elucidated the true nature..., 47 Figure 41 : Bernard Palissy, 48 Figure 43: Friedrich Wohler, who isolated aluminum, 50 Figure 47: Louis-Nicolas Vauquelin, who discovered chromium, 54 Figure 49: William Wollaston, discoverer of palladium and rhodium, 61 Figure 54: Lothar Meyer, who shared the honor..., 69 Figure 59: Andreas Marggraf, who recognized alumina..., 70 Figure 61: Robert Bunsen, best known ..., 70 Figure 62: Gustav Kirchoff, who with ..., 74 Figure 66: Lecoq de Bosibaudran, who discovered gallium, samarium..., 83 Figure 72: Sir WilIiam Crooks, who shared..., 87 Figurc 73 : Martin Klaproth, the first professor of chemistry..., 87 Figure 34: Antoine-Henri Becquerel, who discovered radioactivity.... The following figures appeared in Alchemy: Tlw Medieval Alche~nistsaarzd their- Royal Art, published by International Booksellers and Publishers, Copenhagen: 9 Figure 8: Saturn disgorging the philosopher's stone..., 10 Figure 9: Alchemists in the laboratory, in their quest for gold, 11 Figure 11: The alchemists established themselves.... 10 Figure 10: The Discovery of Phosphorus, reprinted from Special Collection of Fisher Scientific Company, Pittsburgh PA; 12 Figure 12: Charlemagne..., Hulton-Deutsch Collection, London; 12 Figure 13: Roger Bacon, as it appears in Chatrist~yfor Cl~nrrgirtg Tintw, courtesy of Prentice-Hall ColIege Archives. The following figures appeared in De Re Metal/ica, published by Dover Publications NY: 16 Figure 15: Smelting mercury ore..., 17 Figure 16: Smelting lead ore..., 17 Figure 17: Bellow, from Agricola's ..., 17 Figure 18: Mining practices, from Agricola's .... The following figures appeared in A Histoq?of Clwniistly, published by Macmillan, Hampshire: 26 Figure 21: Methods of preparation of "phlogisticated air"..., 27 Figure 23: Scheele's apparatus..., 27 Figure 24: C. W. Scheele, codiscoverer of oxygen..., 28 Figure 26: Cavendish's apparatus for collecting inflammable air ..., 29 Figure 28: Lavoisier's apparatus wherein hydrogen and oxygen..., 30 Figure 29: Lavoisier's apparatus for the decomposition..., 35 Figure 32: Paracelsus, the bombastic alchemist, 36 Figure 34: Glauber's "Iron Man," which was used ..., 42 Figure 38: The voltaic pile used to develop..., 97 Figure 81: Moseley's X-ray data ..., 99 Figure 83: Niels Bohr, who adopted Planck's quantum.... 29 Figure 27: Antoine and Madame Lavoisier..., Granger Collection, New York; 43 Figure 40: Michaelangelo's statue of David... and 47 Figure 42: Quartz crystal..., as they appear in Cltenzistr?~,published by Prentice-Hal1 Inc., Upper Saddle River NJ; 49 Figure 44: Charles Hall, who developed the commercial..., Photo courtesy of ALCOA; 59 Figure 50 John Dalton, the founder..., The Granger Collection, New York; 59 Figure 51: John Dalton's symbol for the elements, as it appeared in The Canrbr-idge Guide to the Material World, published by Cambridge University Press, New York NY; 60 Figure 52: Jons Jacob Berzelius,Photograph courtes of Gary J. Shulfer and C. Marvin Lang; 61 Figure 53: Dmitri Mendefeev, who devised the periodic table..., as it appears in Chemistry: The Central Scie~m,published by Library of Congress. The following figures appearedin Annaleit der Physik:79 Figure 70: Ramsay's apparatus for isolating argon from the atmosphere, 69 Figure60: The flame spectroscope, invented by .... 88 Figure 75: Marie Sklodowska Curie, who with her husband..., Photograph courtesy of Culver Pictures; 109 Figure 87: Lise Meitner, codiscoverer of fission..., as it appears in Scientific American, New York. PREFACE

or the past two decades, theauthor has In this collection notonly have the ele- assembled a "Living Periodic Tableof ments 1-92 been assembled, but alsomineral F the Chemical:Elements," a collectionof samplesfrom which the original elementswere all of the elements throughuranium (atomic discovered. For example, a sample of pitch- numbers 1-92). In this exhibit samples of all blende fmm theJoachirnstahl mine in Bohemia these elementshave been acquired, and have (present Czech Republic)represents radium, been the foundationof an American Chemical because Marie and Pierre Curie isolated this Society Tourconducted by the author during element from material derived from thisfam- the past six years. Authentic specimens of ous mine; "black magnetic sand"(ilmenite, these elements 1-92 FeTiO,) from Corn- include not only the , wall, England, stands familiarelements such for titanium, since the as silver, sulfur, gold, Reverend William but also the lesser Gregor produced his known elements such reddish titanium calx as iridium, hafnium, , from this gritty dark the rare earths, etc., material. This entire and even contain the display of the ele- "difficult" ones such ments and the mineral as technetium and sources is on exhibit promethium. In a few -rJat the University of instances, where the ' ' North Texas, Denton, element is transient, Texas. such as francium (with Figure 1.Catastrophe! The Hindenberg,a During the evo- GennanZeppelin, explodes and burnswhile a half-life of only 22 landingat Lakehurst,New Jersey, onMay 6, lution of this ACS minutes!), a specimen 1937. The Hindenberg used hydrogenas its Tour series, it became of pitchblende is dis- buoyantgas, insteadof the inenhelium. clear that each presen- played with the assur- Hydrogen,the first elementin he Periodic tation paralleled a ance that "an atom" Table with an atomicnumber of 1,was chapter in a standard discoveredduring the 1700s. Helium, the second resides somewherein element,was not discovereduntil the next chemistry text. For the mineral; otherwise cenhuy.Although Germany kmw helium was example, Sir Humphry authentic samplesare much safer, the U.S. helda virtualmonopoly on Davy's account of the included for all these the supplyof helium.Was it sabotageor a electrolysis of metals elements. The original naturaldisaster? The most modemtheory is furnished a foundation presentedon page 86. intent was to include for electrochemistry some of the transuranium elements, particu- and corrosion; the critical experiments on hy- larly neptunium, plutonium,and americium, drogen, oxygen,and nitrogen during the latter but federal andstate regulations forbidpublic part of the 1700s bring into play the behavior display. of gases. The sheer volume of the material presented, its applicability to modem chem- products can be obtained by the reader at the istry presentations, and the difficulty of website: copious note-taking by the audience made it h~p:llm.jenn~rshall.com/ clear that an accompanying manual was rediscovery.htm needed. This book is the result of that demand. A final question dealt with the "iconicw In developing a historical account, the Periodic Table (backcover). Should we question arose - how much detail and include icons for the transfermium elements, referencing should be included? Since a history which now are extending beyond 114, and involves real people, how much description (according to the promises of researchers in should be included for each person, and should the U.S.and Europe) will soon reach further? this detail be inserted in the running text or at Since we considered our Periodic Table a the end of the manual? We opted for the latter "living" table, and since the purpose of these choice; a compilation of scientists with a brief icons was to help the student with a visual description could be referred to at the reader's " hookw for elements and their applications, discretion. The question also came to mind - we opted not to include elements with such a since each chapter could be associated with a short life. However, in "Walking Tour of the current topic, should this connection be Elements" a Periodic Table is presented which deliberately made with modem scientific includes icons for all named elements (through explanations and amplification? We viewed 109). Also, we include all known elements (1) this to be beyond the scope of the present on the inside back cover of this book, where a edition of "Discovery of the Elements. standard Periodic Table is presented, and(2) However, an accompanying CD has been on page 113, where the latest version of the developed by the authors - "Walking Tour of Periodic Table is presented which includes the the Elements" - which pictorially explores known chemistry of the superheavy elements. fascinating additional facts about the elements The author weIcomes dl comments, andreviews the role of spectroscopy and other suggestions, and corrections. These remarks properties in the discovery of the elements. can be directed to: Dr. James L. Marshall, "Walking Tour of the Elements" includes Department of Chemistry, Box 305070, hundreds of colored photographs, including University of North Texas, Denton, Texas those of authentic samples of the elements and 76203; Email [email protected]. the minerals from which each was discovered. A further project is "Rediscovery of the Elements," where actual visits to the original Note: All temperatures given in this sites of discovery are described. A series of book are given in degrees Celsius. articles is appearing on this project, and in a few years a complete CD and accompanying book will be available. These descriptions include visits to mines, laboratories, museums, universities, monuments, plaques, and include specific information (including GPS latitude1 longitude coordinates) so that others may find the sites. Further information on these projects and instructions on how to obtain available TABLE OF CONTENTS Preface ...... i Index of Elements ...... v Index of Scientists ...... vii Introduction...... 1 Chapter 1. The Ancients (prehistoric900 A.D.)...... 3 Chapter 2 . The Alchemists (500-1700) ...... 9 Chapter 3 . The Miners (1 500-1 800) ...... 15 Chapter 4 . Lavoisier and Phlogiston (1 750-1 800) ...... 25 Chapter 5. Halogens from Salts (1740-1890) ...... 35 Chapter 6 . Humphry Davy and the Voltaic Pile (1 800-1 855) ...... 41 Chapter 7 . Using Davy's Metals (1800- 1890) ...... 47 Chapter 8. Platinum and the Noble Metals (1740-1850) ...... 53 Chapter 9 . Mendeleev's Periodic Table (1 870-1 890) ...... 59 Chapter 10. The Bunsen Burner Shows Its Colors (1860-1 863) ...... 69 Chapter 1 1. The Rare Earths (1 800-19 10) ...... 73 Chapter 12. The Inert Gases (1 894-1898) ...... 81 Chapter 13. Radioactive Elements (1890- 1920) ...... 87 Chapter 14. Moseley and Atomic Numbers (19 10-1 925) ...... 97 Chapter 15. The Artificial Elements (1935-present) ...... 103 The latest Periodic Table ...... 113 Epilogue ...... 115 Biographical Sketches ...... 117 Abundances of Elements in the Earth's Crust and Ocean, and in Meteorites ...... 133 Atomic and Mass Numbers ...... 137

INDEX OF ELEMENTS

ELE~~ PAGE

Actinirrtn. + + ...... 95 Hdium ...... 84

AJunimm.. + + . + ...... + ...+ + + ... 50 Holmium...... 79 herkiurn ...... + . + + ...... 807 Hydrop ...... 33

Antimoq . + ...... + ...... 13 Indium...... 72 Argon ....+...... +....85 Iodine ...... 39

Arsenic ...+ ..+ ...... + ...- 13 Iridium ...... - ST

Ast~etine+ .. +...... + ...... 95 Iron ...... 7 Barium ...... +...... 46 Kqpton ...... 85

B~keliurn...... + ...... I08 bnihanum ...... +..+...... 76

Fktyllium...... + . + ...... 51 bmdum...... 1OX

Bismuth...... + . + + ...... + .. 14 ~~ ...... T hhium...... +...... 109 Lithium ...... 44 Bomn ...... +.+.+...... 41 htdiuna ...... 79

Brohne ...... + . + . + ...... 39 Magn~iurn...... 45

Cadmium ...... + . + ...... 20 Manganese ...... Ig

Calcium...... + . + ...... 45 Meitneriutn ...... 209 CaIiPomium ...+ . + ...... + . 108 Mede!euiam ...... 108 ICarban ...... ,.+.+...... 8 Mmmy ...... 6

Cerium ...... + .-+ ,.,....".. 75 Mdybcnum ...... 22

Cesium ...... + ...... + . + 71 Wmdymiurn...... 77

Chlorine ...... + ...... + 38 Nmn ...... 85

Chromium ...... + ..+ ...... 20 Ncprunium...... 107

Cobalt .. + + ..+ ...... 17 Nickel ...... 18

Copper . + + . + + ...... + .... 6 Niobium ...... 19

Gu~urn..+.++..+...... +.+ 108 Nitrogen ...... 32

Duhiurn + + . + + ...... + . + . + . + I03 Nobelium...... $08

Dysprosium ...... + ...... f 8 Osmj~m...... 57

Einsteinium . + + ...... + . + 108 Ox5"gm ...... 33

Erbium . + + . + +...... + - + - + ... 79 BalIadiwrn...... 56

Europium ...... + ...... 77 Phosphms ...... 13

Femiasrn ...... + ...... 108 PIatinm ...... 56 ~UQ~~E...... , ...... 38 BIutmium ...... 107 Francium+ ...... + . + . + . + ... 95 Polonium...... 94

GadoIirhm ...... + . + . + . + ... 78 Fa;assium...... 45

Gallium .+ + ...... + . + . + ... 66 frzismd~um...... 76 Gmniurn ...... + ...... 68 Protachhrm ...... 95 mcd ...+...... a. -+-+...... 5 Pmmdkum ...... 106 ETafrziurn ...... + .,..,...... 1101 Radium ...... 94

Hassium ++.+...... +.+.+.. .. 2K) Radon ...... 95 M&um ...... 202 Rhodium...... 56 Rubidium...... 71 Ruthenium...... 57 Kuthedodium ...... 108 Samarium ...... 7? Scandium ...... 68 Sleaborgium...... 109 Selcnium ...... 21 Silicon ...... 50 Silver ...... 6 Sodium ...... 4-4 Strontium ...... 46 Sdhr ...... 8 Tan~al~rn...... 19 Techehm ...... 1M TeIIutiurn...... 21 Terbium ...... 78 TAdIiurn ...... 72 Thorium ...... ,, 93 Thulium ...... 79 Tll ...... 7 Titanium ...... 23 Tungsten ...... 29 Wrmiurn ...... 93 Vanadium ...... 21 Xmon ...... 86 Ytterbium ...... 79 Ytt2.iurn ...... 22 Zinc ...... 14 Zirmnium ...... 52 INDEX OF SCIENTISTS BIOGRAPHICALSKETCHES ARE GIVEN ON PAGES 117-132

NAME PAGE Cleve. Per Teodor ...... 74.75.78.80. 83 Abelson. Philip Hauge ...... 107 ColIet.Descotils. Hippolyte Victor ...... 57 Achard. Franz Carl ...... 53 Corson. Dale Raymond ...... 95. 104 Agricola, Georgius ...... 14- 17. 37 Coryell. CharlesDubois ...... 104. 106 Allison, Fred ...... 103 Coster. Dirk ...... 99. 101 Alter. David ...... 69 Courtois. Bernard ...... 36.37. 39 Andrada ...... see de Andrada Cranston. John Arnold ...... 89. 96 Adwedson, Johan August ...... 44. 52 Crawford. Adair ...... 46 Aristotle ...... 1.4.11. 17 Cronstedt. Axel Fredrik ...... 16.18. 73 Arkel ...... see van Arkel Crooks. Sir William ...... 64.70.82. 83 Arrhenius. Carl Axel ...... 22. 73 Curie. Marie ...... 1.86.88.89.93.94.96. Bacon. Roger ...... 12 103. 108 Balard. Antoine-Jirdrne ...... 37. 3 9 Curie. Pierre ...... 1.86.88.89.93.94.96. Becher. Johann Joachim ...... 25. 33 103.107. 108 Becquerel. Antoine-Henri .....87.88.93. 94 Dalton. John ...... 58-60 Berg. Otto ...... f 00. 102 Davy. Sir Humphry . . 1. 3 1.32.36.39.4148. Berzelius. Jons Jacob . 13.17.19. 2 I .43.44.48...... 50.52.58. 87 50752.57.58760764773.74.76.87.93 de Andrada. Jozk Bonifftcio ...... 44 Black, Joseph ...... 30.42.43.45. 58 de Boer. Jan Hedrick ...... 102 Blomstrand. Christian WilheIm ...... I9 de Boisbaudran. Lecoq . . 58.64.66.70.74.75. Boer ...... see de Boer ...... 77.79.82. 83 Bohr. Niels Henrik David ...66.99. 10 1.102. de Chamourtois. Alexandre E...... 60 108. 109 de Elhuyar. Fausto ...... 16.19.71. 73 Boisbaudran ...... see de Boisbaudran de Elhuyar. Don JuanJosk ... 16.19. 7731. Bothe. Walter ...... 103 de Fourcroy. Antoine-Franpis ....30.55. 57 Boyle. Robert ...... 1.33. 47 de Hevesy. George Charles ...... 99-1 02 Brandt. Georg ...... 16. 18 de Marignac.Jean-Charles . 19.58.68.74.75. Brauner. Bohuslav ...... 65.67.75. 77 78-79 Brownrigg. William ...... 53 de Morveau ...... 30 Bunsen. Robert Wilhelm . 44.64.69.72.74. de Ulloa, Don Antonio ...... 53. 56 83. 86 Debierne. Andre Louis ...... 88.89.93. 95 Busy .Antoine-Alexandre-Brutus ... 43. 51 Decotils. See Collet.Decotils . Casciarolo. Vincenzo ...... 43. 46 del No. Andrks...... 17.21. 71 Cavendish. Henry . 28.32.34.56.81.82. 85 DeIafontaine. Marc ...... 78 Chadwick. Sir James ...... 103 Demarcay. Eughne-Anatole ... 58.75.77.78. Chancourtois ...... see de Chancourtois 86338 Charlemagne ...... 21. 12 Democritus ...... 25

vii Deville. Henri Sainte-Claire ...... 48. 49 Lamy. Claude-Auguste ...... 70. 72 Dobereher. Johann Wolfgang ...... 59 Lavoisier. Antoine Laurent . . 2.25.29.3 0.34 Dorn, Friedrich Ernst ...... 89. 95 ... 36.39.41.42.45.47.48. 59 Draper. John W...... 83 Lawrence. Ernest Orlando .... 106.108. 109 Ekeberg. Anders Gustaf ...... 16. 19 Leonardo da Vinci ...... 32 Elhuy ar ...... see de Elhuyar Liebig. Justus von ...... 39 Fajans. Kaisimir ...... 89. 96 Linck, Johann Heinrich ...... 18 Fleck, Sir Alexander ...... 89. 96 Lockyer. Sir Norman ...... 82-84 Flerov. Georgij Nikolaevitch ...... 107 Lomonosov. Mikhail Vasilyevich ...... 33 Fourcroy . See de Fourcroy . Mackenzie. Kenneth Ross ...... 95.104 Fraunhofer. Joseph ...... 69 Macquer. Pierre-Joseph ...... 5 Gadolin. Johan ...... 17.22.73.76. 78 Marclcwald. Willy ...... 94 Gahn. Johan Gottlieb ...... 16.18. 46 Marggrd. Andreas Sigismund . . 4 1.44.46.50. Gay.Lussac. Louis-Joseph ...... 473 1 58. 69 Geber ...... 1.9. 11 Marignac ...... see de Marignac Ghiorso. Albert ...... 105.107. 108 Marinsky. Jacob Akiba ...... 104. 106 Giesel. Friedrich Otto ...... 95 Matthiessen, Augustus ...... 44 Glauber. Johann Rudolph ...... 35.36. 40 McMillan. Edwin Mattison ...... 107 Glendenin, Lawrence Elgin ...... 104. 106 Meitner. Lise ...... 89.95. 109 Grnelin. Leopold ...... 21 Mendeleev. Dimitri Ivanovich . . 2.61.66.68. Gohring. Otto H ...... 89. 96 ...... 88.97.101. 108 Gregor. Reverend WilIiam ...... 17. 23 Meyer. Julius Lothar ...... 664 1. Grosse. Aristid Victor von ...... 96 Moissan, Henri ...... 37. 38 Hahn. Otto ...... 89.95.108. 109 Morveau . See de Morveau . Hd1. Charles Martin ...... 48.49. 5 1 Mosander. Carl Gustav ...... 73-79 Hare. Robert ...... 53 Moseley. Henry GwynJeffreys 66.75.9 7.102 Hatchett. Charles ...... 16. 19 Newlands. John Alexander Reina ...... 61 Haiiy. Rend-Just ...... 49-5 1 Nilson. Lars Fredrik ...... 23.64.68.74. 75 Hkroult. Paul-Louis-Toussaint ...... 49 Noddack, Walter Karl Friedrich 100.102. 103 Hevesy ...... see de Hevesy Noddack, Ida Eva Tacke ..... 100.102. 103 Hisinger. Wilhelm ...... 73.75. 76 Occam, William of Occam ...... 36 Hjelm. Peter Jacob ...... 22 Orsted. Hans Christian ...... 48. 51 Hornberg. Wilhelm ...... 14.47. 5 1 Osann. Gottfied Wilhelm ...... 55.57. 58 Hope. Thomas Charles ...... 43 Ostwald. Wilhelm ...... 89 Hopkins. B . Smith ...... 80. 103 Palissy. Bernard ...... 47 Janssen. Pierre-Jules-CCsar ...... 82. 84 Paracelsus ...... 35 Joliot. Jean-FrkdCric ...... 103. 104 Peligot. Eughe ...... 87.93. 96 I Joliot.Curie. Irine ...... 1 03. 104 Perey. Maguerite Catherine ...... 95. 104 I Kirchhoff, Gustav Robert ...69-7 1.74.83. 86 Perrier. Carlo ...... 106 Klaproth. Martin Heinrich . . 22.23.50.52.73. Pliny the Elder ...... 6.8.10. 14 76.87.93. 96 Pott. Johann Heinrich ...... 22 Klaus. Karl Karlovich ...... 55. 58 Priestley. Joseph ...... 27.33.53. 58 Weigh,. Lord ...... 8 1.82. 85 Ramsay. Sir William ...... 8 1.86.89. 95 Reich. Ferdinand ...... 70.72. 86 Richter. Hieronymus Theodor .... 70.72. 86 Roscoe. Sir Henry Enfield ...... 21 . Rose. Heinrich ...... 119 6. Rumford. Count Rumford ...... 332 1. Rutherford. Ernest ...... 89.95.99.103. 108 Rutherford. Daniel ...... 26.27.32. 58 Samarski. Vasilii E...... 77 Schadel. Matthias ...... I07 Scheele. Carl WilheIm . . 8.17.19.22.24.27. 32 ...... 33.36.38.43.46.58. 73 Schmidt. Gerhardt Carl ...... 93 Seaborg. Glenn T .... 105.107.108.109. 111 Sefstrom. Nils Gabriel ...... 17. 2 1.74. 76 Segrk. Emilio Gino ...... 95.104. 106 Smith. J . Lawrence ...... 78. 79 Sniadecki. Jedrzej Andrei ...... 5537 Soddy. Frederick ...... 89.95. 96 Spedding. Frank Harold ...... 75. 104 Stahl. Georg Ernst 14.2529.32.34.36. 4 1. 44 Stromeyer. Friedrich ...... 1206. Strutt. John William . See Raleigh . Sylvius. Francis (de le Boe) ...... 40 Tacke. See Noddack . Talbot. William Henry Fox ...... 69 Tennant. Smithson ...... 8.55.57. 58 Thenard. Louis-Jacques ...... 4731 Thompson. Benjamin . See RumFord . Travers. Morris William ...... 84-86 Urbain. Georges ....74.75.79.80.98.99. 10 1 van Arkel. Anton Eduard ...... 102 Vauquelin. Nicolas-Louis 16.20.44.49.52.55. 57. 58 von Reichenstein. Miiller ...... 17. 2221. von Laue. Max ...... 97 Watson. Sir William ...... 53 Weigel. Fritz ...... 106 Welsbach. Baron Auer von . . 74.75.77.80. 94 Winkler. Clemens Alexander ...64.68.71. 83 Wijhler. Friedrich ...... 2 1.22.48.49.5 1. 74 Wollaston. William Hyde... 19.54.56.58. 102

INTRODUCTION

or over five millenniathe mysterious progenitor of this theory was the Arabian transmutation of substances into new alchemist Geber. A thousand years ago he Fones - the enigmatic metamorphosisof explained that mercury could contribute sand and clay into glass and pottery, the "fluidity," and sulfbr "combustibility"; later mutation of larvae into flies, the basic riddle alchemists added salt, which would confer of life itself - suggested to the human mind "fixity." that deep-seated principles were responsible. Robert Boyle (Fig. 2), best known for Beginning with recordedhistory, the ancient his "Boyle's Law," in the 1600s discussedin Egyptians weredeeply preoccupied with life "The Sceptical Chymist" the standards by and death and sought answers through which a substance couldbe adjudged as an medications,pharmaceutical preparations, and element. He realized that Aristotle's four incantations. elements and the alchemists' three principles The ancient Greekswere could not be correct, because the first to address the question they were never proven to of what these principlesmight compose, nor could they be be. Water was the obvious extracted from, any other sub- basic essence, and Aristotle stances. He expounded: expanded the Greek philo- "I now mean by Ele- sophy to encompassa obscure ments, as those Chyrnists that mixture of four elements - speak plainest do by their fire, earth, water, and air - as Principles, certain Primitive being responsible for the and Simple, or perfectly unrnin- makeup of dl materialsof the gled bodies; which not being earth. As late as 1777, scien- made up of any other bodies, tific texts embracedthese four or of one another, are the elements, eventhough a over- Ingredients ofwhich all those whelming body of evidence call'd perfectly mixt Bodies Fiyre2. Roben Boyle, the first pointed out many contra- scientistto anuEleme,.n areimmediately compounded, dictions. It was taking thou- and into which they are ulti- sands of years for mankind to evolve his mately resolved: now whether there be any thinking from Principles - which were one such body to be constantly met with in all, ethereal notions describingthe perceptionsof and each, of those that are said to be this material world - to Elements- real, Elemented bodies, is the thing I now concrete basic stuff of this universe. question." The alchemists, who devoted untold In other words, if something was an grueling hours to transmutemetals into gold, element, then it must be proven by experiment believed that in addition to the four Aristo- to be separable as basic material which could telian elements, two principlesgave rise to all not reduced to anymore fundamental stuff. natural substances: mercuryand sulfur. The Since this decisive experimentwas sorely lacking, the "chymist" had no recourse but to which had not been yet prepared in the rely on the old theories. He was still stumbling elemental form were also elements. Lavoisier over the basic flaw - he could not abandon had peeked beyond the dining room into the the outmoded concept that elements were kitchen. Aristotelian principles reflecting essences Lavoisier's insight openedthe cupboard immediately manifest to the eye and other doors, out of which tumbled a myriad of senses. He had merely renamed the old wondrousoils, sugars, and spices. Excitement principles - the Aristotelian "hotness" had grew in the scientific communityas, one by simply evolved to alchemical "combus- one, new condiments were discovered pell- tibility." me11 in this pantry. By the middle of the The truth was much more subtle- and nineteenth centuryit was recognized that the surprisingly simple. True elements were cabinetwas even organized in tidyshelves and commonly ingredientsto worldly materials. bins, and soon Mendeleev was even predicting Only rarely did an element present itself in new flavoringsnot yet tasted or dreamed of! simple forrn in nature - such as gold. It was By the early twentieth century, ninety- like trying to identi@ the flour, sugar, salt, two continuouscubicles had recognized, each lard, and eggs that went into the baking of a with an identified staple, and the scientistshad cake from the smells emanatingfrom the final cooked up thousands of new culinary formu- concoction, oftenwhen one had never seen lations. But the cuisine did not stop there! The these original ingredients! Morecommonly, an nuclear chemistsynthesized newmakings, new element wasin combined forrn in nature, and racks were built in the pantry, and eventually the extraction of these material elements the list of condiments expanded toover one eluded the scientist. The modem recognition hundred. of element had to await a true genius who This, then, is the story of how that could wonder about the original recipeof the kitchen was explored. . . . Cosmic Baker. The giant step in this evolution of thought - from philosophical Principleto materialistic Element - was made by Lavoisier, whoin his Treatise of 1789 realized that since water was manufactured by the combinationof "inflammablegas" (hydrogen) and "vital airn (oxygen), then water must be a compound. From this remarkable intuition all else followed. Lavoisierlisted 31 materids which he proposed - correctly - were the true elements, including sulfur, iron,carbon, copper, molybdenum,etc. Recognizing that "inflammable airw and *vital air" were elements, he dubbed themwith the names by which we know them today. He even recognized that "radical muriatique" (chlorine), "radical fluorique" (fluorine)and others 1. THE ANCIENTS (prehistoric times400 A.D.)

he Story of the Elements beginswith was so important that the anthropologists Stone Age Man, who had discovered differentiate the "Stone Age" from the Thow to prepare tools out of wood, subsequent "Bronze Age"and "Iron Age." bone, and rocks. He discovered that wood was Seven metals were known to the ancients good for preparingpliable implements,such as - gold, copper, tin, lead, silver, iron, and shafts and spears. Bone was excellentfor fine mercury. The first metal to be discoveredwas instruments suchas needles. Rocks could be probably gold, because of its beauty and its used for kitchen utensils (forexample bowls, resistance to corrosion, and was adopted for jewelry and ornaments. The first metal of practical use was copper, perhaps 10,000 B.C., which could be beaten into tools and ornaments. Elemental copper was occasionally found in the form of nuggets, and later (roughly 5000 B.C.) could be smelted from ores. About 3000 B.C., it was found that when copper was mixed with tina harder, more durable metal could be formed -

Fiye3. Homo erectus,about 1 million years ago, used stone tools. typically from rough igneous stones), and for took and weapons (such as scrapers and spearheads, usually flint). These materials were effective but all suffered from their tendency to splinteror break - they were all brittle. Man eventuallystumbled uponmetals which had unique properties - they were simultaneously malleableand strong - they used could be for tools and weapons, could be Figure 4. Hermes Trismegistos,the prepared under heat, and were not brittle. Egyptiangod of wisdomand the "inventorof Well over ten thousandyears ago metals all sciences." were adoptedby Man. The ancients recognized bronze. However, tin was originally scarce, that metals were very special and they and tin sources were sought out and attributed these metalswith special magical developed. Lead was soon discoveredas a properties and spirits. The discoveryof metals softer and heavier metal, it could be used as weights, water pipes, writing tablets, and Iron - Mars, the God of War coins. Silver was usually in combined form, Tin - Jupiter, the Supreme God and for a while was actually more expensive hod - Saturn, the God of Old Age and than gold until effective smelting methods Heavy Dullness were discovered. The discovery of iron was The Greeks, with their insatiable delayed because of its corrosion and the curiosity and drive for reason and logic, difficulty of smelting it. About1500 B.C., the attempted toexplain the universe in terms of beginning of the Iron Age, the Hittites "Principles." It was obvious to them thatthe developed effective procedures for extracting most common and important "principle" - iron. Mercury was easilyobtained from its ore which is found in all lakes and oceans, which -- - by mere heating - sometimes mercury "sweatn could be seen on cinnabar. Nevertheless,it was more casually mentioned in ancient literaturesince it not utilized in tools and implements; it was used in more esoteric applications, suchas "medicines. " The Old Testamentmentions six metals. As early as about 1200 B. C. (Numbers31:22) reference is made to firing gold, silver,bronze (copper), iron, tin, and lead. In Ezekiel 27: 12- 13, dated about 600 B.C., Spain is mentioned as a rich source of silver, iron,tin, and lead; and Greece is described as a provider of bronze. Ancient civilization, which had devel- .... - -.; oped a sophisticatedtechnology of materials, Figure5. Aristotle, the Greek philosopher whodefined the "four elements. " attributed Gods as being responsiblefor the I special propertiesof metals. Since there were falls out of the sky, whichforms on our brow seven metals known to the ancients,and since in hot weather, and which we mustdrink to there were seven heavenly bodies, it was survive - is water. Hence, water was apparent that each of these heavenly bodies recognizedas the first element. was associatedwith one of these metals. Since Aristotle, who codified mostof the each of these heavenly bodies wasa God with ancient information which was embraced by a distinct temperament,they found that each of the educatedpersons of the world for hundreds these elementswas clearly connected with one of years, even intothe Renaissance,stated that of these personalities: there were four elements - not only water, Gold - the Sun, or SoI, with his golden but also fire, earth, and air. He reasoned that radiance these four principles could explain all Silver- the Moon or Luna, with her soft materials we see. These four elementscould light blend in variousproportions to give rise toany I Quicksilver - Mercury, the rapid property one could want: water with its Messengerof the Gods wetness and coolness, earth with its dryness Copper- Venus, with her beauty and coolness, fire with its dryness and its hotness, and air with its wetness and its nothing has been ever ultimately produced but hotness, could produce all the rocks, wood, some one, or more, of these four substances, organisms,etc., that we observe in the world. according to the nature of the decomposed The ancient Greeks,with their penchant bodies. for harmony and mathematics, fbrther ascribed "These substances, although reputed each of these "Principlesnor "Elements" with simple, may possibly not be so, and may even one of the regularpolyhedrons, known as the result from the union of several other more "Platonic solids." Hence, earthwas a chunky simple substances:but as experience teaches us cube, air was a multifaceted octahedron,fire nothing on this subject, we may without was a pointy tetrahedron, and water was a inconvenience, and we ought to consider, in smooth icosahedron.The remaining Platonic chemistry, fire, air, water, and earth, as solid, the dodecahedron, represented the simple bodies; becausethey really act as such universe or the "cosmos." in all chemical operations." Modem chemistry could not develop until these ancient philosophiesand superstitions of principles, essences, and spirits were replaced by more practical schemes.But these old thoughts could not be abandoned until they were thoroughlytried out in red- world situations (i.e., by experimentation). This exhaustiveexamination was performedby the alchemistsand belongs in the next chapter.

Fiye6. The Platonicsolids. Gold The view that the earth was composed of these four elementspersisted into the 18th Au 79 century. Indeed, in a leadingencycIopedia of [Anglo-Saxongold, L. aunun] the day - under "Element" in A Dictionary of Known to ancients Chemistry,by P. J. Macquer, published in 1064"; 12g2808"; sp vr 19.3 1777 - the following entryis made: Gold artifactsare known from all ancient "Those bodies are called by chemists cultures. A major quest for millenniahas been elements, which are so simple, that they can- the search for the philosopher's stone, the not be by any known method bedecomposed, method by which base metals can be or even altered; and which also enter as prin- transmuted into gold. To alchemists the ciples, or constituent parts, into the combin- symbol of gold was the sun. ation of other bodies, which are therefore Gold, the most beautifid metal, has been called compound bodies. known and valued since ancient times. In bulk "The bodies in which this simplicityhas gold has the familiaryellow color, but when been observed are fire, air, water, and the finely divided may be dark. Gold is the most purest earth; for by the most completeand malleable and ductile of all metals - 1 gram accurate analyses which have been made, can be beaten to a one-square meter sheet, where the gold is 50 nm (50 x lo9 m) thick. Gold is soft and is usually alloyed to give it Copper hardness. It is an excellent conductor of electricity and heat. Unaffected by air and [L. cupnun,Cyprus] reagents, it can be used as connector contacts. Prehistoric It has been used in coinage, and is used in 1083"; hp2567"; 8.96 jewelry, decoration, dental work and for Copper artifacts date back for ten plating. Gold can be dissolved by aqua regia thousand years. Alloys of copper - brass and - 3: 1 hydrochloric acid:nitric acid. bronze - are sometimeshistorically confused with copper. To the alchemistscopper was the symbol of Venus. Copper is an excellent conductor of Silver electricity (second only to silver); hence, the Ag 47 electrical industry is one of the greatest uses of [Anglo-Saxon siolfir, L. argentwn] this element. The alloys of copper - brass Known since ancient times (copper and zinc) and bronze (copper and tin) 961.9"; hp2212"; so_pr10.50 have been known since historic times and are Silver has been known since ancient still important. The sulfate (CuSO,, blue times. It rarely occurs uncombined; in ancient vitriol) i; used asan agricultural poisonand as Egypt it was more expensive than gold. The analgicide. Fehling's solution (copper tartrate) art of refining silver soon was deveIoped; is used in analytical chemistry as a test for Isaiah described the process by adding a base sugar. metal which was oxidized, leaving a regulus of metallic silver. To the alchemists silver was the symbol of Diana (the Moon). Silver is a little harder than gold, and is Mercury extremely ductileand malleable. Silver has the Hg 80 highest electricaland thermal conductivity of [Planet Mercury, Gr. hydrargym, liquid all metals. It is stable in air, but tarnishes in silver] the presence of sulfur compounds (to form Known to ancients black Ag,S). Sterling silver (92.5% silver) is -38.8"; hg 356.7"; 13.55 used in jewelry and silverware. Silver is Mercury was known to the ancient extremely importantin photography; is used in Chinese and Egyptians, and Pliny describes its dental alloys, solderingand brazing alloys, and preparation. Mercury was the alchemist arc-resistant electrical contacts. Silver is the symbol for the planet Mercury. To the best reflector of light known, but can tarnish alchemists, mercury (the principle of fluidity) and loses its reflectance. Silver iodide has been and sulfur (the principle of combustibility) used in seeding ciouds to produce rain. Silver were responsible for the evolution of all has been used in coinage for millennia - old metals. A continuous questfor the alchemists silver dollars are 90% silver and 10% copper. was the conversion of silver, mercury, and other metals into gold. With the true understanding of the elements, it was concluded that transmutation intogold by fire and flask was impossible. Iron Mercury, also known as quicksilver, is Fe 26 the only common metal which is liquid at [Anglo-Saxon,iron, L. fermm] ordinary temperatures, and has the lowest Prehistoric melting point of all the metallic elements. 1535";hp 2750"; 7.87 Mercury is a poor conductor ofheat, but a fair Iron articles and implements have been conductor of electricity - and thus can be fashioned for perhaps five millennia. Iron is used in mercury switches. Mercury forms extensively mentioned in the Bible. To the alloys ("amalgams") easily with many metals. alchemistsiron was the symbol of Mars. It is used extensively in jaboratory instru- Iron - used in the productionof steels- ments, such as thermometers, barometers,and is the cheapest, most abundant, most usefbl, and diffusion pumps. Itis used in mercury-vapor most importantof all metals. The pure metal lamps. Mercury fulminate,Hg(ONC),, is a itself is utilized sparingly;usually iron is alloyed detonator in explosives. with carbon or other metals. The core of the earth is largely composed of iron. Iron is a critical component in life, appearing in hemoglobin as the red pigment and the Lead coordinating agentfor oxygen. Pb 82 [Anglo-Saxonlead, L. plumbum] Known to the ancients 327.5";hp 1740"; 11.35 Tin Lead is mentioned in the Old Testament. Sn 50 Lead ores are common in nature, and are [Anglo-Saxontin, L. stannum] easily smelted. The Romans used lead for Known to the ancients plumbing, writing tablets, coins,and cooking 243.0"; hp2270"; 7.31 utensils (which caused lead poisoning). Lead Tin wasknown to the ancients, who used pipes fashioned by the Romans2000 years ago it in bronze. The Romans distinguished still hnction. To the alchemists, lead was the "plumburn album" (tin) from "plumbum oldest metal, associated with Saturn. The nigrum" (lead), and mentioned tin's use as a "phiIosopher's stone" was sought by the coating for copper vessels. The alchemists alchemists to convert lead and other base associated tin with Jupiter. Tin disheshave metals to gold. been used in Europe for hundredsof years. Lead is principally used in storage Tin was mined by the Incas and later by the batteries. It is also used in ammunition, Spaniardsin Bolivia. plumbing, lead tetraethyl, and X-ray radiation Alloys of tin are quite important, shields. Lead oxide is used in crystal glass and including solders (tin-lead), pewter (tin- flint glass. Lead is a cumulativepoison and antimony), and bronze (copper-tin). Tin- poses a health hazard, notably in older outdoor plating over steel cans provide" tin cans." white paints. burned. In 1985 another form of carbon was found in the soot of electrically evaporated Sulfur graphite. In this new form, carbon atoms form S 16 C, molecular clusters shaped like soccer balls. [L. sulphurium] This molecular form is called "buckrninster- Known to the ancients fullerenewafter the designer of the geodesic (rhombic) 112.8", (monoclinic) 119.0"; dome. It is possible to place another atom l+g444.7"; inside a "buckyball," leading to unique ~~gf(rhombic) 2.07, (monoclinic) 1.96 properties. Sulhr is known in the Bible as Diamond is one of the hardest substances brimstone. The ancient Greeks used burning known, while graphite is one of the softest. sulfur as a fumigant. Pliny described in detail Carbon is the base of organic compounds and the Italian and Sicilian deposits during the is found in more than a million different Roman Empire, and described sulfur's compounds. Important compounds include medicinal purposes, bleaching of cloth, sulhr carbon dioxide, methane, and carbonates. matches, and lamp wicks. Sulhr was Carbon-14, with a half-life of 5730 years, is incorporated into gunpowder in the Middle used to date wood and archeologicd speci- Ages. mens. Sulfur occurs in elemental form and in combination (as sulfides and sulfates) in nature. This element is exemplary of a In ancient and medieval hys graphite nonmetal, which does not conduct electricity was confused with lead (Fb)and moiybdenife or heat, does not have a metallic luster, and WoSJ - all beinggrqy, sop, and slippery. All crumbles or shatters easily. Sulfur is used to three were commonly given the collecfivename manufacture gunpowder, vulcanized rubber, of '~lumbago.'' fie firsfperson to distinguish suIfiric acid, andpaper. Sulfur is essential for clearly among these different nibstunces was life - as a minor constituent of proteins and Scheele in 1779. skeletal mineds. It was not recognized until the the late I700s that charcoal and diamond were related chemically, when Wisierin 1784 showed that either diamond or charcoal cozrld be burned to Carbon give the same product, carbon dioxide. Nevertheless, it was not yet recognized that C 6 diamond and charcoal were forms of the same [L.carbo, charcoal] material; instead, it was believed by some thuf Prehistoric graphite was "partially oxidized" carbon. Not 3550"; hg (sublimes) 3367"; uniil 1796 did Smithson Tennant find that g~er(graph) - 2.0, (dim) 3.1-3.5 carbon and diamond were the same material by Three forms of carbon - diamonds, demonstrating that equal amounts of carbon graphite, and charcoal - have been known in and diamond burn to give equal amounts of nature for millennia, but only two hundred carbon dioxide. years ago were they recognized as common material, ali yielding carbon dioxide when 2. THE ALCHEMISTS

uring the Dark Ages, the bright light were continuouslychanging from one from to of chemistry was sustained by the another. Deep in the earth, they believed, the Arabians. The classical Greek texts in metals slowly evolved to a higher form. Lead mathematics, astronomy, and medicine had would slowly transform into iron, then into been translated into Arabian by about 850 copper, thence to silver, and finally to gold. A.D. A huge amountof experimentaldata was Indeed, if one dug into the ground and found being accumulated notonly for metals, but a baser metal, such as iron, then it was natural also for acidsand bases, salts, organics, and to remark, "The metal was dug up too soon. other chemicals. Foremostof the Arabian Cover it up and let it continueto grow and chemists was Geber (Fig. 7), who raised mature." Unfortunately, the earth took too experimental science to a new level with long to change iron into gold, and only a extensive documentationand new textbooks. future generation could benefit from this This Arabian wealth of information slowly transformation. migrated into Europe. Known by its Arabian Since all substancescontained principles, name - "a1 kimiya," i.e., "the chemistry"- if one could only understand and direct these practitioners of this art becameknown as principles, then he could produce more "alchemists." precious materials. If only one could discover a catalyst to rapidly effect this transformation, it would be glorious indeed! Such a catalyst, called "the philosopher's stone" (Fig. 8), would enableone to produce gold in large quantities. Thus wasborn the "Alchemist," who spent thousandsof toiling hourstrying to

Figure 7. Geber (Abu MusaJabir ibn Hayym),the most famous of the Arabianalchemists.

The Medieval alchemists were accumula- ting a wealth of informationon the mysteries Figure 8. Saturn disgorging the of " transmutational"changes, and were mak- philosopher's stone on Mt. Helicon in Greece.Mt. Helicon in centralGreece was ing attemptsto interpret their observationsand the legendaryabode of the Musesand was their hopes. They observedthat substances sacred lo Apollo. unlockthese secrets of the philosopher's stone been mentioned inthe Bible as "stibic stone," (Fig 9). used as a black mascara. Zinc was used in The Alchemists developeda theoretical medical preparations, known primarily in basis for their work and findings. They calamine and also recognized as an ingredient believed that all metals were formed fromtwo in brass. Bismuth was discovered more principles - mercury and sulphur. The recently; as a heavy, malleable metal, it was mercury, with its essentiaiproperty of fluidity used in metallic wood-work trim; and with its and fusibility, gave riseto the malleability of low melting point it could be used in casting metals. The sulphur, with its essential property printing type. Arsenic had been known in the farm of its compounds since ancient days; Pliny the Elder described its use in yellow cosmetics and medicines (eventhough it is a ~oison!1.

Figure 9. Alchemistsin the Iaboratory. in the quest for gold. of combustibility, contributed body and calcination (rusting). It made sense that the most perfect of metals - gold - was produced from mercury and sulphur, because the sulphur would impart the yellow color to the mercury to produce the beautiful lustrous metal. If only the Alchemist could combine mercury and sulphur in the correct pro- Fiyre 10. "TheDiscovery of Phosphorus." portions, with the philosopher's stoneas a catalyst, he would produce gold in prodigious The alchemistswere responsiblefor the quantities. genesisof modern chemistry. They developed As the Alchemiststoiled countlesshours as a subculturein medieval Christianity, and over the furnace, they stumbled upon several unwittinglypaved the way for this science by new substances, whichtoday we recognizeas making threedistinct contributions:(1) exper- elements, but at the time were characterized as imentationitself, involving the ancient chem- strange blendsof the principlesof fire, earth, ical processes of distillation, precipitation, water, and air, andof mercury, sulphur,and decrepitation, calcining,etc.; (2) a basis of salt. Phosphorus wasisolated fromurine, and Greek logic and harmony, providingthe faith was named as suchbecause it literallyglowed that logic and reasoningcould arrive at a final in the dark (Fig. 10). Antimony was answer, even when the truth was not intui- recognized as a new substance;it actually had tively obvious;and (3) a faith in God, with the Figure 11.The alchemistsestablished themselvesas a subculturein medieval Christianity,blending the glorificationof God, Greek tradition,and experimentation.The true chemical philosopherworshiped his Godthrough prayer, studyof His writtenword, and study of His Creation- Nature- in the chemical laboratory. befief that He had created a harmonious world the Catholic Church, who viewed these with Perfection as the ultimate goal and which, inquiriesas a threat to its ultimate authority. excepting miracles, bctioned through orderly The successive waves of translations from the processes. Chemistry, as with all the sciences, Arabic and Greek spread across Europe and depended upon these three factors for its threatened the Christian philosophy unless development (Fig. 11). Christendom could construct a counterphiloso- The Moslem culture had invaded Spain, P~Y. and the ideas of Geber (experimentation) and Meanwhile, Charlemagne (Fig. 12) had of Aristotle (logic) invaded the minds of the directed cathedrals and monasteries to establish Medieval Europeans, much to the dismay of schools where clergy and laity might learn to read and write, and later to study grammar, that science should be a necessary part of music, and arithmetic. Thisidea spread and education, since science reveals the gloryof developed untiI Universities were common, the Creator in His Creation and His Works. teaching a liberals arts curriculum of the Most importantly, Bacon introduced the inductivemahod to science. Othershad argued that the only real proof is deductive

Figure 12. Charlemagne,the founder of the cathedral schoolsthat evolved into universities. Fiyre 13. Roger Bacon, who foundedthe inductivemethod. "triviumn - grammar, rhetoric, and logic - and then the "quadrivium" - arithmetic, priori: Effects must follow from the Cause, geometry, music, and astronomy. Since the and since the Cause is known from the culture of the church was responsiblefor the Scriptures andfrom Aristotelian knowledge, University, and since knowledge threatened one can merely argue from them - the the faith of the church, the role of the specific must follow from the general.Bacon, University became to establish the Biblical on the other hand, pled that science must use Truth by using Aristotelian logic and experimentas its method, since it cannot reach knowledge. its conclusionsuntil explained mathematically. A common teaching technique of the In other words, the descriptionof natural law University was by means of disputtzlions must be induced from many examples - the among the teachers,students, and visitors. A general can follow from the specific. He question was stated and argued by Biblical graphically illustrated his point by stating, quotations and Aristotelian certitudes,and the "Themost rigorous conclusionsof logic leave negativewas given and defended in kind. This us uncertain until they are confirmed by back-and-forth discussion formed debates, experience; onlywhen we are singed are we sharpened the mind, and expanded the mental convinced that afire is hot and can burn us." arena that could be explored. This breakthrough led the way for the From this culture came the most famous experimental method, the foundation of of the Medieval scientists,Roger Bacon (Fig. modern science. Finally philosophy could 13). Although he reducedscience and philoso- break the shacklesof Aristotelian philosophy, phy to the role of servants to theology, never- which held that at1could be deduced from theless he appealed to the Pope and the Clergy previous writingsand observations with no need for further inquiry. The "officialn form of phosphates, andin living systems in explanations couldnow be questioned. protoplasm (in nucleicacids) and bones (as But while all of this philosophizingwas hydroxyapatite). White phosphorusignites takingplace, everyday life mustcarry on. That spontaneouslyin the air and is stored under is, technologywas evolving. Thatnew topic water, butred phosphorusis safer. Phosphates will be the basis of the next chapter. are extensivelyused as fertilizersin agriculture and horticulture. Monosodium phosphateis used in baking powder. Phosphorusis used in the productionof bronze andother metals. Phosphorus Trisodium phosphateis used as a cleaning agent, water softener, andcorrosion inhibitor. P 15 30.97376 [Gr. phosphoros,light bearing] Discovered1669 Arsenic a (white) 280";3~ (white) 1.82, As 33 74.9216 (red) 2.20 [Gr. arsenikon,yellow orpiment] Hennig Brand, a seventeenth century Known to ancients;element discovered1250 alchemistand physicianof Hamburg, learned 42 817" (28 atm);wblimes how to extract from urine a waxy, white 613"; 5.73 substance thatglowed in the dark.Soon the Arsenic was known to the ancientsas secretrecipe was out, and many chemistswere orpiment,a yellow pigment(arsenic sulfide). preparingthe mysterioussubstance, studying Albert the Great was probably the first to it, and displayingit in public and in regal isolate theelement, by heatingorpiment with court. Soonphosphorus wasfound not only in soap (ca. 1250). urine, but in other animal and vegetable Arsenic is found in nature commonly matter; in the 1700sbones were discoveredto associated with sulfidesof metals. When consist of "lime saturatedwith phosphoric heated, arsenicforms arsenic oxide P AS,^,), acid." Before the true nature of combustion which smells like garlic. Arsenic and its was understood, phosphorus was consideredan compounds are highly poisonous and have "escape of phlogiston." It was observed that been used as agriculturalinsecticides. Arsenic white phosphorus, whenexposed to light, is is used in the semiconductor industry. transformed into red phosphorus.Berzelius showed the two forms were modifications of the same element. In the 1800sphosphorus was usedin matches. Antimony Another lesscommon form of phosphorus - "black phosphorus"- is known, [Gr. anti-monos, not alone] which resembles graphite.The molecular Knownto ancients; structureof white phosphorusis individual element knownto alchemists tetrahedraof P, units; that of red phosphorus m~ 630.7"; 1950";sp ~r 6.69 is cross-linked tetrahedra; thatof black Antimonywas known to the ancientsin phosphorus is hexagonalsheets (likegraphite). the formof its sulfide,a black eyepaint used Phosphorusis found in mineralsin the in the characteristicEgyptian porkitswith cat-like eyes. In the Bible, Jezebel paints her soaps, textiles, etc. Zinc sulfide is used to face with "stibic stonen (antimony sulfide). It make luminous dials, X-ray and TV screens, is not clear whether the ancients knew metallic and fluorescentlights. antimony, but the alchemists were very fami- - liar with it - Georgius Agricola mentionsan Bismuth alloy with tin in printer's type. Bi 83 208.9804 In nature, antimony can be found with [Ger. Weisse Masse, white mass] sulfides and arsenides. Antimony is used in the Known in the Middle Ages semiconductorindustry. As an alloying agent, 271.3"; hp 1560"; 9.75 antimony is used to harden lead. Pewter is a Bismuth dates back to the 1400s, when it tin alloyed usually with antimony. was used astrim in woodwork. In 1450 it was employed in casting type for printing presses. Agricola recognid bismuth, which was being Zinc procured from mines near Schneeberg, Ger- Zn 30 65.39 many, as a metal separate from lead - at this [Ger. Zink] time most miners believed there were three Known to ancients in brass; discoveredas kinds of lead (tin, lead, and bismuth), and that metal in the Middle Ages bismuth had advanced the furthest in the 419.6"; hg 907"; 7.13 transmutation of lead into silver. By the early Zinc compounds have been used for 1700s bismuth was recognized as a specific centuries for medicinal purposes - Pliny metal. described how they were used for healing With a low melting point, bismuth is wounds and sore eyes. In the Middle Ages used in low-melting alloys for safeey devices in Marco Polo reported tutty (zinc oxide) fire detection and extinguishing systems. manufacture in Persia. Brass, an alloy of Bismuth is the most diamagnetic of all the copper and zinc, has been produced for metals, has a Iower thermal conductivity centuries. Probably zinc has been prepared in (except mercury), and has the highest Hall isolation from time to time, but the first effect (increase in electtical resistance in a authentic report of elemental zinc was in the magnetic field). sixteenth century, when zinc was imported from China. Soon zinc was being smelted in Europe. In 1695 Wilhelm Homberg guessed, The Medieval sourcefor zinc was mostly and in 1735 Johann and Georg Stahl calamine, a general term for zinc carbonates confirmed, thatcalamine consisted of an "ore and silicutes. In dern times, when this of zinc." By the end of the 1700s zinc was "us&l" ore of zinc was no longer readily recognized as an element. available, zinc sulfide (sphalerite)has been Zinc is extensively used in alloys: brass, exploited. Typical impurities in zinc include nickel, silver (industrial and restaurant kitchen gallium, indium, and cadmium, @en are sinks), solder, die castings, etc. Zinc is plated prepared as byproducts of zinc manufacture. onto iron to "galvanizen and to prevent In ancient times elemental zinc was not corrosion. Zinc oxide (white)is used in paints, observed because it is volatile and evaporates rubber products, cosmetics,pharmaceuticals, in a hot fire. 3. THE MINERS (1500-1800 A.D.)

'odern science dependsupon both Different methodologies were used for theory (that is, basic science) and different metalsand different ores. Mercury,

t technology (practical applications). for example,was produced by merely heating Likewise, progress during the Middle Ages the ores (Fig. 15). Indeed, cinnabarand other depended uponboth theory and technology. As mercury ores commonly show a metallic the Alchemists were plodding along with their "sweat" in nature. Other metals,such as lead, secret recipesand cryptic writings, theprac- required a more elaboratescheme of roasting tical miners were advancing their techniques litharge and other lead ores (Fig. 16). Iron, the for extracting the metals from the ores for most difficultof the ancient metalsto smelt, spears, plowshares,and ornaments. required special reducingconditions and a A marvelous volumewas produced by hotter temperature(Fig. 17). Georgius Agricola(Fig. 14) toward the end of this period. This work,entitled De Re Metal- lic~("About Metal") described the complete production of metals from ores, including prospecting, mining, smelting, and assaying. This written manuscriptincludes spectacular woodcuts which meticulously describethe methods of the time. Origindly written in Latin, De Re Metallica was translated into English by Herbert Hoover, who before his Presidency had earlier been a mining engineer, and his wife Lou Henry Hoover.

Figure 15. Smelting mercuryore, from Agricola'sDe Re Metallica. Mercurywas relativelyeasy to procure -just heat the ore.

The mines of these times were dark and spooky places. IIluminationwas providedby flameand was meager. Everycomer of the mine was shadowy and hid mischievous gnomes and goblins who caused havoc with the mining and smelting process.In church the Figure 14. Georgius Agricola, who wrote De miners and their families would pray for safety Re Metdim. and protection from theseevil spirits. Brandt in 1737 was able to isolate a oxide), which was used to decolorize glass. metal as an impurity from Scandinavianores The de Elhuyar brothers in their Basquesem- and was able to show that thisnew substance inary in Spain isolated tungsten in wolframite was the cause of the difficulty in smelting . (iron tungstate), named after the "tung stens" copper and iron ores. He named this metal or "heavy stones" of Scandinavia. Charles after the German"Koboldn - gnome- and Hatchett, an English chemist, discovered thereby discoveredcobalt (Fig. 18). Cobalt niobium from a sample of columbite (calcium had actuallybeen known for hundredsof years niobate) discovered in New England. This as a blue compound, used in glass - known metal, originally named "columbite" was today as "cobalt glass." Cronsted,a Swedish confused with the very chemically similar mineralogist, likewiseinvestigated the *green tantalum (discovered by Ekeberg) in subse- ores" of the Scandinavian minesand wasable quent years and was formally named by to isolate another of these troublesome Heinrich Rose as "niobium." Vauquelin, a impurities. He named the new metal "nickel" French mineralogist, discovered chromiumin after the German"Cupfernickel," another one "red lead from Siberia" (crocoite, lead chro- of the meddling "devils" in the smelting mate), an unusual mineral found in the gold process ("nickel" means"Satann). mines of the Ural Mountains. Stromeyer, a One by one several other metals were discovered during this period. Gahn discovered manganesein pyiolusite(manganese

Figure 17. Bellows,from Agricola'sDe Re Metallim.These bellows, from the other side of the wall, furnished the hearthwith the necessaryair to smeIttin, copper, and Figure16. Smeltinglead ore, from iron. Sometimesthe bellowswere operated Agricola'sDe Re Metullic. by a water wheel. German pharmacist, was curious about a tical to del No's erythronium. Telluriumand yellow impurity ina medical zinc (calamine) selenium were isolated from the dregs of preparation and found cadmium. And& del sulfuric acid vats, by von Reichenstein and Rio, a professor of mineralogy at the School Berzelius, respectively. Thesetwo elements were later traced to the pyrites(sulfides) of the ores of more common metals. Yttrium was isolated by Gadolin from a strange black ore (gadolinite, a rare earth calcium silicate) from Ytterby, Sweden. Molybdenumwas extracted from mofybdenite(molybdenum sulfide) by Scheele by the reaction of the ore with nitric acid, then charcoal. Titaniumwas discovered in "magnetic black sandn in Cornwall, England by Reverend Gregor. Slowly the list of metals was growing, and each was recognized asunique. Somebodyhad to make senseout of this hodgepodge of metals! Technology had far outstripped theory. Obviouslythe alchemist's doctrine of a mingling of mercury and sulfur was woefully inadequateto explain the riches spewing from the mines and hillsides of Sweden, England, Transylvania, Mexico,and the U.S. Meanwhile, the Universities were questioningthe basic tenets of Aristotle. The time was ripe for a profound change in philosophy and a recantation of two thousand years of pedagogical dogma. Thenext chapter tells this story.

Figure 18. Mining practices, from Agricola's De Re Metallim. Deep in the mine, illumit~ationwas feeble. andmischievous gnomes lurked around every corner. From the Germanword for "gnome"- Cobalt Kobold- originatedthe name for cobdt. Co 27 58.9332 of Mines in Mexico, isolated a new metal he [Ger. Kobold, goblin] named "erythronium" in "brown lead from Ores known for centuries,metal isolated Zimaph, Mexico" (vanadinite,lead vanadate 1735 chloride). Owing to Old World arrogance,del gg 1495";JZIZ 2870"; 8.9 Rio was refused recognition of this metal, In the 1400s an annoying mineral was which was "rediscovered" by Sefstriim in found in the mines of Saxony and Bohemia. Sweden. Sefstr6m named the metal *vana- This mineral was difficult to remove during dium," but recognized his material was iden- the smelting, and arsenic in it was unhealthy. This mineral was called "cobalt" from the to metallic nickel. Cronstedt immediately German Kobold meaning subterranean gnome, claimed the new metal to be an element, but which according to local myth caused miners the elemental nature of nickel was doubted by mischief and endless trouble. By the 1500s it some until the latter 1700s, because of con- was realized that this mineral could produce fusing mixes of ores in nature. beautifd blue glass. Georg Brandt prepared a Nickel is used in stainless steels and blue pigment from an ore from Riddarthytta, other corrosion-resistant alloys such as Sweden, and by 1735 he had prepared the Hastelloy; copper-nickel alloys are used in metal. The similarity of iron, nickel, copper, desalination plants. NickeI is now the pre- and cobalt ores, and the confusing mix of their dominant metal in coinage. It is used in armor reduced metals and arsenic made it difficult to plate and burglar-proof safes and vaults. establish conclusively the elementd nature of Nickel plating is common in consumer steel cobalt until the late 1700s. products, such as office supplies. Nickel Cobalt, when alloyed with iron and powder is used as a catalyst in hydrogenating nickel, produces Alnico, an alloy of high vegetable oils. Nickel, as the second most magnetic strength. Salts of cobalt have been common constituent in iron meteorites, is used used since historic times to produce the blue as a criterion for identifLing them. colors in porcelain and glass. The transition CoCli6H20(pink) + CoCl, (blue) + 6H,O is utilized in invisible ink and in humidity indi- Manganese cators. Mn 25 54.9380 [L.magnes, magnet] Oxide known for centuries, Nickel metal isolated 1774 Ni 28 58.693 1244"; & 1962"; 7.30 [Ger. Nickel, Satan] Pyrolusite had been used for centuries to Ore known for centuries, metal isolated 1751 color glass a beautiful violet. The mineral was 1453"; Ihg2732"; 8.90 known by the names "black magnesia" and The history of nickel is similar to that of "manganese." Johan Gahn in 1774 prepared cobalt. In Germany a reddish-brown ore with metdlic manganese by heating pyrolusite green spots was used to color glass green. The (manganese oxide) and charcoal. miners called the mineral Kupfemickel, mean- Manganese improves the manufacturing ing copper devil or "fake copper." J. H. Linck qualities and the strength of steel. The dioxide stated in 1726 that since the ore gives green is used in dry cells, and decolorizes green solutions, it must be a cobalt ore containing glass (caused iron impurities). Manganese is copper (even though no one had ever extracted the trace impurity producing the lavender coIor from it!). The miners sometimes described the of amethyst. Permanganate (MnOil)is an mineral as "cobalt which has lost its soul." excellent oxidizing agent, used in analytical Axel Cronstedt in 1751 investigated a mineral chemistry and in medicine. Manganesenodules hma mine at Los, Hiilsingland, Sweden. He recently discovered on the floor of the ocean calcined (oxidized) the greenish coating of this may be a future rich source of this element. mineral and reduced the product with charcoal Winthropof Massachusetts."The sampleof Tungsten (Wolfram) "columbite,"as it became known,yielded in W 74 183.84 1801 a brown precipitate which Hatchett [Swed. tung sten, heavy stone, Ger. identified as a derivativeof a new metal, Wolfrahm,wolf froth] dubbedcolumbium. Hatchettnever succeeded Discovered 1781,metal isolated1783 in isolatingthe elementalform; in 1864C. W. 3410;hg 5660"; 19.3 Blomstrandreduced the chloride withhydro- In 1781 Scheeledissolved a mineralfrom gen to producethe metal. Attemptsto find the Sweden called tungsten (now known as original source of the "Columbianmineral" scheelite)in nitric acid anddiscovered an acid were unsuccessful, and some Continental similarto molybdicacid, which he called terra chemists (Berzelius) even doubted the ponderosamolybdctrzata (tungstic acid). Two authenticityof theAmerican origin.The name years later the de Elhuyarbrothers extracted colu&iurn was used by the English and frorn wolfram(wolframite) the sameacid and Americans, although Berzelius opposed this prepared a metallic sample by heating with use and preferred niobium (which had been charcoal.The source of the word " Wolfrahm" given by Heinrich Rose). The International is derivedfrorn the interferenceof the ore with Unionof Pure and AppliedChemistry in 1950 the smelting of tin - it supposedly "de- o fficiaIly adopted the name "niobium," voured" thetin. althoughit is still known amongmetallurgists Tungsten has thehighest meltingpoint and U.S.producers as "columbium,"with the and the lowest vapor pressure of all metals, symbol "Cb." and at temperaturesabove 1650" the highest Niobium has been extensivelyused in tensile strength. It is used as filaments in advanced framesystems in aviationand space electric lamps and electronand television technologies.It is used in arc-weldingrods for tubes; for electrical contacts in automobile stainless steel. distributors; and X-ray targets and heating elements. Tungstenis used in high-speedtool steels andHastelIoy, and tungstencarbide in Tantalum metal-working activities.The coefficientof Ta 73 180.9479 expansion is thesame as bornsilicateglass, and [Gr. T'talos,bearer, sufferer] is used for glass-to-metal seals. Discovered1802 2996"; hg 5425"; 16.65 In 1802 Anders Ekeberg, Professorof Niobium Uppsala, isolated a new metal from both Nb 41 92.9064 yttrotantalitecollected at Ytterby, Sweden, and [Niobe,daughter of Tantalus] tantalite from Kimito, Abo, Finland. He Discovered1801, metal isolated1864 named the new metaltantalum because of the tantalizingefforts in isolating it. Wollaston 2468"; hg 4742"; sr>_rrr8.57 CharlesHatchett, a wealthy chemist in thoughtniobium and tantalumwere identical, London, whilerearranging specimensat Brit- but laterwork by Heinrich Rose (1846) and ish Museum discovereda curiousheavy black Jean-Charlesde Marignac(1866), on thebasis stone, labeled as an "iron ore from Mr. of the niobicand tantalicacids, proved the two metals were indeed separate and distinct. green color, and ruby its red color. The yellow Tantalum occurs with niobium in nature, and dichromates (Cra2) are used as oxidizing is separated from this element with difficulty. agents in analytical chemistry and in tanning Tantalum is virtually immune to chemical leather. Chromium compounds are used in the attackat ordinary temperatures and is excellent textile industry as mordants, and for anodizing in anti-corrosive applications. The melting aluminum (fonning a very thin protective point is exceeded only by tungsten and oxidized coating). rhenium. Tantalum can be drawn into a fine wire, and was originally used in electric light bulbs until tungsten replaced it; now tantalum Cadmium is used as a filament for evaporating metals. Cd 48 112.41 Most of tantalum's use is in electronic [L. cudrrzia, calamine] components, mainly capacitors. The second Discovered 18 17 most common use is tantalum carbide, used in 320.9"; hp765"; 8.65 cutting tools and dies. Alloys with tungsten, Friedrich Stromeyer, inspector-general of titanium, and niobium have high melting apothecaries in Hanover, on an inspection trip points and high strength, and are used in the in 1817 noticed that a certain medical aircraft and missile industry, nuclear reactors, preparation contained zinc carbonate instead of and chemical process equipment - such as a the specified zinc oxide. Upon questioning, the "patch" in a boiler perforation. Since tantalum director of the pharmaceutical firm explained is not irritating to the body, it is used in that when the carbonate was calcined to surgical equipment and artificial joints in the produce the oxide, instead of remaining white, body. Tantalum oxide is used in high refrac- it assumed a displeasing ocher color; hence, tive glass for camera lenses. this step was omitted. Iron, the immediate suspect for the yellow contamination, was shown to be absent. Curious, Stromeyer Chromium dissolved the zinc carbonate in ammonium carbonate; the residue he ignited to a brown [Gr. chroma, color] oxide. Upon reaction with charcoal, a bIuish Discovered 1797, metal isolated 1798 gray metal was obtained. He named the 1857"; & 2672"; 7.20 element cadmium, from cadmium fornucum NicolmLouis Vauquelin studied red lead ("furnace calamine"). from Siberia (crocoite) and concluded it Cadmium occurs most often in zinc ores, contained a new element (1797). The and is similar to zinc in many respects - for following year he obtained the metal by example, as a protective electroplated coating reacting the oxide with charcoal. Because of on steel agents, its greatest use. It is used in the many colors of its compounds, he called it bearing alloys with low coefficients of friction chromium. andresistance to fatigue. It is used in solders Chromium is used, with iron and nickel, and Ni-Cd batteries. Its compounds are used in to manufacture stainless steels. As chrome blue and green phosphors in television tubes, plating, it can be used to produce a hard, and as a yellow pigment (CDs). Vincent van beautifid surface. Chromium gives emerald its Gogh used yellow cadmium paints. Vanadium Selenium V 23 50.9415 Se 34 78.96 Discovered 1801, metal isolated 1869 [Gr. Selene, moon] [Scandinavian goddess,Vanadis] Discovered 1817 mp 1890";hg 3380"; sp 6-11 217"; & 685";ur 4.79 Andres Manuel del No, a native of In 1817 Berzelius observed ared mass at Madrid who took a position at the School of the bottom of a vat of a sulfuric acid plant at Mines in Mexico, studied a specimen of Falun Mine, Sweden. Heoriginally thoughthe "brown lead from Zimaphnand concluded it had prepared tellurium (discovered 35 years contained a new element, which he named earlier), but the strong odor of "decaying "erythronium" (1801). The initial report of his radishes" aroused his suspicion. Carehl discovery wasdoubted in Europe, because the experiments resulted in the preparation ofa element's propertieswere similar to thoseof new element, recognizedto be the cause ofthe recently discovered chromium; and a fult strange odor, which he named selenium in description of his research was lost in a analogy with tellurium. In 1820 Gmelin in shipwreck. Losingconfidence in his discovery, Bohemia prepared pure selenium from fuming del Rio dropped his claims,and his sample in sulfuric acid and demonstrated the element the Berlin Museumfiir Naturkunde (Natural originally came frombits of pyrite. History Museum) was accompanied by the Selenium manifestsphotovoltaic action lengthy descriptor writtenby the naturalist (light is converted directly intoelectricity) and Alexander Humboldt: "Brownlead ore from photoconductive action (electrical resistance the veins of Zimaph. Lead chromate. M. del decreases with increasedillumination). Hence, Rfo thought he had a new metal in it, later he selenium is used in photocells, exposure redized it was ordinary chromium." In 1831 meters, and solar cells; the drum in photocopy Nils Sefstr6m discovered a new element in machines is coated with selenium. Selenium iron from the Taberg mine in Smaand, can convert alternating current (ac)to direct Sweden,whichhe called vanadium.WohIer the current(dc) and is used in rectifiers. Selenium same year analyzed the "brown lead from occurs in some soils in sufficient amountsto Zimaph" and concluded that delRfo had been poison animals feeding on plants. correct in his original assessment,and that his erythronium was identical to Sefstrom's vanadium. The mineral is now knownas Tellurium vanadinite. Roscoe in 1869 prepared metallic Te 52 127.60 vanadium by reducing vanadium trichloride [L. tellus, earth] with hydrogen. Discovered 1782 Most of the vanadium is used as an 449.5"; 989.8"; sr>.rrr6.24 additive in rust resistant and tool steels - a In the 1700s certain gold ores in tough alloy utilized in morplate, axle rods, Transylvania proved difficult to assay and piston rods, andaxles. Vanadium is also used were considered "unripe gold" (an alchemist in superconductivemagnets. Vanadium pent- term for impure gold). Miiller von Reich- oxide is used in ceramicsand as a catalyst. enstein, a mining commissionerin this region, after three yearsof testing concluded that the famousfor its strange and intriguing rare earth ores contained an unknown new metal which minerals. In 1828 WBhler obtained the imparted a red color to sulfuric acid, and metallic element by reducing the yttrium which reprecipitated as a black solid when chloride withpotassium. diluted with water (1782). He published in an Since yttrium behaves Iike a rare earth, obscure journal, of which only two volumes it is sometimes considered "outof place" in were printed (Physikalische Arbeiten der the Periodic Table, the other rare earths being eintrdchtigenFreunde in Wen - "Workit1 the fiften elements 57-71 (lanthanum-lute- physics by harmonious friends in fiemu"). tium). Thelargest use of yttrium is in the form Desiring verification of a new metal, he of its oxide, which is used to make YVO,- submitted a sample to Klaproth, the leading europium and Y,O,-europium phosphors to analytical chemist of Germany. In 1798 produce the red color in television. Yttrium Klaprothreported the new discovery before the oxide is also used to produce yttrium-iron Academy of Sciences in Berlin, naming the garnets, excellentmicrowave filtersand trans- element tellurium and giving credit for the mitters of acoustic energy. Yttrium is also discovery to Miiller von Reichenstein. used in laser systems and as a catalyst for Telluriumis used as a basic ingredientin ethylene polymerization. blasting caps and in ceramics. It improvesthe machinabilityof copper and stainlesssteel, and added to lead it decreasesthe corrosiveaction Molybdenum of sulfuric acid. Mo 42 95.94 [Gr. molybdos, lead] Ores known for centuries, element Yttrium recognized 1778, metal isolated 1781 Y 39 88.9059 mp 2617"; hp4612"; 10.22 [Ytterby, village in Sweden] Molybdtin, or molybdma, was the name Discoverv: oxide 1794; crudemetal 1828; for a soft, black graphite-like mineral now pure metal 1953 known as "molybdenite" (MoSJ. To the 1522"; hp 3338"; so 4-47 German-speaking it was known as Wasserbley The chemistry of the rare earthsbegan (' water-leadn). Although Johann Pott recog- with gadolinitein 1787 (then called yfferbife), nized it was not a lead compound, he conhsed when Lieutenant Karl Axel Arrhenius, it with graphite (Reissbley), and believed it Swedish mineralogist,collected a black rock at consisted of lime, iron, and sulfuric acid. In a fluorspar mine near Ytterby,Sweden, just 1778 Scheele investigated the mineral and north of Stockholm. The mineral "resembled demonstrated that graphite and rnolybd~na coal" and because of its weight was suspected were two entirely different substances- nitric to contain tungsten. Johan Gadolin, at the acid had no effect on graphite, but reacted University of Abo, Finland, investigated the with molybdaena to produce a white solid he mineral in 1794 and was successful in called molybdic acid. He suggested it separating a "white earth," which was named contained a new metal, and three years later yttria from the quarry where the mineral was with Peter Hjelm's furnace they fired the found. This Ytterby site was soon to become molybdic acid with charcoal to produce the metal molybdenum. for propeller shaftsand other parts of ships Molybdenum has the third highest exposed to sea water. Titaniumis as strong as melting point amongthe common elements steel, but is almost one-half as light. Star (tungsten andtantalum being 1st and 2nd). It sapphiresand rubies exhibit asterism because is a valuable alloying metal to harden and of TiO,. Titanium dioxide,as a white base, is toughen steels, and improves the strength of used in house and artist's paint - the largest steel at high temperatures. Almost all ultra- use of the element. high strength steels containmolybdenum in amounts up to 8%. Molybdenum is also a catalyst in petroleum refining. Many ores are sulfides, formed it1 hydrothemmi vents in the earth's crust. These sulfides are precipitated from aqueous solu- Titanium tions in fracture zones located in batholiths, Ti 22 47.867 huge pockets of moltetz igtieous rocks, As the [Gr. Titans, the first Sons of the Earth] batholith cools, silicates crystallize in a stan- Discovered 1791, metal isolated 1887 dard sequence starting with olivines (peridot) 1660";bg 3287"; 4.54 and feldspars and endingwish mica and Two hundred years ago Reverend quartz.Remaining is a pressure cooker aque- William Gregor gathered some black sand oussolution of sulfir, arsenic, antimony, lead, from his parish in Menachan Valley, Creed, copper, tin, and orher transitiotz metals, As the Cornwall, England. He called the substance solid batholith cools firflher and fractures, the "menachanite" (now known as ilmenite). hot solution vents upward to cooler and lower From this mineral he prepared a "reddish pressure regions, where many minerals crystal- brown calx" (1791). Meanwhile, Klaprothin lize, o$en in aquisiteforms mui lovely colors. 1795 discovereda new oxide from red schorl The most common sulJde is pyrite, FeS,, (rutile, Ti03 from Boinik, Hungary.This called such because it gives off sparks when substance,which he called "oxyd of titanium," struck, Pyrite is also known as "fool's gold, " bore a close resemblance to Gregor's, which bur it is easily distinguishedfrom gold, since it he investigated. After heanalyzed an authentic is harder and more brittle. Copperfrequently menachanite sample,he concluded they were forms bornite, C~fleS,,also known as "pea- the same, and gave credit to Gregor for the cock ore" because of its avian iridescence. discovery of the element, but retained his Cobalt is ofren found in cobaltite, CoAsS, a name of titanium. In 1887 Lars Nilson bright metallic steel-gray mked sumde. prepared the metal by reducing titanium Galena (PbS), a dark lead gray mineral, is tetrachloridewith sodium. the most common ore of lead, M%en galena Titanium is almost always found in has inclusions of acanthite, A@, it is called igneous rocks. Some rocks from the moon also "argentiferous" and is mined for the silver. showed large amountsof TiO,. Titanium has When acanthite crystals grow to observable both a low density and a high strength. It is sizes, their intricate shapes well describe the easily fashioned metallurgically, canwithstand tuune - "tlzom" in Greek. The most common extremes of temperature, and resists corrosion ore of nickel, pentalandite, (Fe,Ni).,S8,is a - thus, it is ideal for aircraft and missiles, and light bronze yellow. Molybdenite, MoS,, is the major ore of molybdenum. Molybdenite is a under an ultraviolet lamp. Scheelite can be soft, greasy black mineral that closely resem- distinguished porn the associated powellite, bles graphite (in fact, it war conzed with CaMoO,, from the latter's custard-yellow graphite unril Scheele's work). Most of these . fluorescence. Vanadiumis commonlyfound in sulfides are metallic in appearance, and are vanadinite, Pb,(VOd3Cl, a pretty red-brown either dark, silvery, or bronze. A notable mineral. Chrommrum,although forming resplen- exception is mercury - cinnabar, HgS, is a dent red crocoite crystals, PbCrO,, mostly stunning vermillion mineral. The very rare occurs in the dull black mineral chromite, greenockite, CdS, is a sulphur yellow. FeCr,O,. Opiment, As,S,, well know to the ancients, is Selenium and tellurium are found as also bright yellow. @halerile, ZnS, is the most selenides and tellurides of copper, lead, and common ore of zinc. Although white when other metals. Tellurium foms interesting pure, sphalerire ofien is hued to beautifrrl minerals with goM and silver, such as hues. A burgundy fom, ruby sphalerite "from calaverite, Au,Te,, and sylvanite, AgAuTe,. the Tri-State area (Missouri-Oklahoma- These were the principal gold ores during the Kmsos), firmished smll but critical amounts gold tush in Cripple Creek, &lorado, forming of germanium and gallium during World War stunning silvery blades and prisms. II. Cadmium also is commonly mixed with Yttrium is mainly found in rare earth sphulerite and other zinc compounds, and is a minerak, such as smrskite (see above), gado- byproduct of zinc production. linite, (Ce,La, Nd, Y)~eBe&O,,, and emen- Transition metals are also found in other ite, (Y,Ca, Ce) (Nb, Tu, Ti),O,. mese minerals forms. me most common ore of iron is the red will be seen again in Chapter f1, us a general hemutite, Fe,O,. Copper is found as the source of the rare earths. surfide (chulcopyytite, CuFeSJ, oxide (cuprite, The ancient miners had good cause to be Cu,O), and the carbonates (malachite and confised, because nickel and cobalt ores that mnte, a2(CO$,(OH., and Cu,(COJ2(OW, appeared like copper ores did indeed give them respectively), Malachite and azurite are the cause to think that gnomes were busy in their royal green and blue ores of copper. Malachite mischievous ways. Niccolite, (NiAs, also is fashioned into elegant ornaments, jewelry, knownas nickeline) is a pale copper-red color; and boxes. lin isfound as cassiterite, SnO,, a it alters with time (oxidizes) to annubergite, brownish admantine mineral. Rtanium is Ni,(AsO$2.8H20, of an apple-green color, most Pequently seen in ilmenite, FeTiO,, a This transformationfkom red to green color black spar that frequently powders into precisely mirrors the behavior of copper. ne "magnetic black sand. " Pyrolwite, MnO,, is Statue of Liberty, for example, is constructed the main ore of mcutganese, an mophous of copper but with age acquires a pretty green black mineral. Niobium and tantalum are seen patina of malachite, Cu,(CO,),(OH),. Like- in columbite/tantalite, (Fe,Mn) (Nb,Ta),O, , wise, the similar appearances of "cobalt blue " pyrochlore, (Na,&)fl,O,(oH, F)*nH,O, and ondazurite, Cu,(CO,),(ON)J, were equally samrskite, (Y,Fe, U)(M, Ta)O,, all dense, mystifying to the ancient miners. dark minerals. Tungsten is mixed with other minerals but occasionally crystallizes out as scheelite, CaWO,, a heavy, white octahedral ctystal that fluoresces a dazzling blue-white 4. LAVOISIER AND PHLOGISTON (1750-1800 A.D.)

he stage was now set for a giant leap in Lavoisier's work was founded on a the understanding of chemistry. A vast theory proposed a hundred years before his Tamount of knowledge had been time. In the 1600s Becher founded, and Stahl accumulated during the previous several elaborated (Fig. 19), the so-called phlogiston thousand years. Man understood how to theory, suggested to explain the overall process ceramics, glass, and metals. In the observations of combustion (burning), calxing previous several hundred years new (rusting), and respiration (animal breathing). compounds and acids had been discovered; the Although this theoryis nowconsidered crude technology of ceramics, glass, and metals had and far off the mark, it was one of the most advanced greatly; gunpowder had been important advances in chemistry because it discovered and utilized in peace and in allowed for the first time a theory that allowed warfare; physics had exploded with a new predictions and therefore could be tested. As understanding of the laws of motion; any modern scientist knows, the progress of electricity had been discovered; and the center science rests upon the proposal of theories that of the universe was no longer the earth, but predict and can therefore be tested, validated, the sun. However, the four basic elements refined, or discarded. were still considered to be fire, earth, water, Stahl proposed that thethree processes of and air. Since chemistry involves invisible atoms (not yet hypothesized, except briefly by the Greek Democritus), the basic understanding of chemical processes would be difficult. It would take a great genius to take that great leap from archaic thinking to a new theory of chemical processes. Ironically, this great leap involved not traditional substances - metals, sulphur, charcoal, salts and acids - but instead revolved about the investigation of the three gases nitrogen, oxygen, and hydrogen. Lavoisier, a French tax collector and part-time chemist, was able to piece together all the fragmentary information to arrive at a new view of the universe that allowed the birth of a new view of chemistry. Indeed, Lavoisier is called the Fip19. Georg ErnestStahl, who Father of Modern Chemistry. elaboratedthe phlogistontheory. combustion,calxing, and respiration together metals, such as white for antimony or black reflected Nature's managementof a universal for manganese). This calciningphenomenon principlecalled "phlogiston" (Greek"inflarn- was explained by the same process: metals mable" principle). Accordingto this theory, would release phlogiston tothe atmosphere when a material bums (combusts), phlogiston (today we know this process as "oxidation," is emanated and is released into the but remember, "oxidize"was not known as a atmosphere. One can actually "see" and word yet, because "oxygen" had not been *hearmthe release of phlogiston during, for identified). The calx could be 'rephlogisti- cad" by reaction withcharcoal to regenerate the metal. Obviously, Stahl said, charcoal was very rich in phlogiston, which made sense since charcoalcomes from plants (wood). AIthough wood and other combustible materials lost weightduring burning, metals when calcined mysteriouslygained weight. The former observationthat wood disappeared upon burning - was easily explained by simply assuming the products of burning disappearedinto the atmosphere.The gain of weight of metals, however, was more difficult to explain. Since metals gained weight when

Fiyre20. Daniel Rutherfont, the discoverer of "phlogisticatedair." i.e., nitrogen. He was an uncle of Sir WalterScott, the novelist. example, the burningof wood, as heat waves are observed and the hissing of escaping phlogiston is detected.Whereas the ancients believed thatfire ascended into the empyreurn, Stahl believed that the phlogiston combined with the mosphere. Plants then could absorb the phlogiston into their organic material to produce "phlogisticated" substanceswhich animals could then eat. As the animals respired, the foods released their phlogiston back into the atmosphere. Thuswas observed a continuous cycle, with phlogistonflowing from fires and animals into the atmosphere, where plants couldproduce "rephlogisticated" material. Meanwhile, metals were observed to Figure21. Methods of preparing "phlogisticatedairn - by calcining a metal, calcine to produce a calx (red-brown in the and combustionof a candle(upper),and by case of iron, but different colors fordifferent respirationof a mouse(below). they lost phlogiston, then it followed that (Fig. 24) were independentlyable to prepare phlogiston must havenegative weight! That is, "dephlogisticatedair. " Although Priestleyis the prediction wasmade that phlogiston had generally credited withthe discovery, Scheele anti-gravity. performed more precise experiments and "Phlogisticated" airwas first character- probably discoveredoxygen beforePriestley . ized by Daniel Rutherford (Fig. 20) (not to be Scheele delayed his reports and thuswas confused with Ernest Rutherford, who investi- "scooped." gated the structureof the atom more than a century later). Rutherford prepared"phlogisticated air" by burning a candle, calcininga metal, and by collecting the respirationgases of a mouse (Fig. 21). He showed that all of these gases behaved similarly. For example, after the mouse died in a closed container (it usually took about fifteenminutes), Rutherford showed that this "dead mouse gas" would not support the combustionof a candle nor the calcining of metal. Likewise,the air produced from a calcined metal or a burned candle Figure 23. Scheele'sapparatus for producing "Feuerluft"(oxygen). would not supporta mouse forthe fullfifteen minutes. Hence, Rutherford had shown that Scheele's apparatus is shown in Figure "Stahl was correct": The air from the three 23. He heated a calx (mercuric oxide) and processes of combustion, calcining, and collected the resulting gas in a bladder respiration wereindeed the same, and hence (balloonshad not yet been invented). He called this air must be "phlogisticatedair. " his product " FeuerIuft" (fire air). Priestley The next step was to prepare "dephlo- called his gas, produced in a similar fashion, gisticatedair." Priestley(Fig. 22) and Scheele "dephlogisticated air. " Scheele proposed a

Figure 24. C. W. Scheele,independent discovererof oxygen (whichhe called Figure 22. Joseph PriestIey,the discoverer "Feuerluft,"or "fire air"). of "dephlogisticatedair," ix., oxygen. balanced equation for the process which was have phlogiston, whichwas predicted to have consistentwith Stahl's phlogiston theory: negative weight! (Fig. 26). This trapped air was shown to be quite combustible and calx of mercury + (4 + fire air) = accordingly was termed 'inflammable air." It beat1 made perfect sensethat phlogistonitself should be so reactive. He even wrote a balanced equation to show the chemicalcombinations of all the materialsinvolved: It only remained for phlogiston itselfto be found. This discovery was made by (calx + @) + acid = Cavendish,an eccentric millionaire whoper- [metal] (calx + acid) + + formed experiments in laboratorieshe set up in r=w [ible his mansions. Shy and retiring, Cavendish air] rarely showed himseIf in public; but his lectures were brilliantand reflected extremely careful and meticulous work. Hisretiring ways were so extreme that he fired a servantwho ventured to speak with him rather than communicate by his preferred method of writing notes and shoving them under the door. He never posed for a portrait and only one quick sketch of him exists (Fig. 25).

Figure 26. Cavendish'sapparatus for collecting inflammableair (hydrogen).

It would appear that Stahl's theory of phlogiston had been fully vindicated - the equations appeared to accurately describe chemical behaviorin accordancewith Stahl's interpretation of nature. Additional cases abounded: for example, one could predictthat Figure25. HenryCavendish, the discoverer sulphur was a combination of oil of vitriol of hydrogen("inflammable air"). (sulfuricacid) and phlogiston by the following Cavendish's experimentation involved reasoning: Since liver of sulphur (potassium the addition of Mars (iron) to oil of vitriol sulfide) could be made by heating potash (sulfuric acid) to produce a gas which he (potassium hydroxide) withsulfur; and since collected in a bladder. He observed that the liver of sulphur could also be produced by bladder floated in the air, and thus he must heating vitriolated tartar (potassium sulfate) with charcoal (rich in phlogiston), then: tion, Lavoisier assembled an apparatus that contained dephlogisticated air and phlogiston (sulphur + potash) = (oil of vitriol + that could be reacted with a spark (Fig. 28). potash) + phlogiston He passed a charge through the arc and wit- nessed a mighty explosion. He had fashioned And by subtracting potash from both sides of strong glass walls towithstand the force of the the equation, we conclude that reaction. Upon carefully inspecting the contents, he observed not phlogisticated air as the sulphur = oil of vitriol + phlogiston. product but water! In every science, there has been a event Hence, it was reasoned, sulfur must be a that signaled the evolution from a primitive compound - and it was believed that quite faith to a true modern science. In biology this possibly oil of vitriol (sulfuric acid) was in event was Darwin's theory that all species fact an element. were created by natural mutation and selec- By now a student of chemistry would tion; ever since, "no thing in biology makes recognize a thread of truth throughout all of sense without evolution. " In physics perhaps these theories, observations, and conclusions, this milestone was laid by Galileo, who but would also perceive that everything observed that all objects fell at the same rate seemed to be backwards. But hindsight is and showed that all physical phenomena powerfbl, and it took a powerful genius to obeyed mathematical laws. In astronomy this figure out what was actually happening. This turning point was founded by Copemicus, who master, Lavoisier (Fig. 27), boldly made the postulated the heliocentric theory. In geology prediction: If Stahl were correct, then dephlo- it was the understanding that earthquakes were gisticated air would react with phlogiston to caused by naturalevents in Terra instead of by produce phlogisticated air. To test this predic- the rage of God; in bacteriology it was that microscopic living beings caused diseases instead of humors and evil spirits. And in chemistry it was the ~avoisier'sinsight that water was a compound, and therefore the

Figure 27. Anloine and MadameLavoisier. Antoine'swife helped him in many of his experiments aradmade records that helped Figure 28. Lavoisier's apparatuswherein him deducedthe true compound nature of hydrogenand oxygen were sparked and water, and to recognize the true elements. reactedto form water. "inflammable air" (which had been supposed could be named on this basis. Thus it became by others to be phlogiston) and the "dephlo- understood that the "fixed air" of Black was gisticated air" or "vital force" were actually actually an oxide of carbon, and the white elements. In fact, Lavoisier gave names to "ffowers of zinc" which grew from the gray these two elements, calling the first "hydro- metal was "zinc oxide." Thus, Lavoisier gen" ("water-former") and the later "oxygen" revolutionized chemistry not only by recog- ("acid-former") (Fig. 29). Hence, phosphorus nizing the true elements, but by also com- was no longer "the fatty part of urine pletely transforming the vocabulary (Fig. 30). concreted toa very combustible earth" but was The understanding that compounds were an element. With this incredible perception, composed of distinct contributions of elements Lavoisier went on to identify thirty-one also greatly simplified the great confusion substances as elements (Fig. 31, next page). Incredibly, he recognized chlorine ("muriatic radical") and fluorine ("fluoric radical") were OLD NAMES- W NAMES elemental, even though the elemental substances themselves ltad never been isolated Flowers of zinc - zinc oxide (only salts)! He continued to realize that other Liver of sulphur - potassium sulfide elements must exist from their compounds: Spirit of wine - alcohol boron (from borax and similar compounds), 6 Philosophical spirit of wine - silicon (from quartz and glass), magnesium diethyl ether (from Epsom salt), calcium (from limestone), Spiritus sulphuris volatilis Berguinii - ammonium polysulfide and aluminum (from clays) when none of - Manna mercuri mercurous chloride these elements had ever been isolated in its - Butter of antimony - antimony elemental form! This was insight of a chloride staggering degree. Salt of Mars - ferrous acetate Corrosive icy oil of tin - stannic chloride Aqua fortis - nitric acid Spiritus salus - hydrochloric acid Oil of vitrol - sulfuric acid Green, blue, white vitriol - iron, copper, zinc sulfates Sugar of lead -lead acetate Crystalli lunae - silver nitrate Sal ammoniac- ammonium chloride Figure 29. Lavoisier's apparatusfor the Jovial bezoar - antimonic acid red-hot decomposition of steam over iron. Fattypart of urine concreted to a very The gas he collected he named "hydrogen, " combustible earth phosphorus since obviously thisgas "is the generative - principle of water. * And Lmoisier did not stop there! He Figure30. Names used before 1800,and their equivalent according to the new nomenclature, went on to understand, since compounds were developed by Lavoisier in collaboration with combinations of these elements, that they Fourcroy, Berthollet, and Morveau. I LumiEre. Chaleur. Principedc la chaltur. l~hideig&. , - chaleur.

Gaz phIogiltiqu6, =!Mofet.. BaCe dc la mafete, Gaz infiammable. BaG du jpi~~flaarolablt, Soufre...... Soufre. Phofphore...... Phofphorc. Sul;pancrrJm- ptr: non mCralE- Carbone...... Charbon pur. Radicalmuriatique. Inconnu. Radical fluorlquc . Inconnu. Radicdboracique,. Inconnu. Andmoine...... htimaiae. Argent...... Ar ant. Arlcnic...... Atr mic. Bifmuth...... Bifmutb, Cobolt...... a- Cobolt. Cuivrc...... Cuivre...... Etaia, F'er. MangantTe. difibkr. Mercure...... Mercure. Molybdkne. ., .. Molybdinc...... Nickel...... Platine...... OnPiomb...... TungRene* ...... Zinc...... Terrc calcaire, chaqx...... MagnClie, bat5 du fel' d'Epfim, ...... ,Barore,tetre pefante...... At ile , tcrrtde I'alun, bare %e lklun. Siice... ,...... Terre liliceufe,terrc vitrifiable.

Figure 31. Lavoisier's elements, aspublished in his Trait6 ~kmenrairede Chimieof 1789. Lavoisier correctly identifiedthirty-om elements,and even named two of them - hydrogenand oxygen. We was able to recognizedthat several "principles"must be elements,even thoughthey had never been isolatedin the elementalform: chlorine("radical muriatique"), fluorine("radical fluorique"), boron ("radical boraciquen), calcium ("chaw," or "chalk"), magnesium,barium, aluminum,and silicon. Lavoisierincorrectly identified light ("lumibre") andheat ("calorique"); this error was correctedby Count Rumford, who manied Lavoisier's widow after he was guillotined.Interestingly. Lavoisierdid not recognizesoda and potashas coruainingelemental principles- knowingthat ammoniumwas a compound containing nitrogen,Lavoisier assumedthe chemicallysimilar sodium and potassium likewise were compoundsof nitrogen. Davy proved otherwiseby his electrolysisexperiments a scant twenty years later. also greatly simplified the great confusion created by many names for the same Nitrogen substance. For example, the "fixed air" (oxide of carbon) had been observed under various [Gr. nitron-genes,ni ter-forming] circumstances and experiments and had been Discovered 1772 cataloged by a bewildering array of different mp -209.9"; hg 195.8"; density 1.25 g/L names, including: &rial acid, Mephitic air, air For half a milIemium it has been known surabaondante, gas syhestre, mineral spirit, that air has two major constituents. Leonardo mineral elastic spirit, choke-damp, acid da Vinci himself described these two gases, crayeux (chalky acid), "the poisonous gas that one that supported flame andanimals, and the extinguishes a candle flame," "gas forming in other that did not. Scheele calIed these two cellars, especially from fermenting wine," and gases "fire air" and "vitiated air." Daniel SO on. Rutherford, uncle of Sir Walter Scott, first Interestingly, Lavoisier identified "heat" isolated nitrogen and announced its discovery and "light" as elements. At the time it was in a doctor's dissertation. In 1772 he prepared natural, because these "substances" were nitrogen by means of a mouse confined in a observed to evolve from other substances. For container of atmosphere until it suffocated. example, when a cannon was bored, "heat" After removing the "mephitic air" (carbon was released from the iron. It was left to dioxide) with caustic potash, he had remaining Count Rumford (who married Lavoisier's "noxious air" (nitrogen), which was unwhole- widow when he was guillotined during the some because it was "atmospheric air saturated French Revolution) to understand the true with phlogiston. " After Cavendish prepared nature of heat. niter (sodium nitrate) by sparking the gas in Lavoisier was a tax collector for King the presence of oxygen and caustic soda, the Louis XVI and was well versed in accounting. name nitrogett was suggested. Lavoisier (1789) He was keen on "balancing of the ledger." considered the substance an element and called This view led him to understand that in all it mote ("without life"). In German it was chemical reactions, there must be neither a net named Srickstof(choke-damp). Curiously, the gain nor a net loss. Lavoisier thus embraced elemental nature of nitrogen was questioned the concept of "The Conservation of Mass," for years - even by Sir Humphry Davy, who the basis for balancing equations. tried to decompose it in the early 1800s. The execution of Lavoisier was indeed Nitrogen is the principal constituent of tragic. Being a government employee by voca- the atmosphere (Nd.Nitrogen is important in tion, he had been caught up in political events. foods, poisons, fertilizers, and explosives. "It required but a moment to cut Nitrogen can exist in many oxidation states, off his head and perhaps a hundred giving rise to N,O, NO, NO,, N,O,, N,O,, years will not suffice to produce NH,, and others. In certain desert areas of the another like it." world nitrogen is found in the form of nitrates. - Come de Joseph- The largest consumer of nitrogen is the buis Lagrange. ammonia industry. Oxygen Hydrogen 0 8 15.9994 H 1 1.0079 [Gr. oxys-genes, acid-former] [Gr. hydro-genes, water-former] Discovered 1774 independently Discovered 1766 by Priestley and Scheele -259.3"; -252.9"; density 0.0899 g/L -mp -218.4"; Ihp-133.0"; density 1.43 g/L Hydrogen had been observed several Five centuries ago, Leonardo da Vinci times before its "discoveryn in 1766. Robert was the first to recognize that air consisted of Boyle in 1671 observed that Mars (iron) in two major components. However, the concept acid produced an "inflammable stinking that flammable materials directly reacted with smoke." In the latter 1600s, Johann J. Becher one of these atmospheric constituents was and Georg E. Stahl proposed a theory of delayed by the concept of phlogiston combustion that chemists accepted for a (t$Aoytcrtbv), formulated by Becher and Stahl hundred years. According to this theory, all in the late 1600s. They maintained phlogiston combustible materials contain a substance, was a volatile constituent of flammable matter phlogiston (~Aoyrarbv),which escapes in the released by combustion. Hence, Priestley called form of a flame while burning; a metal the gas "dephlogisticated air" that he obtained consisted of its calx (oxide) and phlogiston. in 1774 when he heated oxide of mercury to Observations of hydrogen were generally obtain the metals (i.e., he interpreted the interpreted as the release of this principle; M. phlogiston to be reuniting with the metals). V. Lomonosov (1745) reacted metals with Lavoisier, noticing that metals gained mass acids and observed an "inflammable vaporn during calcination, assertedthe gas couldn't be which "could be nothing else but phlogiston." losing anyconstituents such as "phlogiston." The first person to make a careful study of this Instead, a substance from the air was inflammable gas was Henry Cavendish, an combiningwith the metal during calcination. eccentric English millionaire (1766). He Through very careful experimentation Lav- collected hydrogen over mercury and distin- oisier unequivocally disproved the phlogiston guished it from other gases. He described the theory by defining the true nature of com- properties of hydrogen and methods of collec- bustion. He recognized the active atmospheric tion from different sources. Mistakenly, he principle as an element and named it oxyg2ne. thought hydrogen was derived from the metal Oxygen (0,) is the most common rather than from the acid. He was the first to element in the earth's crust, constituting 50% discover as an observable fact that hydrogen of the sand, clay, limestone, and igneous and oxygen can be completely converted to rocks. Oxygen is the second most common their own weight of water - from this he element in the atmosphere (0J and the most concluded that hydrogen was a compound of common element in the oceans (H,O). This phlogiston and water. (Lavoisier's quantitative element is very reactive and can combine with analysis of water was more precise). He was most elements, forming a countless number of aware of, but rejected, Lavoisier's interpre- mineral and biological compounds. It is tation of combustion. Lavoisier in his brilliant essential for respiration in plants and animals contribution (Traird ~kmentairede Chimie, andatmospheric combustion. 1789) correctly interpreted water not as an element,but as a compound,and hydrogenas A wonderful exhibit of Lavoisier's an element, and its combustionas its reaction apparatus exists in the Muske des arts et with oxygen. Cavendishcalled hydrogen the mktier (Museum of arts and measurement)on

"inflammable airn; Lavoisier gave it the - the Right Bank of the Seine. 7he exhibit modemname, hydroghe. includes some of his delicate equipment with Hydrogenis the most abundantelement which he careJisllyweighed specijic amounts of in theuniverse, although limited inquantity on hydrogen and oxygen and the spark flask the planet earth, mostly in theform of water which produced the water. l3is equipment was (H,O). Ordinarilya gas (Hd,hydrogen is con- state-of-the-art apparatus of the day, without verted to a solid metallic form under the which Lavoisier could not have quantitatively intense pressurein the core of the giant studied the basic reaction of= planets. Hydrogenis the lightestgas, but is hydrogen +oxygen 3 water. vigorously combustible,leading to tragedies Lavoisier was an unique individual who such as ZeppelinHindenburg. Hydrogenions could combine both abstract and descriptive are the activeprinciple in acids (H+).Most of chemistry to arrive at ftrndamental truths. His the commerciallyproduced hydrogen is used vocation as a tar collector trained him to in the Haber process for manufacturing qmitateand expect cottservation of mass - ammonia(3H, + N, - ZNH,). A great deal of "me ledger must balance; what goes in must hydrogen is also used in the food industry to come out; there must be no loss in either an hydrogenate oils. accountant's books or in a chemist's laboratory." His avocation as a lover of science and dreamer allowed him to rnake the leap of genius to recognize the true elements. Lavoisier's laboratory was located in Le The "French chemistry" was quickly Petit Arsenal, near the Bastille in Paris, accepted in Lavoisier's homeland but was France. Neither the Bastille, the Arsenal, or bitterly resisted in Stahl's home country of Lavoisier's laboratory still exist. Only a Gemany. Thomas Thomson of the University plaque presently enenstson the wall ofa modern of Edinburgh wasone of thejirst in the British building, Isles to embrace the uanti-phlogistictheory. " "Ici se trouvait It was many years before the chemical world 1'Hotel de la Regie des Poudres generally rejected the phlogiston theory which ou travilla et habita de 1776 b 1792 had held swayfor a hundred years. Antoinne-Laurent Lavoisier Rkgisseur des Poudres et Salpttre qui y installa son laboratoire de chimie "

"Here was located the Hotel of the regulation of (gun)powder where from1 776 to t 792 Antoine-Laurent Lavoisier worked and lived Registrar of powder and saltpeter who there established his laboratory of chemistry" 5. HALOGENS FROM SALTS

uring the age of alchemists, there was Trying to make sense out of old frequent opportunity for fraud. Many explanations, Paracelsus accepted the idea of Da trickster could exploit the greed of mercury as the principle of ksibitity and the public by perpetuating hoaxes, typically sulphur as the principle of combustibility, but the creation of gold. A notable exception to he reasoned that there must exist another the chicanery was the early sixteenth century principle of fixity and incombustibility - salt. alchemist Theophrastus Bombastus von Hohen- When these three principles are present in the heim, better known as Paracelsus (Fig. 32). human bodyin the correct proportions, health Determined to break from the superstitions of is experienced. Disease is thus caused by an the past, he promoted logicd explanations and imbalance of these three principles (and not by true cures. Far example, he explained that evil spirits). Paracelsus anticipated by several miners suffering from lung disease were centuries the three classes of compounds: afflicted with ore dust rather than being alloys (metals bonding with metals), covalent besieged by evil spirits. His most famous compounds (nonmetals bonding with non- contribution was the discovery of mercury metals), and salts (metals bonding with non- compounds, which he promoted as a cure for metals). Paracelsus analyzed metals and their syphilis which was sweeping across Europe. calxes (rusts, or oxides), and first used the These mercury compounds were used as term "reducen when a calx was reverted back effective agents until the twentieth century. to the metal.

Figure33. JohannGlauber, who imduced the useof sodium sulfate(Glauber's salt) into medicine.Glauber extensively Figure 32.Paracelsus, the bombastic investigatedthe preparationand propertiesof fchemist who put medicineon a themineral acids. scientificbasis. Johann Rudolph Glauber wasan early xide) to form a suffocating gas. Under the seventeenth century self-educated German philosophical spell of Stahl, he interpreted his chemist whomade a particularly avid study of observations as the pyrolusite extracting salts (Fig. 33). His interest in salts began when phlogiston from the acid to form "dephlo- he cured himself by drinking the water of a gisticated muriatic (marine) acid." Scheele mineral spring. He investigatedthe water and noticed that this gas bleached flowers and found a salt he called "Sal mirabile" ("won- reacted with metals. derhl salt"), named after him as "Glauber's There exists a rule in science labeled salt," or sodium sulphate. Glauber's descrip- "Occam's razor" which is commonly used to tions of acids, which were prepared from salts, make decisionswhen a choice is to be made were superb. He recountedthe preparationof between two theories. Namedafter Williamof hydrochloric acid, nitricacid, and sulphuric Occam, this tenet holds that in lieu of hard acid by several methods, some of which are evidence to the contrary, the simplesttheory used in the teaching laboratory today. should be selected. The current belief at the Hydrochloric acid - termed in his day as end of the sixteenthcentury was that oxygen "spiritus salus," or "spirit of salt" - could be existed in all acids (indeed, Lavoisier had prepared by the distillation of common salt named "oxygen" as an "acid-former"), and with oil of vitriol (sulphuricacid). Nitricacid subsequent interpretationsof this mysterious ("spiritus fortis," or "strong spirit") could substance mainIy included a composition of Iikewise be made from saltpetreand oil of oxygen and hydrochloric acid. By 1807 Sir vitriol. Oil of vitriolin turn was generated Humphry Davy chose the simplest view that fromheating wet greenvitrioI (iron sulfate)or chlorine must be elemental, and he named it alum (aluminum sulfate). These distillations (after its yellowgreencolor). Acceptance of were preparedin Glauber's own invention, the the elemental nature of chlorine wasnot "Iron Man" (Fig. 34). immediately universal, even though attempts to decompose chlorine by heating with dry charcoal were unsuccessful. However, after iodine and bromine werediscovered and were shown to be irreducible, "oxidized muriatic acid" as a term for HCI was abandoned. Iodine. The next halogen that was isolated in the elemental state was iodine- and quite by accident. Neversuspected before, iodine was produced by Bernard Courtois in 1811 when he treated seaweed with sulfuric acid. Courtoiswas involved in the production of sodium and potassiumcompounds from Figure 34. Glaukr's"Iron Man," which seaweed. This abundant commodityalong the was used to preparemineral acids. French seashore was reduced to ashes by burning and was subsequentlyleached to form Chlorine. Scheele, the codiscovererof a brine which was allowed to evaporate. First oxygen, in 1774 reacted spiritus salus (hydro- sodium chloride, and then potassium chloride, chloric acid) with pyrolusite(manganese dio- were selectively precipitated.To destroy and remove some of the undesired by-products as a flux for smelting. "Acid of fluorspar" (mainly sulfur compounds) of the mother (hydrofluoricacid), produced by the action of liquor, Courtoisadded sulfuricacid. One day sulfuric acid on fluorspar, was found to etch he added too much,and to his surprise lovely glass. Soon this method was preferred to violet clouds arosewith a chlorine-likeodor. create intricate designson glasswareover the These colored cIouds condensed on cool more time-consumingprocedure of scratching objects to form beautiful dark violet crystals with a diamond tip. with a metal-like luster.Courtois characterized During the 1700s much conhsion existed this substance,noticed it did not compose with concerning the natureof "acid of fluorspar," heat, and suspectedit was an element. Davy principally because it dissolved the glass proved its elemental nature by demonstrating containers that held it, producing a white that it could not be altered by passage over a precipitate (silicates).After it was shown that red-hot carbon filament. the acid in lead or gold-lined vessels did not Bromine. Balard, a pharmacist in produce such a white precipitate, analysisof Montpellier, France, discovered bromine. the acid could proceed without misinter- While investigating mother liquor from asalt pretation. The acid created much interest, and marsh near his home, he noticed the liquor many investigatorssuffered grievously from its become brown when treated with chlorine. He harmful effects on the body, and some even isolated this brown substance by distillation died. Nevertheless, research was pursued from potassium bromide, sulfuric acid, and relentlessly. After hydrochloric acid, hydro- manganese dioxide. Rapid progress on bro- bromic acid, and hydroiodic acid were shown mine was made, because it was recognized as to be simple (without oxygen), and that being similarto chlorine and iodine. Indeed, it chlorine, bromine, and iodine were recognized was realized that "brominefinds its place as elements, it was assumed that the acid of between chlorineand iodine," thus anticipating fluorspar was likewise a simple acid, periodic behavior of the elementsby a quarter hydrofluoricacid, and that a simple element of a century. fluorine might be produced. Since fluorine Balard wanted to name the substance must be very reactive (even more so than "muride" (after "sea") but the scientificcom- chlorine!), then electrolysis was chosenas the munity preferred "bromine" ("stench").Other method of preparation. The problem was to scientistshad isolated brominebut had missed utilize a solution that wasconductive and yet the "discovery" because they identified it as held no water - because electrolysis of an "iodine chloride." aqueous solution would merely break down Several researchers of the time also water into hydrogenand oxygen. observed bromine compounds in certain The seemingly impossibletask of the Mediterranean mollusks. Indeed,Tyrian (or electrolysis of hydrofluoricacid was finally Royal) Purple, a beautiful, expensivedye, had accomplishedby Henri Moissan in Paris (Fig. been extracted from the straight-spinedMurex 35). In 1886 he electrolyzed asolution ofdry since ancienttimes. It is now known that this potassium fluoride and anhydrous hydrogen dye is 6,6'dibromoindigo(Fig, 36, page 39). fluoride, using platinum-iridium electrodes Fluorine. Fluorine compoundshave been sealed into a platinum U-tube sealed off with used for hundredsof years; Agricoladescribed fluorspar caps, with the entire apparatus how fluorspar(calcium fluoride) couldbe used cooled to -23" (using methyl chloride as the refrigerant). At the anode a gas was produced even died. Henri Moissan prepared elemental that immediately burst silicon into flame. The fluorine itself in 1886 by electrolyzing a KF- most reactive nonmetal had finally been HFmelt chilled to -23". At the anode fluorine isolated. was produced, identified by bursting a piece of Moissan's method of electrolyzing salts silicon into flame. Since Moissan could not to form fluorine was based upon Sir Humphry use glass, which would react with fluorine, he Davy's technique developed many years before fashioned fluorite (CaFJ plugs, connectors, for the reactive metals. The story of Davy's containers, and windows for his apparatus. voltaic pile follows in the next chapter. Fluorine (Fa is the most reactive and corrosive of the oxidizers. Metals, carbon, and even water burn in fluorine with a bright flame. Fluorine is used in producing fluoro- chemicals and freons (chlorofluorocarbons, Fluorine CFCs), high-temperature plastics, and etched F 9 18.998403 glass products. Fluoride in drinking water and [L. fluere, flow] toothpaste helps prevent dental caries, but an Hydrofluoric acid known since 1700s, excess of fluoride is toxic. element isolated 1886 -219.6";hp -188. 1"; density 1.70 g/L Fluorspar (CaFJ has been known since Chlorine the 1500s. In 1670 the glass cutters of C1 17 35.453 Nuremberg discovered that fluorspar when [Gr. chloros, greenish yellow] treated with acids etched glass. Various Discovered 1774 investigators who studied this *acid of ma-lOl.OO; hp -34.6"; density 3.21 g/L fluorspar" (hydrofluoric acid, which is Scheele in 1774 reacted pyrolusite extremely poisonous) became ill and some (MnOJ with '' spiritus salis" (HCI) to produce

Figure 35. Henri Moissanprepares fluorinein his laboratoryat the kcole de pharrnacie in Paris.The search for the extremelypoisonous elemental fluorine killedseveral investigators. 38 a gas with a suffocatingodor, which he called Previously, brominewas used in the pro- "dephlogisticatedmuriatic acidn (CIJ. Lavoisier thought all acids contained oxygen, and it was natural to think of the gas . as a loose compound ofhydrochloric acid and oxygen. However, in 1807 Davy chose the simpler interpretation- a "simple" substance, and he named it chlorine. This explanation was gradually accepted;and after iodine was Figure36. 6.6'-Dibmmoindiga,the purple dye discovered and characterized by the early in "Tyrian Purple" or "Royal Purple," which 1800s, chlorine wasuniversally accepted as an was extractedfrom the straight-spinedMurex element. tmculus,a Mediterraneanmollusk. Tyre, a Phoenician city on the EasternMediterranean, Chlorine (ClJ is used world-wide to was well knownfor its purpledystuffs and render watersafe for drinking. It is used in the silken clolhiry. Theport of Tyrestank with the production of paper, textiles,petroleum protons of roltiw gastropods thathad been ducts, medicines, insecticides, solvents, paints, discardedafter the dye had been extracted. and plastics. Itis used as a bleach and disin- fectant. Chlorineis toxic and was used as a duction of ethylene dibromide, a lead (Pb) poison gas in World War I. scavenger used in making gasoline antiknock compounds. Bromine Br 35 79.904 Iodine [Gr. bromos, stench] I 53 126.9045 Discovered 1826 [Gr. iodes, violet] -7.2"; 58.8"; segz: 3.12 Discovered 18 11 Balard reacted Montpellier, France, 113.5"; 184.4"; 4.93 brines with chlorine and prepared a dark red Bernard Courtoisdiscovered iodine when liquid. After his presentation to theFrench he added an excess of sulfuric acidto a academy, his material was rapidly acceptedas concentratefrom marine algae; beautiful violet a "simple body" (element). Other chemists clouds effused and condensedon cold glass to had just missed the discovery - Liebig, for form darkcrystals with a strange metallic-like example, had a bottle of bromine thathe had luster. Davy showed in 1814 that these dark labeled "liquid iodine chloride." Chagrinned, crystals were anelement, because theycould Liebig placed thebottle in his "cupboard of not be decomposed by a red-hot carbon mistakes." filament. Bromine (BrG is the only liquid Iodine (Ij is found in the ocean whereit nonmetallic element. It is found in brine is assimilated by seaweeds. Iodine is mixtures. When not sealed, thick red-brown principally extracted from salt brines and fumesare given off that have a choking odor. Chilean saltpeter, where it existsin the form It is used in making fumigants,flameproofing of iodates. Lack of iodine is the cause of agents, and organicbromides for photography. goiter, and "iodized saltn contains a small amount of iodide for this purpose. Iodine is and blue. The tern "fluorescence" - emission used as an antiseptic in medicine.The black of a light stimulated by incident light solid sublimesat roomtemperature to produce (typically, brilliant colored light produced by a violet gas that is irritating to the eyes, nose, ultraviolet light or "black light 3 - originates andthroat. fromcertain EnglishJltzorspars (the old name for fluorite) which glowed when exposed to ------daylight. Sat ammoniac (NH,Cf) is formed near Brines, fonned by the evaporation of sea volcanicfumaroles; it was named for the salt water, are composed mostly of sodium chloride of Ammon, near the Oracle of Ammon in (halite, NaCl), although bands of potassium Egypt, where it wasprepared by the Arabians. chloride (sylvite, KC[) also occur. Halite is nistemple was made famous by Alexander the named for the Greek "hals, " salt. Sylvite is Great, who was crowned a Pharoah there. namedfor "Sal digestivus Sylvii, " or digestive Many ofthe coins of Alaander the Great show salt of Francis Sylvius de le Boe, a Dutch him with the horns of Amrnon Egyptian physician of Leyden. Sylvite is much less - religion frequently portrayed Ammon as a ram. common in nature than is halite, because most The "volatile alkali" which was produced by of the potassium is locked up in the earth's reacting sal ammoniac with lime was fo crust in clays and feldspars. become known as "ammonia. It is sometimes diflcult to distinguish " Sal ammuniac is also found as musses of halite a.nd sylite in thefie& because they can icy dagger-like crystals, fonned as a sublimate assume similar crystalline habits (cubes), fromburning coal seams. Burning coal mines Sylvite is a little more mringent to the tongue are also the home of other exotic minerals, (and tastes likz "low sodium salt" available at such as SeO, (downyite) and As,O, (arseno- food mankets), but this test is too subjective to lire). Downyite is so hygroscopic that it quickly be a reliable indicator. The two minerals, absorbs atmospheric moisture and dissolves to however, can be distinguished by testing with droplets of selenow acid. a sodium tetraphenylborate ((NaB(C,H,)J solu- The "sal mirabile" that Gtuuber discov- tion, A distilled water washing of the mineral, ered, NaJ0440H,0, is found in nature on of on& a few milliliters, is dropped into a test rare occasions. It crystallizes out of salt lakes solution. Halite produces no change; sylvite during winter due to decreasing solubility at causes the formation of a cloudy precipitute low temperatures. Its name is "mirabilite." from insoluble potassium tetraphenylborate. nere also mists a mineral bearing his name, Even though bromide and iodide exist it1 "glauberite," Na,Ca(SUJ, which forms as a marine water, they do not crystallize out as marine evaporite. alkali halides; instead in nature they appear Probably the most bizarreformula for a mainly as the silver halides bromargyrite - halide is KNa,(SO$,(CO,),Cl, for hanksite. (AgBr) and iodargyrite (AgI). Both minerals This mineral looks like mdti$aceted lemon were discovered in Mexico. drops and isfound at Searles Lake,Calvomia. Fluorides as minerals are almost The local populace collects them by dyna- exclusively in the form of fluorite (C~J, miting the mud Pats of the lake artd collecting which commonly form beautifir1 cubic and the strewn gems in buckets. octahedral crystals of green, yellow, purple, 6. HUMPHRY DAVY AND THE VOLTAIC PILE

he distinctionbetween soda and potash nitrogen, since it had been shown that was not made easily. Only gradually ammoniumcontained that element. It remained Twas it recognized that there was a for Sir HumphryDavy (Fig. 37), at the begin- difference between "plant alkali" (potash), ning of the nineteenthcentury, to decompose obtained from the ashes of plants, and soda and potash to the elemental substances. "mineral alkali" (soda), found in salt flats and Davy was well educated and became an evaporated seawater. In1683 Johnan Bohn assistantlecturer and director of the laboratory prepared "cubic saltpetre" (sodium nitrate) at the Royal Institutionat London. He became from a mixture of salt and nitric acid, which interested in electrochemistry and tried to he recognized as different from the ordinary saltpetre(potassium nitrate) by the shape of its crystals and its taste. Stahl himself distinguished between natural alkali (soda) and artificial alkali (potash) in 1702. Several other investigatorscontinued to characterizethe two alkalis, with the most definite account by Marggraf in 1759 who prepare very pure samples of "cubic saltpetre" and "prismatic saltpetre" from which he made gunpowder (from sulhr, charcoal, and saltpetre). The "cubic saltpetre gunpowder*flashed yellow and the "prismatic sdtpetre gunpowder" flashed blue. But the true nature of the two alkalis remained unknown. Figure 37. Sir HurnphryDavy, who first may isolated the reactivealkali metals and WithLavoisier's amazing insight, it alkalineearths byelectrolysis. seem strange thathe did not include sodium and potassium in his list of the elements. He electrolyticallydecompose the caustic alkalis explained that he did not include the "fixed with a voltaic pile (Fig. 38). First attempts alkalisn in his list of thirty-three substances accomplished nothing but decomposing the because he believed they were compounds, water of the aqueous solutions. Recognizing although the "nature of the principles which his mistake, he fused anhydrous potashitself, enter into their compositionis still unknown." and to his great delight observedflames at the We may pardon thiserror when we realize that cathode. Upon closer examination metallic the alkali metals did appearto be unique. He globules, appearing like quicksilver, were even suspected that they might contain being generated at this negative pole which quickly burst into flame. Able to collect a few ancients. The ancient Romansunderstood that of these globules, he observed that when timestone(calcium carbonate) whenheated in tossed into water they raced about swiftly and a kiln produced lime (calcium oxide),which burst into a beautiful lavender light. Davy served as excellent mortar. The explanation continued his investigation and found the was that "water had boiled out of the flames were caused by the ignition of limestone," notcorrect but consistentwith the hydrogen which was being generated upon observationthat weight waslost in the process. contact with moisture. He named this element Another compound of calcium, gypsum potassium after potash. According to wit- (calcium sulfate) when heated produced nesses, upon his discovery Davy danced about another form of mortar used in Egypt. This the laboratorywith ecstaticjoy. mortar, which had lost water, was later called Plaster of Paris. Later explanations of this slaking of lime includedthe interpretationthat limestone andbaryta were elements, although Lavoisier correctly believed they were oxides of elements not yet prepared. Methods then available whichwere employedto provide the metallic elementsby reduction of the oxides - principally heating with charcoal - were not Figure 38. Thevoltaic pile used to develop powerful enough,and the preparation of the the voltage toelectralyze salts to produce the metallic elementshad to await theelectrolysis elemental metals. Discsof zinc aridsilver techniqueof Davy. were separated by discs of moist cardboard In the 1750s, the work of Joseph Black, or leather. a professor of chemistry at Edinburgh, Scot- Davy immediately turned to soda, but land, was pivot.in elucidating the true nature found it couldbe generated only with "greater of the slaking (calcining) process(Fig. 39). intensity of action in the batteries," (i.e., Black investigated bothlime and ma~nesia greater voltage). He named this new element sodiumafter soda, only a few days after the discoveryof potassium. Many chemists believed that these "elemental metals" sodium and potassium were in fact compounds madeup of the dkalis + hydrogen. This hypothesis appeared to be reasonable, since ammoniumwas ammonia + hydrogen. However, it was promptly shown that no hydrogen could be evolved from the metal itself, and the elemental nature of sodium and potassium was universally accepted. Flushed with success, Davy turned to the alkdine earths. Compounds ofcalcium had Figure39. JosephBlack. who elucidatedthe figured prominentlyin the technology of the true name of "fixed air" (carbondioxide) alba, a medicine sold in Rome. He determined quicklime + mild alkali = limestone + that the loss of weight during the calcining caustic alkali,ix., process was due to a compound he called CaO + NqCO, = CaCO, + NqO "fixed air" (carbon dioxide). Thisair could be Black came close to suggesting the "fixed" (madesolid) by reacting again with atomic theory of gases by suggestingthat the the metal oxide. Working principally with fixed air was dispersed throughthe atmosphere calcium and magnesium compounds,Black in the form of an "extremely subtile powder." showed that: Black continued his studies to show that fermentationand combustionevolve fixed air limestone = quickline + fixed air, i-e., by mixing this air with lime water, producing CaCO, = CaO + CO, the milky product of precipitated lime (calcium carbonate). This test of identifyingcarbon magnesia alba = calcined magnesia+ dioxide existsto this day in the laboratory. fixed air, i.e., Yet another alkalineearth oxide - baryta MgCO, = MgO + CO, - had been produced Scheelein 1774. This earth, namedbecause of its heaviness, had limestone + acid = calcium salt + been first observed in "Bologna stone," fixed air, i.e., discovered in the 1600s by Vincenzo Casciar- CaCO, + 2H+ = Ca+' + W,O + CO, 010, a shoemaker and alchemist in Bologna. This stonephosphoresced when mixed witha magnesia alba + acid = magnesia salt combustible substanceand heated. + fixed air, i.e., Meanwhile, a mineral from Strontian, MgCO, + 2M+ = Mg+, + H,O + CO, Argyleshire, Scotland was analyzed by Craw- ford and Hope, both of whom concluded in the At that time it was believed that the late 1700s that anearth was present thatwas calciningof dl mild alkdis (carbonatesof the intermediatebetween calcium and barium. alkali metals) involved the combinationwith The stage was now set for Davy to "an acrid principlen fromthe fire to form the demonstratethat his method for potassiumand caustic alkalis (oxidesor hydroxides of the sodium could be used as a general procedure. alkalimetals). Black showed the true nature of One by one he decomposedsalts of calcium, this process by demonstratingthat: magnesium, strontium, and barium by a special recipe he developed (and suggestedby Berzelius, who had already experimentedwith voltaic cells): he electrolyzed a mixture of moist alkaline earth oxideand mercury oxide to produce the amalgamated metal. The free metal was then prepared by volatilizing the mercury by heating. Davy produced each of these metalsin 1808. The sample of magnesium that Davy prepared was very small - it was not until Figure 40. MicheIangelo'sstatue of Davidis 1831 that Bussy prepared magnesium in composedof marble, calciumcarbonate. substantial amountsnot by electrolyzing the salts, but by reacting the salts with metallic very light, alkali metalmust be constituting potassium. the difference. In 1855 R. Bunsen and A. Another elementthat caused Davy dif- Matthiesen isolated the metallic element by ficulty was lithium. Lithium had been known electrolyzing lithiumchloride. only for a short period of time - the presence Lithium is lightest of all the metals, with of this element was not suspected until the one-half the density of water. Lithiumreacts early 1800s when Arfwedson (in Berzelius' with water, but not as vigorously as sodium. laboratory) analyzed petalite(LiAISi,O,J and Like the other alkali metals, lithium can be cut found a difference between the observedand easily with a knife, and the freshly exposed calculated total weight. Too small to be surface rapidlytarnishes in the air. Lithiumis accounted for by sodium, the discrepencywas used in light-weight structural alloys and in explained by the presence of a new, lighter batteries. With the highest specific heatof any alkali (in 1818). Several investigators, solid element, this element is used in heat includingDavy, promptlytried to decompose transfer applications. Lithium carbonate is the alkali salt by electrolysis,but only minute used in the treatment of manic-depressive and impure samplescould be obtained. Only in psychoses. 1855 could sufficientquantities of pure lithium be prepared, from purelithium chloride by Bunsen and Matthiessen in Germany using a Sodium powerful battery bank. Na 11 22.98977 These metals of Davy were used to [Eng. soda, L. natrium] isolate a whole new series of elements which Sodiumcompounds known to ancients, could not be obtained by direct electrolysis- element isolated 1807 but the story of this new group of elements 97.8"; hp882.9"; sllgr 0.97 will wait until the next chapter. Until the 1700s, chemists did not differentiate "mineral" or "natural" alkali (Na$Oa found in shallow mines and "vegetable" or "artificial" alkali (K,CO,) collected by Lithium leeching water throughwood ashes. In 1702 Li 3 6.941 Stahl distinguished betweenthe "natural and artificial alkalies" by the difference in cry- [Gr. lithos, stone] stallineforms of their salts. In 1759 Marggraf Discovered 1817, elementisolated 1855 distinguished the twoalkalis in a dazzling 180.5"; 3402"; 0.53 experiment cubic saltpeter (NaNO,) gave a At the end of the eighteenth centuryde - yellow flash in gunpowder and prismatic Andradacollected twominerals in Scandinavia saltpeter (KNO,) gave a blue flash. In 1807, which he named petalite and spodumene. Sir Humphrey Davy prepared the metals Although several chemists analyzed these through electrolysisof the molten caustic soda minerals, including Vauquelin (who had and potash (the hydroxides) and named the recognized beryllia), none correctly inter- elementssodium and potassium. preted the puzzling "loss of weight." Johan Sodium metal reacts rapidly with water, Arfwedson repeated meticulous analyseson the frequently igniting theevolving hydrogento minerals in 1817 and concluded that a new, form a yellow flame. Sodiumforms soluble In a few decadesEpsom becamea fashionable salts with virtually all the anions, organicas spa for Europe. Thus was created"Epsom well as inorganic, and is importantto animal saltsn (MgSO,) which eventually becamea nutrition. The most common compound is world-wide health remedy.Magnesia had been sodium chloride(table salt). knownsince ancient times- it is mentionedin a treatise by Hippocrates.During the early eighteenthcentury, a panacea calledmagrtesia Potassium alba (magnesium oxide) wassold in Rome, K 19 39.0983 and was identifiedas the earth obtainedfrom [Eng. potash, pot ashes; L. kalium] Epsom salts.In 1755 Dr. Joseph Blackshowed Potassiumcompounds to ancients, that magnesiais entirely differentfrom lime elementisolated 1807 (CaO). Davy prepareda sampleof the metalk 63.2"; 12g 760"; 0.86 elementby meansof his voltaic pile in 1808. In his list of elementsLavoisier listed For his researchBlack is consideredby some thirty-three substances,but did not include to be the proper "discoverernof magnesium. potash and soda - he considered theseas Magnesiumis a fairly toughmetal and "evidentlycompound. " Sir HumphreyDavy's can be used as a structural material;one-third electroIysisexperiments demonstrated that the as light as aluminum, itis essential for principles of potash and soda were indeed airplane and missile construction. However,it elements. The methods developed by Davy can burn with a blindingwhite flame,and is allowed the production ofpotassium and used in flashlight photographyand pyro- sodium for hrtherchemical procedureswhich technics. The hydroxideMg(OH), is used in requiredstrong reductive conditions,resulting medicine (milk of magnesia). Magnesiumis in the discoveryof even moreelements. criticalto photosynthesis, because chlorophyll Potassium and sodium are essential to is a porphyrin(a heme-likemolecule) with a nerve transmission;potassium is the universal centeredmagnesium atom. cation foundin bothplants and animals,as the principal saltin extracellularfluids, andis used in fertilizers. This element ignites Calcium spontaneously inwater with a violet flame. Ca 20 40.078 [L. calx, lime] Limeknown to ancients, Magnesium elementisolated 1808 Mg 12 24.305 839"; hp 1484"; 1.55 [Magnesia,district in Thessaly, Greece] Limestone (calciumcarbonate, CaCO,) Magnesia knowto ancients, and gypsum (hydrated calcium sulfate, elementisolated 1808 CaS0,m2H20), the principal minerals of 648.8";& 1090"; 1.74 calcium,have been known and utilizedsince In the early 1600scertain wells in ancienttimes for plastersand cements. When Epsom, England, deliveredwater so bitter that gypsum is heated, the dehydratedpowder the cows would not drink it - but it was (Plasterof Paris, CaS0,m%H20)can be mixed discoveredthat the watercould heal wounds. with water toproduce plaster, which setsto generate the originalhydrated sulfate. When tium-90, with a half-lifeof 28 years, is a limestoneis heated, carbon dioxide is liberated component of nuclear fallout and can poten- to give calcium oxide. Additionof water gives tial!~be a health problem by incorporationin slaked lime, calcium hydroxide,which can be bones. Uses of strontium are similarto those molded until hardeningtakes place by reaction of barium and calcium, but are limited because with atmospheric carbon dioxide to produce of the much greater cost. the original calciumcarbonate. This slaked lime was used to cement together sand and stone into a primitive concrete. The Romans Barium discovered that burning a mixture of limestone Ba 56 137.33 and silica dramaticallyimproved the material. [Gr. bays, heavy] In 1824 the patent issued for Portland cement Baryta discovered 1774, was only a refinementof this ancient techno- element isolated 1808 Iogy. Davy in 1808 prepared the elemental 725'; hg 1640"; gr 3.5 calcium with his voltaic pile. In the early 1600sVincenzo Casciarolo, Calcium exists abundantly in bones, a shoemaker and alchemist in Bologna, teeth,shells, coral, andlimestone. In the form reported that when heavy spar (barite) is of carbonate, this element causes hardness in mixedwith a combustible substanceand heated water and produces cave formations. red-hot, the resuIting "Bologna stone" became phosphorescent.Marggraf found the stoneto be a sulphate, but believed it had lime (CaO) Strontium as a base. ScheeIeand Gahnin 1774 concluded Sr 38 87.62 that the earth instead was a new principle, [Strontian, town in Scotland, sourceof called baryta or "earth of heavy spar." Davy original strontianite] prepared the metallicelement in 1808 with his Recognized as element 1790, voltaic pile. element isolated 1808 Water-soluble barium salts are poi- rn~769"; hp 1384"; 2.54 sonous, but barium sulfate is insoluble and is Dr. Adair Crawford analyzed a mineral used as a "barium cocktail" allowingX-ray specimen collected at Strontian, Scotland, images of the otherwise invisible digestive which supposedly was a mixture of "cal- tract. Barium sulfate is also used as a white careous and ponderous spars" (CaCO, and pigment in paint (blanc jZre). The metal is BaCO,). He recognized the existence of an used as a "getter" in vacuum tubes. earth with chemicalproperties quite different from calcium or barium. The next year it was shown that the spectrumalso was different - Limestone beds were laid down by strontia produced a "candle red" color, while invertebratesmadalgae in the ocean millionsof calcium produced red, and barium green. In years ago. The mineral in limestone is calcite, 1808 Davy isolated the element in the manner a rhombohedralform of calcium carbonate, as for calcium and barium. CaCO,. Iceldspar, a form ofcalcite, exhibits Thesalts of strontiumproduce a brilliant double refraction.Calcite is the most common crimson flame used in pyrotechnics. Stron- carbonate innature. 7. USING DAVY'S METALS

avy's discovery of preparing elements electrolytically opened up a whole Drealm of possibilities - metals which had been hidden up in combined form in the earth's crust now could be isolated and their unusual chemical and physical properties could be explored. Flush with success and optimistic about unlocking the mysteries of the remaining elements of the Periodic Table, Davy attempted to purify many additional metals. However, there were unexpected difficdties - for example, aluminum and silicon were too tightly bound in their polymeric oxides, the feldspars and clays of the earth. Additional Figure 41. Bernard Palissy, "a workerin techniques needed to be developed, many of clay," who developedthe art of glazing which utilized Davy's very reactive metals. pottery and faience in Frame. He was Boron. Borax (N~B4O,(OH),.8H2O) familiar with "zaffer,"or cobalt blue. usedin was known by the ancient name of "tincal. " glass. A great deal of his researchwas devotedto the crystallizationof salts. Obtained originally from the Far East, it was found to be a very efficient flux in the instances were cleaner and preferable to blowpipe analysis of minerals. Boric acid itself Davy's voltaic pile, and this technique was (H,BO,), first prepared in 1702 by Willem adapted to manyadditional elements. Hornberg, was rapidly recognized as a Sicon. The two most common elements "sedative saltn for various ailments. By the in the earth's crust - silicon and oxygen - middle 1700s borax was recognized as a constitute quartz, silicon dioxide. The use of compound of "sedative salt" and "soda," and quartz in the manufacture of glass was a despite the similarity of compounds of alum- sophisticated art even with the ancient inum and boron, the two were acknowledged Egyptians. However, the exact nature of as separate. Lavoisier recognized boron as an quartz was not well understood for centuries - element. PaIissy (Fig. 41) thought that "rock crystal" Davy was not able to prepare the metal had been precipitated from water "like by electrolysis, but he was able to prepare the saltpetre," but since the crystal could not be element by reacting boric acid with potassium redissolved, the prevalent explanation was that in 1808. Simultaneously, across the English it was water that had been "frozen very hard" Channel, Gay-Lussac and Thenard isolated (Fig. 42). A century later Boyle showed this boron using the same method. By now it was could not be, since quartz was much heavier being recognized that the reaction of a than ice. (Today we know that quartz is indeed compound with hot potassium in some precipitated from geothermal aqueous solu- Aluminum. Alum (potassium aluminum sulfate) had been used for centuries as a mordant in the dye industry.Early scientists believed that alum containedlime, but Lavoi- sier recognized that a separate element was present. As with silicon, aluminum could not be separated electrolytically, but 0rsted in 1825, and WiiMer in 1827 were able to isolate it by reacting metallicpotassium with aluminum chloride. W6hler (Fig. 43) found that Figure42. Quartzcrystal, SiO,, composed when he conductedthe reaction in platinum of the two most commonelements in the crucibles the aluminum reacted with the earth's crust. platinum, and so he resorted to porcelain tions). Lavoisier's brilliant mind understood crucibles. that quartz must contain a basic element which Deville was able to prepare very pure was named after "silex," Latin for "flint. aluminum by developing a procedure of When Davy was not able to isolate passing aluminumchloride vapor over molten silicon by his atomic pile, he attempted to sodium. It was later found that the reaction prepare the elementby passing potassium proceedsmore cleanly and easily with sodium vapor over hot silica (silicon dioxide), and aluminum chloride, which acts as a flux for even this failed. Berzelius heated potassium the process. Devillewas under the employ of fluosilicate (&SiF,) with potassium and Napoleon 111, and was able to prepare obtained a brown mass in 1824 which he silverware for the emperor, who prized his purified by washing with excesswater. Pure, collectionand saved it for use at banquets by crystalline silicon was prepared by Devilleof the most important of guests (silver was for Paris in 1854 along with his experimentson the"second-rate" visitors). Hence, aluminum aluminum. was called the "silver fromclay." In 1884 the Washington Monument was capped with a solid aluminum tip, since the metal was so "valuable and precious." The breakthrough to the production of this element, which is so abundant in the earth's crust, was found by Charles Hall (Fig. 44), an Americanchemist who discoveredthis process when only a student at Oberlin College. In 1886 he burst into his professor's office with his handful of precious buttons of aluminum. The Aluminum Company of America nowcherishes this collectionand has Figure 43. FriedrichWfihler, who isolated dubbed them as the "crown jewels." Since aluminum,yttrium, and beryllium. He also others did not comprehendthe importance of demonstratedthat organic compounds Hall's discovery, he was able to patent his contain no vital force by interconverting inorganic and organic cornpouds. process independently.His method was based the officialname. Wohler (Fig. 43) prepared metallic berylliumin 1828 in the samemanner as for aluminum (by reactionof berylliumchloride with potassium). Beryllium is now know to be very poisonous,and extreme precautions mustbe takenduring millingor sawingof the metal or its compoundsto avoid exposureto its dust. Salts as well are poisonous- which thankfully . . did notlead to the demiseof the early chemists [Z..4 . .-Y ~':2 who customarilytasted chemicals. Zirconium. Zirconiumis the basis of an ancientgemstone, just asis beryllium.Zircon Figure 44. Charles HaIl. who developedthe (ZrSiO+J(Fig. 45) has been called historically commercialprocedure for producing aluminum fromcryolite (Na,AIFd). upon the work of Deville, and involved the electrolysis of cryolite (Na,AIF,). This electrolysis proceedssimilarly to thatof silicon, wherethe complexfluosalt functioned quartz b~l as a flux for theprocess. Cryolite- which was named because it meltedeasily, "like frozen brine" - had been discoveredin Greenland in1872. A codiscovererof the cryoIiteelectro- lytic processwas Heroult,who unfortunately zircon corundum announced his discoveryat about the same time HaIl filed his patents, and Hall generally is credited with this industrially monumental process. Beryllium. In Roman timesberyl (Fig. 45) and emeraldwere suspected to be closely related. Hauyof the &ole des mines inParis tourmaline colemanite (Fig. 46) recognizedthat the two had identical crystallinestructures, and he asked Vauquelin Figure 45. Crystal structures of minerals containingSi, Be, B, Al, and Zr: quartz 47) analyze the two mineralschemi- (Fig. to (rock crystal, SiOJ; beryl (or emerald, cally. Vauquelin in1798 found eachcontained BqAI,Si,O,J;zircon (ZrSiO,); corundum silica, alumina,and a new substancehe named (or ruby,A1203; tourmaline (a complex "glucina" on the basisof the sweet tasteof its boroalumimsilicate);and colemanite saIts (emerald/berylis a beryllium aluminum (~B,011~5W,0).All can be gemstones exceptthe last, whichis too soft; it is a silicate).Since yttria forms sweet salts as well, sourceof boronin the Death Valley Region to avoid ambiguity"beryllia" was acceptedas of California. by various names, including jacinth and silicon in 1824 by heating potassium hyacinth. Becauseof chemical similaritiesof fluositicatewith excess potassium. zirconium and aluminum, early chemical As the second most common element, examinationssuggested "silicaand alumina" silicon is found in a remarkable variety of were the basic componentsof zircon. Klaproth minerals and can be used to produce a very first recognized the new earth in 1789. Davy great number of useful materials, including attempted to isolate this metal, but was refined element for transistors, silicates in unsuccessful. Berzelius isolated the metal in glasses and ceramics, and silicones in ther- 1824 by reacting potassium and potassium mally resistant polymers. Ordinary beach sand zirconium fluoride. is quartz, siticon dioxide. Diatoms in water use siIica from the water to buiId up their cell walls. Aluminum A1 13 26.98154 [L.alumen, alum] Alum knownto ancients, element isolated 1825 660.4"; hp2467"; 2.70 The ancient Greeks and Romans used - ?_I Figure 46. Red-JustHaily, who discovered alum (various aluminumsulfates) in medicine the laws of crystallogmphy.He urderstood and as a mordant(fixer) in dyeing ~10th.In the thata crystalcan becleaved into smaller Middle Ages and Renaissancean active alum crystals with identicalgeometries. He proved industry was thriving. Marggraf in 1754 was fbat emerald and beryl were identical suucturally. the first to recognize that the earth in Jum

Silicon Si 14 28.0855 [L. silex, flint] Quartz known to ancients, dement isolated 1824 1410";hp 2355"; sr, 2.33 Since prehistoric times, rock crystal (silica, SOz) has been usedin the manufacture of jewelry, vases, and glassware. Sir Humphry Davy, who broke downso many compounds to produce elements with his voltaic pile, Figure 47. Louis-NicolasVauquelin, who couId not decompose silicaand believed it was discovered chromiumand beryltiurn.He also not an element. Berzeliusprepared elemental discovered asparagine, the amino acid, in =Paraw. must be different from that in limestone, and page 50). Me isolated the same earth (oxide) he demonstrated thepresence of this alumina from both minerals, thus establishinga new in clay. Davy, who had been so successfulin element existedas the basis for each. The new separatingother metals by means of his voltaic elementwas first prepared in 1828 by WohIer pile, could not isolate the element. Orsted in and Bussy by the action of potassium on 1825 and Wlihler in 1827 reacted aluminum beryllium chloride. Vauquelin had suggested chloride (preparedby passing chlorine overa that the new element be named glucina mixture of alumina and charcoal) with because its compoundsare sweet. This habit of potassium to make powderedaluminum. By testing beryllium compounds by taste was 1845 Wiihler was able to melt the powder to a discontinued when it was learned that these metallic ingot. Commercial production of compounds were poisonous.Since yttrium aluminumwas made feasibleby the discovery salts also are sweet, Klaproth suggested the of Hall in 1886 that alumina dissolvedin name beryllium instead of glucinum. cryolite (Na,AIF,) could be electrolyzed to Berylliumhas one of the highest melting produce pure aluminumin quantity. points of the light metals(1278"). Beryllium Aluminum is the most abundantmetal on resists attackby nitric acid and can be used as earth, but was discoveredonly recentIy owing a structural material.It is used as an alloying to the difficultyin extraction fromaluminum agent to produce berylliumcopper which has ores. Today metallic aluminum is inexpen- exceHent spring characteristics.The oxide, sively produced by electrolysisof an artificial beryllia, has a surprisingly high thennal mixture of sodium,aluminum, and calcium conductivityfor an insulator. Beryllium and its fluorides. Aluminum is used in scores of saltsare very toxic and care must be taken not industrial and domestic applications where a to inhale beryllium or beryllia dust. cheap, light-weight, easilyfashioned structural material is needed. The oxide layer that forms on aluminum forms a protective coating,and Boron aluminum is ideal as a reflective materialon B 5 10.81 telescope mirrors. [Ar. Buraq, borax] Borax knownfor centuries, element isolated 1808 Beryllium 2079"; hp(sublimes) 2550" ; sp 2.34 Be 4 9.01218 Samples of borax (%&!40,), called [Gr.beryilos, beryl] tincal,arrived fromthe East Indies during the Beryl known to ancients, beryllia recognized Renaissance. It was used in the purification in 1798, elementisolated 1828 and fusion of metals. Boric acid (H3B03)was mg 1278"; lg 2970"; 1.85 prepared in 1702 by Wilhelm Homberg and Until 1798, it was not realized that was originally called"sedative salt" before it emerdd and beryl were the same mineral. was recognized as a weak acid. In 1808 the Haiiy, who founded the atomic basis for compositionof boric acid was ascertained by crystallography, had seen identical cry st$ Sir Humphrey Davy in England and by Gay- patterns for each, and at his suggestion Lussac and Thenard in France, when it was Vauquelin analyzed the two (Figs.46 and 47, reduced by metallic potassium. The French and the British chemists originally called the ceramics industries. Lunarrocks have shown new element bore and boracium, respectively. a surprisingly high content of zirconia. Boron is found in nature in the form of borates. Boric acid is so weak that it can be . used to wash out the eyes. Borax is used as a Carefir1 analytical work in the laboratory cleansing flux in welding and as a water was becoming increasingly important in the softener in detergents. Boron is an extremely advancement of chemistry. In the 1700's there hard crystal, nearly as hard as diamond but too had beet1 much sloppy analysis which could be brittle to be useful. Boron filamentsare high- characterized as "semiquantitative" at best. strength, light-weight fibers used in aerospace Whenever there had been a dispariry between composite materials. observed and predicted values (when the total weight did not add up to 100%), it would be easy for an "unaccountable loss" to be dis- Zirconium missed as "qerirnental error. " Undoubtedly Zr 40 91.224 manydiscoven'es had been missed this way. [Zircon,gemstone] Around 1800 Vauquelin of Paris and Zircon known to ancients, oxide discovered Klaproth of Berlin were recognized as the best 1789, metal isolated 1824 analytical chemists of the day, and these 1852"; hp4377"; 6.51 skilled scientists were oJen consulted by others Jargon and hyacinth (zircon, ZrSiO,) not so skilled in this art. The meticulous care have been prized as precious stones for of these two chemists led to Vauquelin's centuries. The presence of an unknown observation of the small discrepancy in the element was not suspected, owing to the simil- analysis of beryl that led to his discovery of arity of zirconia to alumina. It took the craft of beryllium, and likewise to Klaproth's carefir1 Klaproth to recognize the new earth, who in work that allowed him to recognize that the 1789 analyzed the mineral correctly for the earth in zircon was direre~fromaluminum. It first time, reporting 25% silica and 70% is to the credit of these professional scientists "jargonia" (zirconia). Davy attempted to that mutinely they gave the credit of "original decompose zirconia, but was unsuccess!U. discovery" to others whohad peflormed the Berzelius in 1824 obtained the metal by initial, and even inconclusive, work. reacting zirconiumfluoride with potassium. A few decades later Benelius of Sweden Zirconium is mostly used in commercial lifred analytical chemistry to new heights. In nuclear power plants - with a low absorption his loboratory he carried out the painstaking cross section for neutrons and with a high analysis @hundredsof substances to dejine an resistance to deterioration, it can be used to accurate listing of atomic weights, necessary clad radioactive fuel elements. Zirconiumis to develop a Periodic Table in the mid-1800s. also used where corrosive-resistantmaterials Adhering to the demanding standards of are needed, such as surgical instruments, Berzelius' laboratory, his assistant Awedson photoflash bulbs, and explosive primers. discovered the lightest metal lithium by Zirconia (ZrO3can withstand heat shock and refiLsing to ignore afav percent discrepancy in can be used to Iine metallurgical furnacesand total weight of the Swedish minerals, petalite as a refractory material in the glass and and spodwnene, that he analyzed. 8. PLATINUM AND THE NOBLE METALS

latinum exists in native (elemental) form of a new metal during his voyages to South in nature,just as gold, and yet platinum America during 1735-36. While making Pwas not discovered until about five astronomical measurements and tours of trop- hundred years ago. Modern scientists have ical plantations, he observed nuggets of this often speculated why platinum had not been white metal which interfered with the gold discovered until comparatively recent times - mining near Choc6, Colombia. The new metal they thought perhaps references to platinum was hard and could not be as easily worked as could be ascribed to ancient dloy s. Hence, the gold, it could not be separated easily, and it Greeks' "electrum" or the alchemists' "aug- could not even be melted by conventional mentation of gold" might refer to the addition means,as could gold and silver. This account of of small amountsof platinum. However, no de Ulloa was published in 1748. definite older reference is certain, except per- Two years later Watson and Brownrigg haps for a randomdiscovery of platinum alloys contributed to Philosophical Transactioma in ancient civilizations (e.g., trim from caskets detailed description of this metal and marveled of Pharaohs). that this "platina" (Spanish for "silver") shouId Don Antonio de Ulloa, a Spanish scien- have been unknown for so long. "Gold is usually tist and explorer (Fig. 48), gave a description esteemed as the most ponderous of bodies, . ." and yet this new metalline substance was "specifically heavier." Since platinum could be used to alloy gold (thus "debasing" it), the Spanish government ordered all platinum "to be thrown into the river"! However, sizeable quantities of platinum accumulated in the laboratories of Europe as the scientists became strongly interested in this rehctory metal. Finally a method was found by Achard for fitsing it - implements of platinum, such as crucibfes, could be produced by molding a platinum-arsenic alloy and then heating to expel the arsenic. Priestley suggested that platinum might be fised with "dephlogisticated air" (oxygen) instead of ordinary air, and by 1801 Robert Hare (University of Pennsylvania) Figure48. Don Antoniode Ulloa, who gave had melted platinum with his newly invented the first definitiveaccount of platinumduring oxy-hydrogen blowpipe. Later Hare's student a voyage to South America during theperiod 1735-1736. Joachim Bishop founded the American platinum refining industry, but the prolific research on observed in the gold placers on the Siberian platinum did not commence, because of the Urals, south of Ekaterinburg (where chromium difficulty of working with it, until Wollaston had been discovered some twenty years before). conducted his famous experiments. Although Wollaston did not disclose his secret procedure for processing platinum until 1826, Russian metaIlurgists at St. Petersburg had devised a similar process two years before, and prodigious quantities of platinum were soon available from Russia. For about twenty years Russia minted several coins of various ruble denominations. Other metals from platinum - palladium and rhodium. Wollaston in his famed experiments found additional elements in the platinum family. These elements were less common components in the platinum he had been investigating. The first additional noble metal that Fiye 49. William WolIaston,discoverer of Wollaston isolated was palladium (in 1803). palladium and rhodium.Wollrtston developed This he isolated from a concentrated solution of a process for producing malleableplatinum. aqua regia solution of platinum, by adding thus allowingthe facile consawtionof mercuric cyanide to form a yellow precipitate platinumutensils. (palladious cyanide). The metal was easily William H. Wollaston (Fig. 49) was a produced from this precipitate by heating with British physician who retired to devote his fill sulfur and borax. WoIIaston named this element time to chemical research. Re found a method in honor of the recently discovered asteroid of producing malleable platinum that could be PaIlas. Rapidly it was discovered that gold, as filshioned into implements - in fact, it was this well, fiom South America contained palladium discovery that allowed Wollaston to retire fiom - indeed, "brittle gold" had at first been his medical profession at 34 years of age, in rebed by the Mint of England until it was 1800. His method involved dissolving platinum ascertained that the culprit was palIadium, which in aqua regia with a specific composition, then could be extracted out by simple procedures. reprecipitating the platinum by the carehl Gold-palladium alloys were recommended for addition and removal of ammonia. The result scientific and astronornicd instruments, and for was a fine "sponge" powder that could be metal used by dentists. compressed and heated in a mold. This method The second metal of the platinum family of fashioning objects from powdered metal that Wollaston discovered was rhodium. By anticipated the modem methods of sintered now he had perfected his procedure by metals, by which articles of high-melting metals dissolving platinum in aqua regia; then by could be manufactured fiom powders. adding ammonia precipitating the platinum in Well into the ISOOs, platinum was the form of ammonium chloroplatinate; then by considered an exclusive product of South precipitating the palladium by adding mercuric America. However, in 18 19 white nuggets were cyanide; then by collecting the filtrate and evaporating to dryness to produce a beautifid investigated. With 18 pounds of platinum red powder (sodium rhodium chloride). The residues fiom the Treasury of Russia, after element was produced easily by reduction with extensive chemical treatment he was able to hydrogen gas and washing out the sodium isolated six grains of the new metal from the chloride. portion of metal not soluble in aqua regia. Undissolved metals in aqua regia - Klaus then investigated the osmiridium fiom iridium and osmium. Smithson Tennant American ores and found about 1% ruthenium. discovered two additional noble metals which Form of noble metals in platinum. At did not dissolve in aqua regia. When platinum the time of their discovery, the noble metals had been dissolved in aqzra regia, a black palladium, iridium, osmium, and ruthenium were residue remained which had been assumed to be assumed to be in the form of platinum alloys graphite. However, Tennant in 1803 hrther dispersed evenly through the platinum. It is now investigated this powder and was able to knownthat these noble elements occur in the separate two new metals: one that imparted a form of microscopic inclusions with specific red color to amrnoniacal platinum solution compound formulas. Examples of such com- (iridium) and another whose oxide was volatile pounds include: and which had a vile odor (osmium). The black Osrniridium (Ir,Os) residue was thus named osmiridium. (Fourcroy Ruthenosmiridium(Ir,Os,Ru) and Vauquelin may be considered independent Iridosmine (Os,Ir) discoverers of iridium: see page 57). Platiniridium (Ir,Pt) Tennant andWoliaston were quite friendly Occasionally these inclusion compounds have with one another throughout their respective been dislodged fiom the mother lode and are careers, and even vacationed together in found as silvery flecks in stream beds and can be Northern Wand. Indeed, their close association panned like gold. Famous sites noted for these began at an early age - Wollaston had been rich streams include Alaska and Tasmania. Ternant's assistant who conducted a diamond- The platinum metals can also be found as combustion experiment which proved that sulfides, seletides, tellurides, arsenides, stan- diamond was carbon. nides, antimonides, and plumbides. Mineral- Ruthenium. Various scientists had ogists typically sell specimens of these alloys in subsequently investigated platinum ores and platinum cross sections with the inclusions could find nothing definite in addition to located by scanning electron microscopy (SEM) platinum, palladium, rhodium, osmium, and and the formulas identified by energy dispersive iridium. Sniadecki had studied 400 grams of X-ray (EDX). These inclusions can vary in size crude platinum ores in 1807 and believed he had Erom a micrometer upwards, Examples include: isoIated a new metal he named vestium (in Atokite ((Pd,Pt),Sn) honor of the asteroid Vesta). Although it Bowieite ((R.h,Ir,Pt),S,) appeared that he in fact had isolated a new Erlichmanite (OsSJ element, a commission in Paris could not repeat Iridarsenite ((Ir,Ru)AsJ the isolation with their sample of platinum ore. Palladoarsenide (Pd,As) Later in 1828, Osann isolated an impure sample Palladseite (Pd,,Se,,) which probably contained ruthenium. It Plumbopalladinite(Pd,Pb& remained for Karl Klaus to make a carefbl study Rhodplumsite (Pb,Rh,S& of Osann's work, which he repeated and firther Sperrylite(PtAsJ Compositions of "platinum nuggets" can vary widely and are probably the cause of Palladium inconsistent and irreproducible observations, Pd 46 106.42 notably during the search for ruthenium. [Gr.Pallus, goddess of wisdom] Discovered 1803 1554"; hg 2970"; s~~gr:12.02 Brazilian miners in the early 1700s Platinum recognized a natural alloy they called ortro Pt 78 195.08 branco (white gold), which was probably a gold-palladium alloy. One hundred years later, [Sp. pbtina, silver] Used by pre-Columbia Indians, in 1803, W. H. Wollaston separated palladium "discovered" 1735 from platinum by dissolving the crude platinum in aqua regia and precipitating the palladium as 1772"; hp3827"; 21.45 The pre-Columbian Indians of Ecuador the yellow palladious cyanide. By heating the had discovered platinum and manufactured yellow precipitate with sulfirr and borax he artficts of platinum-gold alloy. Don Antonio de obtained a button of the new metal which he UlIoa on a voyage to the New World fiom named palladim fiom the recently discovered Spain in 1735 rendered a clear description of the asteroid Pallas. Five years later he reported the metal from Choc6, Columbia; and Charles presence of grains of native palladium and Wood in 1741 returned a sample to the New platinum in Brazilian gold ore. World fiom Columbia. During the second half Palladium can absorb 900 times its own of the eighteenth century there was a great deal volume of hydrogen; hydrogen diffises through of research in the New World on platinum; its heated palladium and is used to puri@the gas. chemical inertness rendered it ideal for crucibles Powdered palladium is anexcellent catalyst for and and other utensils. In 1819 a white metal was hydrogenation dehydrogenation reactions of discovered in the gold placers on the Siberian organic compounds. White gold is alloy of gold slopes of the Urals. Three years later it was with palladium added. Palladium can be beaten identified as platinum. The first commercially into a leaf 0.1 prn thick. Palladium is used in dentistry, watchmaking, and surgical instru- profitable deposit of platinum in the Urals was ments. discovered in 1824, which began Russia's ~latinumindustrv. .r Platinum has a expansion coefficient the same as glass, and is used to make sealed Rhodium electrodes in glass assemblies. Platinum does not Rh 45 102.9055 oxidize in air at any temperature, and is used in [Gr.rhodon, rose] jewelry, wire, laboratory ware, electrical Discovered 1804 contacts, and in dentistry. Since it can perform 1966"; 3727"; 12.41 at high temperatures, it is used for coating W. H. WolSaston discovered rhodium in missile cones and jet engine nozzles. Powdered 1804 fiom a sample of crude platinum ore platinum is an excellent catalyst for producing originating fiom South America (the Russian sulfuric acid, cracking petroleum products, fbel platinum ores had not yet been discovered). He cells, and anti-pollution devices for automobiles. dissolved the crude platinum in aqua regia, and precipitated the platinum as the ammonium chloroplatinate by adding ammonium chloride, osmium, it is used for pen tips and compass and then precipitated the palladium by adding bearings. Iridium is used as a tracer for the cyanide. The filtrate yielded a dark red powder geologic. K-T boundary (fiorn a meteorite that -the complex chloride salt of sodium and of a - caused the extinction of the dinosaurs). Iridium new metal he called rbodirrm. The salt (sodium and osmium have the highest specific gravities hexachlororhodate hydrate, Na,RhCle 18H,O) of all the elements. was easily reduced with hydrogen to give the metal. Rhodium is mostly utilized as an alloying Osmium agent to harden platinum and palladium - used in thermocouple elements, electrodes for aircraft [Gr. osme, odor] spark plugs, and Iaboratory crucibles. Rhodium Discovered 1803 has a low electrical resistance, a low contact 3045"; hp 5027"; 22.57 resistance, and high resistance to corrosion, and The other metal Tennant isolated in 1803 is used in electrical contacts. Plated rhodium is was named osmium, because of its odor. very hard and is used for optical instruments. Osmium is dficult to fibricate in coherent form and is usually found in the powdered state. The metal is used to produce very hard alloys Iridium with other metals of the platinum group to Ir 77 192.22 produce fountain pen tips, instrument pivots, [L. iris, rainbow] phonograph needles, and electrical contacts. The Discovered 1803 tetroxide (OsO,) is volatile, has a strong odor, 2410"; 4130"; spgc22.42 is toxic, and is very damaging to the eyes. Smithson Tennant in 1803 discovered that Osmium is the heaviest element, only very when crude platinum is dissolved in aqua regia, slightly more dense than iridium. a black powder with a metallic luster remained. By alternate action of acid and alkaIi, he was able to separate this powder into two fractions. Ruthenium One metal he named iridium, because of the Ru 44 101.07 variable colors of its salts. Some chemists give [L.Rulhenia, Russia] independent credit for the discovery of iridium Discovered 2828, metal isolated 1844 to Fourcroy and Vauquelin, who the previous 2310"; hp3900"; 12.41 year found the same residue but did not separate Ever since platinum was introduced into it into two fractions. Descotils also had noticed the New WorId in the 1700s, it was zealously a red precipitate while studyingplatinum salts investigated in an attempt to discover new (due to an iridium complex) but had not isolated elements; in the early 1800s four elements - or characterized the new element. iridium, osmium, pdladium, and rhodium - Iridium is hard and brittle, difficult to were separated fkom platinum. In 1807 machine or work, but is the most corrosion- Sniadecki reported a new metal which could not resistant metal known - it is not attacked even be confirmed but which was probably by aqua regia. Iridium is used for making high ruthenium. Twenty years later platinum was temperature crucibles and electrical contacts. It discovered in Russia, and in 1828 Berzelius and is used as a hardening agent for platinum. With Osann investigated platinum ore from the Ural Mountains. Berzelius found evidence only of the in Manchester, conducted his studies on four elements recently discovered, while Osann meteorology and marsh gas. Priestley carried prematurely reported the presence of three new otrt his research in his personal home metals, which he named pluranium, polinium, laboratories in Lee&, Birmingham, and later in and ruthenium. Karl Klaus in 1844 showed that Northumberland, Pennsylvania. He discovered Osam's compounds were mostly crude oxide oxygen in the private luborutory of Lord mixtures of silicon, titanium, iron, and zirconia SheZbrme in BmODd, England Cavendish was - but did contain a new metal. From eighteen able toperj4onn his sophisticated experiments in pounds of crude platinum residues he received his maitsion laboratories that he finamedcfiom from the Secretary of the Treasury in St. hisfamily inheritance. Berzelius completed his Petersburg, Russia, he obtained six grams of meticuIotirs atomic weight determinations in his ruthenium from the portion not soluble in aqua old house, "German Baker's House" in Stock- regia. In recognition of Osann's work, Klaus holm, Ikueden. Scheele discovered chlorine, retained the name ruthenium. moIybdemm, and tungsten in his home apothe- Ruthenium does not tarnish at room caries in Uppsala and Kuping, Sweden. Kla- temperatures, and is not attacked by hot acids or proth discovered zirconium and uranium in his by aqua regia. It is utilized as a hardener for apothecary laboratory in Berlin. platinum and palladium, used to make electrical A handjd of public laboratories during contacts for severe wear resistance. The this time included the Royal Instituiiun in Lon- corrosion resistance of titanium is increased a don, where Davy isolated the reactive alkali hundredfold by the addition of only 0.1% and albline earth metals; Ihe Universi~of ruthenium. Used as a catalyst to split hydrogen Edinburgh where Black and Rutherford sulfide, mthenium oxide may be used to remove investigatedflxed air and nitrogen; the Berlin H,S &om oil refining and other industrial Academy where Marggraf performed his processes. research on alkalis, clays, and sugar beets; the ~colePotjtechnique in Paris, where Vauquelin conducted his research on beryllium and Today it is drflcult for a chemist to chromium; and Lavoisier's laboratory in Le understand the arduous task in the late 17th Petit Arsenal in Pan's, where he studied and early 18th centuries to procure adequute explosives, combustion, cutdrespiration. laboratory facilities. Although in Paris there By the middle 1800s laboraton'es had were some public laboratories that were the been established in mazymore universities. envy of Europe, in other countries the experi- However, even as late as 1860 Crookes menter usually set uphis laboratory in his own discovered thallium in a laboratory on his home and even taught clmses there. Wollaston parents' farm in Brook Green, near London; produced his malleable platinum in his house BoisbCUlClran in 1875 discovered gallium in the laboratory on Cecil Street near the mames in Znborutory in his family's home in the wine London; his later discoveries of palladium and country of Cognac, France; Mangnacfound rhodium were perfumed in his home labor- samarium and gadolinium in the basement atory on Buckingham Street. Smitihsotz Tenm laboratory of his home on Rue Senebier in discovered osmium and iridium in The Temple, Geneva, Switzerland, in 1880; and in I901 an "apartment complex" and his home, near Demargay discovered europium in his home the lhmes. Dalton, based otrt of his apartment laboratory on Boulevard Btvthier, Paris. PERIODIC TABLE

n 1789 Lavoisier turned the concept of "eIementn on its head when he proposed Ithat water was a compound and that hydrogen, oxygen, carbon, sulfur, iron, copper, and 25 other substanceswere the true elements. At this time the listed elements (see Figure 31, page 31) appeared to be a medley of metals, nonmetals,and gases. But scientists are forever searchingfor order and patterns, and as additional elementswere discovered, trends were observed. D6bereiner in 1829 noticed that there were several "triadsn in which the middle element (whose atomic weight lay between the other two elements) had chemical and physical properties which likewise were an average of the other two elements - for example, he pointed out that the equivalent of strontium(42.5) was the

arithmetic mean of calcium (20) and barium . . 1 Figure 51. John Dalton's symbols for the elements, whichstressed the concept of individualatoms anda uniqueatomic weight for each element. (65),and all had similar chemical properties. This pattern that D6bereiner observed depended upon the idea of atomic weight- a concept for which John Dalton was principally responsible. Dalton (Fig. 50) showed how atomic theory could be used to explain the specific weight ratiosin chemical combinations (Fig. 51). The first known atomic weights were listed by Dalton in his notebook in 1805: hydrogen 1 carbon 4.5 oxygen 5.66 sulphur I7 Figure 50. John Dalton, thefounder of am(nitrogen) 4 modern atomic theory. He picturedatoms as featurelessspheres with specificweights. These values appear strangeto the date, Avogadro had shown that two volumes of modem chemist - oxygen should be more hydrogen unite with one volume of oxygen, nearly double the figure given by Dalton. and therefore that water is composed of two However, these atomic weights did not take atoms of hydrogen and one atom of oxygen. into consideration valence, or combining This recognition doubledmany of the atomic power - Dalton believed that water was weights. Hence, on the basis that hydrogen = composed of one atom of hydrogen and one 1.000, then oxygen = 16.026, sulfur = atom of oxygen. These listed values delivered 32.24, and so on. a powehl concept: Dalton substancesmade up of "ultimateparticles" (i.e., molecules) and "ultimate atoms," and he believed that the "specific gravity" (i.e., weight of an atom) was constant fora given atom (element). By 1810 his atomic weights had been expanded to include 36 elements: hydrogen arsenic 42 mte cobalt 55 carbon m-se 40 oxygen Uranium 60 sulphur tungsten 56 phosphorus titanium 40 gold cerium 45 platina Potash 42 silver soda 28 mercury lime 24 copper magnesia 17 Fip52. JUns Jacob Benelius.who iron barYtes 68 discovered seleniumand ceria, and isolated nickel smnti tes 46 silicon, thorium, and zirconium.Berzelius tin d mine 15 accuratelydetermined the atomic weights of lead silex 45 elementsknown at that time, necessaryfor zin: yttria 53 the developmentof the PeriodicTable. bismuth glucine 30 antimony zircone 45 By 1862 de Chancourtoishad devised a These atomic weights were crude,but " telluric screw (helix)" on which he plotted they were crucial to develop the concept that atomic weights as the ordinates and traced a the organization of elements could depend spiral at 45" in sixteen equal portions upon numbers. (arbitrarilychosen on the basis that oxygen's Dalton was colorblind and would atomic weight = 16). As the trace spiraled sometimesappear at meetingswith gaudy red around the cylinder, elementsappeared on socks. He discovered thismalady in himself vertical lines that had similar properties,such and described the phenomenon - "daltonism" as lithium, sodium, and potassium; and is a synonymfor blindness. oxygen, sulhr, selenium, and tellurium. de The atomic weights were refined by Chancourtoishypothesized that "the properties other investigators, and by 1826 Berzelius of substancesare the propertiesof numbers." (Fig. 52) had published a fairly accuratelist of Unfortunately, his contribution was not the atomic weightsof 28 elements. By this imrnediateIyappreciated and was not published in the prominentjournals. tility, malleability, brittleness, andelectro- An andogousapproach wastaken by chemical behavior. Newlands,who in 1864 discovered the "Law Mendeleev's approachwas to arrange of Octaves" - after each series of eight the elements in a table reflectingperiodic elements, similar properties (both chemical behavior of the chemistry in a more and physical) repeated.NewIands proceeded to descriptive manner. Mendeleev's approach organize theelements in families and periods. proved tobe more useful, because itcould be For this brilliant insightNewlands was met generalized- and,as Mendeleev pointedout, with derision;one jokester even suggested that it even predicted new elements! Mendeleev elements mightwell be organized by the himselfstated, "Each law of natural scienceis initials oftheir names! The ChemicaISociety of particular valuescientifically only when it declined to publish his work, but later is possible to draw fromit practical conse- recognized their error and awarded him a quences. . . . especially, whichpermit making Davy Metal in 1887. predictionsthat can be confirmedby experi- The honor of discovering theperiodic ment." Scarcely halfa generation later, his behaviorof the elementswas shared by Men- words would be powerfullyborne out. deleev (Fig. 53) and Meyer(Fig. 54) in 1869. The table published in1871 by Mende- By now 56 elementswere known, and Meyer leev (Figure55, page 62), arranges the elements on the basis of the chemistry ofthe elementsknown at that time. Mendeleevwas so convinced ofthe reality and truthof this arrangementthat he correctedthe valenceof

Figure53. DmitriMendeleev, who devised the PeriodicTable of the elementsusing the format we use today - familiesof elements grouped accordingto their valeme. Figure 54. Lothar Meyer,who shared the plotted atomic weightvs atomic volumeto honorwith MetldeIeev of discerningthe show periodicity with six sections - with periodic natureof the elements.His fonnat incrementsof 16 units in the secondand third of the periodicity (plottinga physical series and incrementsof about46 units in the property,such as atomicvolume, vs. atomic weight), however,was not favored,and in fourth and fifth sections. Meyer proceededto modemtextbooks Mendeleev is generdly show similar behaviorof melting points,vola- creditedwith the discovery. PERlODlC TABLE OF THE ELEMENTS

Fi- 55. Merrbefaev's PeridcTabk, 1871. in c0-w Ms tablc. Merdekgr as& dw the oxide dlmyllium was Ed), h oxideaT idurnwas In& acldthe a& of urmhm w !lo3.TIE IIW aremkplaced art mdIid. 'Di" ww thesymbol h~ didymium. whichwas lam shn m bea mimof m ewh. Merdelmbaldly pmktedat t;mt Lmnewdmm n6r-h i;p6cificpmperties: eh-~. eka dminum, ad&a-sI1jum. Ttm dementswere discovered less than trwenrypl~ later(ce figure 57. pap65)+ Mendeleev's Predicted Elements - Predicted and Observed Properties eka-aluminum - eka-boron - eka-silicon - gallium I scandium I germanium i Predicted Found Predicted / Fwnd Predicted Found

I I

at wt. = 68 j at. wt. = 69.9 at. wt. = 44 i at. wt. = 44 at. wt. = 72 ,at. wt. = 72.3 I I

sp. gr. = 5.9 /sp. gr. = 5.94 I4 low m.p. I m.p. = 30" I

Oxide Ea203/ Oxide Ga203 Oxide Eb2031 Oxide SqO, Oxide EsO, Oxide GeO,

soluble in soluble in with sp. gr. = ; with sp. gr. = 1with sp. gr. = with sp. gr. = acids and j acids and 3.5, not j 3.86, not 4.7 4.70 bases 1 bases soluble in 1 soluble in iI I I 1 alkalies t alkalies I

Volatile / GeCI, with I chloride b.p. = 86" EsCI, j Note: In Mendeleev's predictions, he also included properties of salts and alums, precipitation by hydrogen sulfide, solubilities and reactions of carbonates, atomic volumes of elements and compounds, and spectroscopic analysis. He made only one mistake in his predictions, regarding the volatility of eka-silicon (germanium).

Figure 56. A partial compilationof Mendeleev'spredicted properties foreka-boron, eka-aluminum, and eka-silicon, compared with the observedvalues of the elementsactually discovered. The agreementis amazing.Mendeleev used the chemicalsymbols "Ea"for eka-aluminum,"Ebn for eka-boron,and "Es" for eka-silicon.In this table, the symbol "Es" is not to be confusedwith "einsteinium,"discovered a century later. beryllium from3 (as fixedby Berzelius, who spectroscopic analysis. He had already claimed beryllia had the formulaBGO,) to 2, analyzedaluminum and indium spectra and to give the correctformula as BeO. He further expected spectral lines between the two. assumed (correctly) that the oxide of indium Boisbaudran in 1875 processed several was In@, and that the oxide of uranium was hundred kilograms of "la blende" (zinc UO, . blende, or zinc sulfide) from the Pyrenee Even though Meyer admitted that Mountain region of southern France and Mendeleev's approach was more powerful, followed the extraction and separation of the Mendeleev allowed equal claim of the desired galliumfraction by observation of a discovery. As both were presented with the new violet line at 417 nm. The gallium Davy Medal in 1882, Mendeleev simplyrose hydroxide hethus obtainedwas electrolyzedto and bowed, not feeling comfortable with produce a gram of galliummetal. addressing the audience in English. Meyer Scandium (eka-boron) was discovered then stood and gave the unpretentious words, by Nilson, in conjunction withhis studies of "1 am not Mendeleev. I am Lothar Meyer." the rare earth elements (see Chapter11). He The audience gave a standing, deafening was analyzing a sample of Scandinavian ovation for both scientists. euxenite (a mixed calcium-rare earthtitanate- Mendeleev's predictions realized! niobate-tandate),named for its rare compon- Mendeleev had been so bold as to predict not ents ("good stranger"), and upon separating only the existence of new elements - "eka- someytterbia also obtained anunknown earth boron," "eka-aluminum," and "eka-silicon" whose properties coincided precisdy with (Figure 55, page 62) - but dso the properties those predictedby Mendeleev. of each. Before 15 years had passed, these Germanium was discoveredby Winkler, elementshad been discovered,with incredible in a new sulfide mineral discovered in the accuracy of their properties.A partial list of HimrnelfiirstMine nearby. The new mineral, these predictedproperties, comparedwith the called argyrodite(AhGeS,), was analyzed and found values,appears on page 63 (Figure 56). proved to contain silver and sulfur totaling to Gallium (Mendeleev's predicted eka- 93%. Winkler was able to isolate the new aluminum) was discovered by Boisbaudran, element in 1886, which he named in honor of who used spectroscopy to ferret out a trace his country. At first WinkIerthought he had metal in the zinc mines of southern France. isolated "eka-stibium" (between antimonyand For this analysisBoisbaudran had developed arsensic), and Mendeleevthought perhapsthe methods of spectroscopic analysis, and his element was "eka-cadmium" (between cad- contributions rank him with Bunsen, Kirch- mium and mercury). However, as enough hoff, and Crooks as one of the founders of material had beenisolated for determinationof spectroscopy(see Chapter 10). He reasoned its properties, it became clear that the new that since most minerals had now been element was indeed "eka-silicon* (between completelyanalyzed, there was little hope of silicon and tin). finding a new mineral whose principal The behavior of germanium surprised constituent was one of the undiscovered Winkler, who thought it should combinewith eIements. Therefore, he concluded, the oxygen and be present with titanium and undiscovered elements would be in trace zirconiumminerals. This expectationdepended amounts, and might be best detected by upon the view of the Periodic Table at the PERIODIC TABLE OF THE EL EMENTS (Wendekev, 1 89 1 ) time, where the transition metals were not yet known how many elements should exist recognized as a distinct class, and where between barium and tantalum.This important carbon, silicon, titanium,germanium, zircon- bit of information was not learned until ium, and tin were all lumped into the same - Moseley's X-ray work (see Chapter 14). family. On page 65 the Periodic Table with Anotherobstacle to understandingthe behavior these new discoveriesis presented (Figure 57). of the rare earths had to await Bohr's Huge reserves of were theoretical work in 1922 (see Chapter 14). eventually found in the TriState area of the Thus, Mendeleev had in a short moment in United States (Missouri-Kansas-Oklahoma), 1869 captured the extent to which chemical which were a byproduct (alongwith gallium) theory could be driven: the chemical elements of zinc production in the local mines. When could be organized according to their chemical was recognized as a critical war behavior, but vagaries existed and a motley material, this "useless" substance came into collection of rare earths defied explanation great demand, and for a while this area was despite almostforty more years of toil by the the only sourceof material for semiconductor famous Russian scientist. devices. Filling in the rare earth gap. Mendeleev's Periodic Tables of 1871 and 1891 afforded the basic structure for the organ- Gallium ization of the elements, butthe elementsin the atomic weight range of 140-180 (the rare Ga 31 69.723 earths) were Pwbiesome. Trends in this range [L. Gallia, France] Discovered 1875 made 1ittle sense - atfirst, Mendeleev thought he had correctly placed didymium(actually a 29.8"; $g 2403"; 5.90 mixture of two rare earths), cerium, erbium, Mendeleev had predicted "eka-alurn- and lanthanum (Figure 59, but with the hum" to lie below aluminum in the Periodic discovery of further rareearths he gave up and Table. In 1875 Lecoq de Boisbaudran found left them out ( Figure 57). A further difficulty this element in sphalerite (zinc sulfide) by was found when Brauner discovered(in 1889) methodically concentratinga fraction which the true atomic weightof telIurium was 127.6, exhibited new spectral lines. actually greater than that of iodine - but Galliumis one of three metalk ekments chemical periodicity by now was deeply set in with a melting point near or below room theminds of chemists,and it was accepted that temperature(30" C). Gallium cannot be stored atomic weightwas obviously not the ultimte in glass containers,because it expands when criterion for periodicity. freezing and cracks the glass. Gdlium is an In Mendeleev's last Periodic Table, extensivelydispersed element in nature, and presented in 1902, he had added a column of mineralswith specificstoichiometries are rare. inert gases (see Chapter12), but he avoided Instead, mostof the galliumis found in trace the rare earths. Brauner was more ambitious quantities beside other elements, and is (see Figure 58, page 67). An attempt by him recovered as a byproduct of other refinery to create orderin the 1902 Periodic Table was productions, notably zinc. Gdlium is used in noble but artificial. Oneof the difficultiesin semiconductors;gdlium arsenide can convert understanding this gap was that it was not electricity directlyinto coherentlight. PERIODIC TABLE OF THE ELEMENTS (Brauner. 1902)

Figure 58. Bramr'sPeriodic Table of the elements, 1902. By this date a whole new family hadbeen recognized - the inert gases.Brauner bravely includeda number of rare earthsinan arbitrary, but imaginative design. Elements known but not includedin the table are dysprosium,polonium, actinium, and radon. In this scheme he predicts98 elements throughhum (6 too many!). element itself. Winkler named the element Scandium germanium. Comparison of its properties with Sc 21 44.9559 Mendeleev's published prophesyingdata gave [L. Scandia, Scandinavia] convincing proof his new element was indeed Discovery: 1876; crude metal 1937; eka-silicon. pure metal 1960 Germanium is used as a semiconductor mp 1541"; Izp2836"; s~_et2.99 material. The first transistor was prepared Mendeteev had predicted the existenceof from germanium in 1947 at BeH Laboratories. "eka-boron" between calcium and titanium. Transparent to infrared light, germanium and Lars Fredrik Nilson stumbled upon this its oxide are used in optical equipment such as element while examining an extract of erbia sensitive infrared detectors. With a high index from euxenite and gadolinite. Following of refixtion, germanium is used in wide-angle Marignac's procedure, he obtained some pure camera lenses and microscope objectives. ytterbia, and in addition a feebly basic unknown earth. This earth's properties corresponded to those anticipated by Mendeleev, The Periodic Tdle wasdeveloped from and was rapidly accepted as the sought eka- chemical behavior of the elements, which boron.The metallic element was first prepared exhibits us@l and consistent trends. Pwsical in 1937 by Fischer, Bmger, and Grieneisen. behavior is a different stoty. Melting points, Scandium is expensive and rare; it exists for example, decrease down the alkali metal in higher levels in the sunthan on earth. The family but increase down the halogens. The first pound of this metal was obtained in 1960. three metals with low melting points (cesium, Scandium iodide added to mercury vapor gallium, and mercury) are not grouped lamps produces a bright light source resem- together but are scattered about the Periodic bling sunlight. Table. Transition elements (in the d-block) a to have interesting and color and magnetic properties. Metal ions that have Germanium empty d subshells (such as SC+~or TP4)or Ge 32 72.61 jilled d subshells (such as Zn+') are colorless. [L. Germania, Germany] The colored ions include Mn" (pink), CP6 Discovered 1886 (yelfow/orange), CP3 (green), Fe+3 (red), mp 937.4"; Izp2830"; spsr 5.32 Fe+2 (green), Ni" (green), and Cd2(blue). Mendeleev had predicted "eka-silicon" to O@n the hydrated and anhydrom species are fill a gap between silicon and tin in the cobred diflerently (such as CO(H,O),+~,pink, Periodic Table. Clemens Winkler discovered CdZ, blue). this prophesied element by investigating The middle of the Jirst d-block includes argyrodite, a mineral from the Himrnelfirst ferromagnetic elements (iron, cobalt and mine near Freiberg, Getmany. When his nickel), but not the second and third d-blocks. routine analysis did not account for all the mere exists one more ferromagnetic metal, in elements, he concluded that the ore must the middle of the lanthanides Fblock) - contain an unknown element. In 1886 he gadolinium (which loses its magnetism at I6 7. succeed in isolating the sulfide, and then the 10. THE BUNSEN BURNER SHOWS ITS COLORS

he alchemists had known since the of each. Alter had the foresight to predict that 1500s thatheated substances imparted spectroscopic analysis would even somedaybe Tvarious colors to a flame. In the 1700s used to identify the elements in stars. Marggraf (Fig. 59) demonstrated that sodium In 1859 Robert Bunsen and Gustav salts could be differentiated from potassium Kirchhoff invented the flame spectroscope (Fig. 60), an instrument that allowed the identification of elements by their emission spectra. This instrument consisted of three parts: (1) a flame andcollimator which would allow light in a narrow band from the incandescent sample; (2) a prism which could be rotated to admit and pass on various wavelengths of light; and(3) a telescope to observe the color being emitted by the gIowing

Figure59. AndreasMarggraf, who recognizedalumina in clay andthat magnesiawas distinctfrom calcium compounds.He furtherdistinguished between potash and soda. salts by the former's yellow color and the latter's purple hue. Fraunhofer in 1818 invented the spectroscope which aIlowed the observation of different light wavelengths (colors) and the exact measurement of these Figure60. The flame spectroscope,invented wavelengths. Careful observation allowed by Bunsen andKirchhoff, which was used to Talbot in 1834 to differentiate lithium from identify knownelements andto identify new strontium, even though each both gave red elements. flames(lithium is carmine; strontium is sample. This optical instrument allowed the scarlet). Soon it was recognized that each very precise measurement of wavelengths of element exhibited its own unique spectrum: light that were being emitted by samples David Alter in 1854 unequivocally stated that heated to incandescence in the flame. Bunsen each element had a characteristic independent (Fig. 61), the perfecter of the Bunsen burner, spectrum, and an alloy of two metals in an and Kirchhoff (Fig. 62) were professors at electric spark would exhibit the spectral lines Heidelberg University, and together they burned pyrites (sulfide ores).He studied thallium compounds extensively and discovered they were extremely poisonous. The codiscoverers ofindium wereReich and hisassistant Richterat the Freiberg School of Mines (Fig. 63). Reich published the results jointly with Richter, but later regretted this decision, because Richter attemptedto claim full credit for the discovery.

Figure61. RobertBunsen, bestknown for Ms inventionof the Bwenburner. founded the scienceof spectroscopic analysis. Bunsen and Kirchhoffin 1860 studied a concentrateof mineral water (from Diirkheim) using their spectroscope.The usual lines could be observed of sodium,potassium, lithium, calcium, and strontium.However, two new blue lines were observed, which they attributed to a new element and which they Figure62. GustavKirchhoff. who with Bunsen inventedthe spectroscopeand named cesium from the color.A few months discovered cesiumand rubidium. later they observednew deep red spectral lines of a new element they named rubidium. The In 1863 Reich began a search for elementsthemselves were isolated in the same thallium in zinc ores from the Himmelfiirst laboratory from lepidolite (an attractive Mine. It will be recalled (Chapter 9) that lavendermica) in 1862 (by Bunsen) and 1882 germanium was discoveredat this famous (by Setterberg), respectively. school and mine. Reich wantedto conducta Sir William Crooks, who shared with spectroscopicanalysis, but he was colorblind Bunsen,Kirchhoff, and Boisbaudranthe honor and preferred to entrust the examinationto his of establishingthe scienceof spectral analysis, assistant Richter. Upon placing a platinum was studyingsome waste froma sulfuric acid loop of zinc blende ore in a flame, Richter plant at Tilkerode in the Han Mountains, observed an intense indigo color which was central Germany. Analyzing the residuesfor obviouseven withouta spectroscope.The new selenium and tellurium, he observed a new elementwas named indium. intense green line,which he attributed to a Reich and Richter were able to easily new element he named thallium for "green prepare the elementalmetal by reduction of the branch." oxide with charcoal. They found that this To isolatea sample of thallium, Larny in metal was adrnixturedwith zinc prepared from 1873 extracted the sulfuric acid prepared from Diirkheim, Germany, and observed two new blue lines which they attributed to a new element they named cesium. Carl Setterberg separatedthe metallic element electrolytically in Bunsen's laboratoryfrom lepidolite(a mica, a mixed potassiumalkali aluminum silicate, where the potassiumis occasionallysubstituted by cesium and rubidium)in 1882. Cesium is the most reactive metallic element, explodingviolently with water. Cesiumis used as a "getter" in electrontubes, scavenging residualoxygen. With the second lowest melting point (28" C), cesium is a Figure 63. Laboratory at Freiberg School of liquid in a warmroom. This eIementis used as Mines,Germany, where the de Elhuyar an atomicclock, accurateto 5 seconds in300 brothers (isolated wren) and del No years. (discovered vanadium) mined. Reich and Richter (discoveredindium) and Winkler (discoveredgermanium) taught here. Rubidium the Mine and could be isolated more easily Rb 37 85.4678 from the zinc itself than from the ore. [L. rubidus, deepest-red, Generallyindium is found in geologicallyold from lines in spectrum] zinc blendes,whereas newer geological forma- Discovered1861, element isolated 1863 tions are more likely to hold germaniumand 38.8"; 686"; 1.53 gallium. Robert Bunsen and G. R. Kirchhoff in With the new spectroscopic method,an 1861 detectedthe elementrubidium by its red invaluable tool was now available to find a spectral linesin Diirkheim spring water. Two wide array of new elements. In fact,this years later they separated the element techniquewas responsiblefor the discoveryof electrolyticallyfrom lepidotite (same as for a new entire family of elements.This story is cesium, see above). The burner which issued told in Chapter 12. a colorlessflame, which Bunsenhad designed in 1854-55,made this discovery possible. Rubidium ignites spontaneouslyin air. With a melting point of 39" C, rubidium Cesium would melton a hot sidewalk. Rubidiumis Cs 55 132.9054 used in photoelectrical cells.This element is dispersed through nature, mixingwith the [L. caesius, sky blue, other dkali metals, and does not form from lines in spectrum] compounds with specific stoichiometries. Discovered1860, elementisolated 1882 Small quantities of rubidium are found in 28.4", hp669.3"; 1.87 certain foods, includingcoffee and tea; trace Bunsen and Kirchhoffin 1860 analyzed quantitiesmay be requiredby living systems. by flame spectroscopy themineral water of not form a protective oxide coating as do other Indium elements such as aluminum and copper. In 49 114.82 Because of its tendency to crumble into [from indigo spectroscopic line] crumbs of black corrosion over a period of Discovered 1863 years, thallium as a metal hasno commercial 156.6"; !zp 2080"; 4.93 application. Soluble thallium salts are poison- Searching for thallium in some Freiberg, ous; tasteless and odorless, they were formerly Germany, zinc ores, Reich and Richter used as rodenticides and insecticides. Thallium observed an intense bIue color when a sample bromide-iodide crystals are used in infrared of zinc blende (zinc sulfide) was heated in a optics. Bunsen burner (1863). These lines did not coincide with those of cesium, and the blue color was attributed to an new element named From Agricola's time until the 1800s, from the indigo spectral color. They found the chemistry and mineralogy were united disci- new element was infused with zinc metal plines. In fact, many of the chemists of these smelted from the ore, and discovered how to times were also mirteralogists who were isolate it. Until 1924, a gram constituted the makingtheir chemical discoven'es through the world's supply of elemental indium. analysis of ores. Toduy several excellent Indium is a dispersed element in nature, mineralogical collections of historical value procured principally from zinc ores. Indium is may be viewedat famous museums, such as the used to make low-melting alloys; indium is Musee de Mintralogie at the ~coledes Mines particularly important in the production of in Paris and the Werner Museum at Technische optical devices that require a glass-to-metal UniversitutBergahdernie Freiberg, Germany, seal. where several elements were discovered Lepidolite, whichpgured in Ihe history of the alkali metals rubidium and cesium, is a Thallium form of mica. Mica is a flaky mineral, made up TI 81 204.383 of an intricate aluminum silicate moleczdar [Gr. thallos, green twig, network interspersed with alkali ions. In micas from lines in spectrum] the alkali ion is locked up chemically and Discovered 1861 cannot be extracted easily in aqueous soltttion, as it can from alkali halides such us halite or 303.5'; hp 1457"; 11.85 lllg so sylvite. Lepidolite, a pretty lavender mineral, Examining some residues from a sulfuric has the formula K(Zi,AI),[AISiO,O, JKOH), acid plant in the HanMountains, Germany, where rubidium and cesium can replace Sir William Crookes observed a bright green potassium ions to the extent of a few percent. line in the spectroscope mixed with the fami- Minerals with speciJic stoichiometries of liar bands of selenium (1861). He christened rubidium do not occur in nature. By contrast, this element thallium for its spectroscopic line. cesium can occur in pollucite, a zeolite with Larny prepared an ingot of thallium that he the formula Cs~lJi,Ol2*H,O.Zeolites are presented the following year to the AcadCmie hydrated alminum silicates which can be des Sciences. repeatedly hydrated and dehydrated without Thallium, whose oxide spalls off, does losing their structure. 11 THE RARE EARTHS

he separationand identificationof the Basenis,"Scheele and de Elhuyar studied this rare earth elementstested the skills and mineral, expectingto find tungsten, but found Tpatience of the best chemists of the none. Berzelius, Klaproth, and Hisinger all nineteenth century. The first hint of the riches examined this mineral, searching for yttria, of this group of elements lay in a black sincethey reasoned that previous investigators, mineral found in the Ytterby Mine, near not aware of this new element, might have StockhoIm. This heavy rock, first cdled missed it. Instead, theydiscovered a new earth "ytterbite," was discovered by Lieutenant Carl in 1803 which was named cerium after the Axel Arrhenius, a Swedishchemist and miner- asteroid recently discovered (Ceres). The alogist. mineral, named "cerite," is now known to In 1794 Johan Gadolin (Fig. 64), profes- have the formula(Ce, C&OiO,),(OH, F),, but sor of chemistry at the University of Abo, as with all rare earth minerals can be 1' : : , .- admixturedwith these scarcer elements. Soon .. .=. .I ._ . cerium was discoveredin additional minerals - allanite from Greenland and yttrocerite from Sweden. Theseminerals have the formulas(Ce,Ca, Y),(AI ,Fe),(SiO,),(OH) and (Ca,Y ,Ce)F,, respectively.

><-, .#' Figure 64. Johan Gadolin,who discovered yttria. He conducted a thorough studyof the rare earth mineralsfrom Ytterby, Sweden.

FinIand,made an exhaustive analysis of the new mineral and found silica, glucina (beryllia), iron, and a new "earth" (oxideof an element) he named yttria. Ytterbite is now Figure 65. Carl Mosander, who discovered known as "gadolinite" (a mixed rare-earth lanlhana, didymia, erbia, and terbia, mineral with the formula wFeBqSi,O,,, Mosanderwas the first to appreciatethe where RE= Y, Ce, and other rare earths). complexityof the rare earths when he Another heavy mineral was found in the extracted befirst two rareearrhs from ceriumand the latter two rare earths from Bast& Mine Riddarhyttan, Vestmanland, at yttria. Sweden, by Cronstedt as "the heavy stone of The two new earths yttria and ceria proved to also hold holmia and thulia (Cleve, proved to be composed of perplexing mixtures 1879), and the holmia furthergave dysprosia of yet further elements. The first hintof this (Boisbaudran, 1886). Mosander's didymia complexity was gained by Carl Gustav further gave samaria (Boisbaudran,1879), Mosander (Fig. 65), one of Berzelius's and yet again gadolinia (Boisbaudran,1886). assistants. Mosander in 1839 treated cerium Although Boisbaudran(Fig. 66) named gado- salts in nitric acid; the cerium oxide remained linia, it was identical to a rare earth that insoluble while in the extracta new earth was Marignacin 1880had discovered insamarskite found. He named this new substance lanthana, (Marignac gavehis consent for this name). meaning "hidden." The same year Axel Boisbaudran'sdidymia was then separated into Erdmann, one of Sefstriim's students, found praseodymiaand neodymia (Welsbach, 1885). lanthana in a new Norwegian mineral,named Europa was extracted fromsamaria (Demar- "mosandriten (a mixed calcium-cerium gay, 1901). Finally, lutetium wasseparated titanium-silicate). FriedrichWijhler, one of from ytterbia (1907). Credit for this last Mosander's closest friends, kept nagging discovery is shared by Georges Urbain of Paris Mosander to publishhis work on tanthana, (who gave it the accepted name), Auer von but Mosander hesitated. Soon the reason for Welsbach (who named it cassiopeium), and the delay became apparent when in 1841 when Charles James ofNew Hampshire (whohad a new brown earth (pure ceriaand lanthana prepared a large amountof pure lutetium at the were both white) was extracted from lanthana. time of Urbain's announcement). This new earth was named "didymia," named Because of their separation difficulties, so becauseit wasan "inseparabletwin brother the rare earths were originally thoughtto be of lanthana." The new earth imitated the quite properties of cerium and lanthanum salts so closely that only with repeated crystallizations could it be separated. Mosander then turned to yttria, which he likewiseshowed in 1843was composed of yet two additional substances by fractional precipitationwith ammonium hydroxide:erbia (rose-colored)and terbia (whitish). Mosander's experiments wereonly the beginning - other chemistsproved that yttria and ceria held twelve additionalrare earths! Yttria yielded the "heavyrare earths": terbia, erbia, gadolinia, ytterbia,dysprosia, holrnia, thulia, Iutetia. Ceria surrendered the "light rare earths": samaria, europia, praseodymia, and neodymia Figure 67 (page 75) shows how Fiyre 66. Lecoq de Boisbaudran,who each was further separated and isolated. In discoveredgallium, samarium,and 1878 Marignacseparated ytterbia from erbia. dysprosium.With Bunsen, Kirchhoff,and Crookes, he is regardedas one of the Nilson (see Chapter9) then separatedscandia foundersof specuoscopicanalysis. from ytterbia in 1879. The erbia fraction (Benelius, Hisinger, Klapr as mercury or lead, which have been known for centuries. Thulium, the leastcommon rare Ceria earth, is actually more common than gold. In nature rare earths are dispersed - while such La Ce elements as mercury, lead, and gold have been concentrated, giving the false appearance of greater overall abundance. Suchproperties as La melting points of the metallic rare earths and Di their oxides had to await isolation of pure material. Most rare earths were not isolated in pure form until the 1950s, when ion-exchange Bois., sin Di separation and metallographic reduction techniques were developed by Frank Spedding at Iowa State University. The major question concerningthe rare earths facing the chemists of the early twentieth century was: Exactly how many rare earths were there? Chemists wondered how many more elements would be separated from Heavy rat the score of variably colored oxides already I eor(hs (IY t t ridGadoLin)known. Brauner had predicted perhaps 20! (Fig. 58, page 67).The definitive answer to this question would have to wait until Tb/ Er Moseley's X-ray work (Chapter 14).

Yttrium (SeeChapter 3, page 22) Cerium Ce 58 140.12 [L. Ceres, goddess of agriculture] Figurc67. Historical outlineof the discoveryof the Discoverv: oxide 1803; impure metal 1875; rare earths.Key: Mos.=Mosander, Bois.=Boisbaudran;Mar.=Marginnc; pure metal ( > 99%)1944 Wels.=Wetsbach;Dem.=Dernqay; Clc.=Clcve; 798"; 3443"; 6.77 Nil.=Nitson;Urb.=Urbain; Jam.=James. Originally, WiIhelrn Hisinger, Swedishmineralogist the terbia and crbia nameswere reversed.Gadolinin and geologist, was owner of the famous was namedby Boisbaudrnnbut badbeen previously Riddarhytta property, where the Bastniis mine discoveredby Marignacby separationFim sammkite."Di"="didyrnium," n mixtureof Pr and yielded a curious mineral called cerite. Nd, was originally thoughtto be a singlerare earth. Because of its high density, it was called "the tungsten (heavy stone) of Bastniis."Klaproth, Sefstriim's assistants, discovered Ianthana in a Hisinger, and Berzelius in 1803 investigated new Norwegian mineral,named "rnosandrite. " cerite, searching for yttria. Instead, they found Since lanthanum behaves as a rare earth, it a new element, which was named cerium in could not be prepared in pure form until rare recognition of Ceres (the first asteroid, earth separation techniques were developed. discovered two years previously). W. F. Lanthanum is used in carbon lighting Hillebrand and T. H. Norton prepared the applications, particularly by the motion picture metal in 1875 by electrolyzing molten cerous industry. Lanthanum oxide (L%03) increases chloride. the resistance of glass to alkalis, used in Cerium is the most abundant rare earth, special optical glasses. Lanthanum is one of and the second most reactive rare earth; it the more reactive rare earth elements, slowly decomposes in cold water. Cerium is combining directly with carbon, nitrogen, the main constituent of "misch metal," a boron, selenium, silicon, phosphorus, sulfur, pyrophoric alloy which when struck liberates and the halogens; thus, lanthanum is an showers of sparks - and thus is used in effkctive scavenger for gases in molten metals automatic gas-lighters and cigarette lighter and their refining. MetaIlic lanthanum oxidizes flints (Misch metal is a mixture of light rare rapidly in air to give a white oxide. The earths, with typical ratios of 50:25:18:5:2 greatest use of lanthanum (mixed with other Ce:La:Nd:Pr:other). The white oxide CeO, is rare earths) is for molecular-sieve catalysts for used in incandescent gas mantles and a cracking petroleum. Misch metal, used in hydrocarbon catalyst in self-cleaning ovens. cigarette lighter flints, is composed of 25% Cerium oxide is replacing rouge (iron oxide) lanthanum. as a polishing agent for lenses and television faceplates, because it is much faster. Cerium, as well as other rare earths, is used as a Praseodymium molecular sieve catalyst in petroleum refining. Pr 59 140.9077 [Gr. prasiosdidymos, green-twin] -: -: oxide 1885; impure metal 1931; Lanthanum pure metal 1952 La 57 138.9055 931"; hp 3520"; 6.77 [Gr. lartthanein, to be hidden] Ceria and yttria, the first two rare earth Discovery: oxide 1839; crude metal 187 oxides prepared, proved to consist of a pure metal 1952 bewildering array of no less than thifieen 918";Bp 3464"; 6.14 additional rare earths. The first to tackIe this Carl Mosander, one of Berzelius' complex problem was Carl Gustav Mosander, assistants, first recognized the complexity of one of Berzelius's assistants. First, in 1839 he the rare earths. He was the first to show that extracted lanthana from ceria. Then, in 1841 Klaproth's ceria and Gadolin's yttria actually he further treated lanthana with dilute nitric held additional rare earths. The first " hidden" acid and extracted a new brown oxide, which rare earth (lanthma)was separated from ceria he named didymium because it was a "twin in 1839 by extraction with dilute nitric acid. In brother of lanthanum." Mosander carefully the same year, Axel Erdmann, one of showed that the original pastels of yttric and cerous salts were in fact due to contamination oersteds, exceeds the well-known samarium- of didymium salts. Many thought didymium cobalt magnetsin strength. Neodymium and was again simplya mixture of rare earths. In praseodymiumare the third and fourth most 1882 Brauner spectroscopically examined reactive rare earths;they give oxides which didymia and saw absorption bands from two spa11 off, exposing more metal. The oxide of elements. Welsbachseparated the two in 1885, neodymium, Nd203,is light blue. which he named praseodymia(green dymia, the color of the oxide) andneodyrnia (new dymia). Samarium There actually exist two common oxides Sm 62 150.36 of praseodymium: Pr,O,,, the common oxide [Smrskite,a mineral] which is black;and Pr203, the green oxide Discovery: oxide 1879; crude metal 1937; which forms initially on oxidizing praseo- pure metal 1953 dymium. This latter greenoxide is the one 1074"; ha1794"; so 7.52 WeIsbach noted. The black oxide was Lecoq de Boisbaudran, believing in 1879 originally thoughtto have the formulaPtO,. that Mosander's didyrnia was not one oxide, Praseodymium is used in misch metal added sodium hydroxide, and another earth and in carbon arcs. Didymium (praseodymium precipitated beforethe didymia. He named the and neodymium) is used to color welder'sand earth sanrariaafter sarnarskite, named after The glassmaker's goggles. resulting lenses Colonel Samarski, a Russian mine official. filter out the yellow light of glass very Samarium is used in misch metal and in efficiently. carbon-arc lighting.SmCo, hasbeen used to make a new permanent magnet, which until recently, was the strongestknown - over 25 Neodymium megagauss-oersteds.Samarium oxide (Sm,03, off-white in color) is used in optical glass to [Gr. neos-didymos,new-twin] absorb infrared, and can act as sensitizersfor Discovery: oxide 1885; impure metal 1925; phosphors excitedin the infrared. Samarium pure metal 1944 oxide is a catalyst in the dehydration and 1021"; hg 3074"; 7.01 dehydrogenationof ethyl alcohol. Neodymiumwas the other componentof ~osander'sdidymia that was separated by Welsbach. Neither praseodymium nor neodymium has been resolved into further oxides. Eu 63 151.96 Neodymium is used in misch metal and [Europe] in didymi&. Neodymiumcolors glass delicate Discovery: oxide 1901; crude metal 1937; shades of pure violet through wine-red to pure metal 1953 warm gray. Light transmitted through this hp822"; 1527"; g! gr 5.24 glass shows very sharp absorption bandsand is EugEne-Anatole Demar~ay,through a used to calibratespectral lines in astronomy. A Iaborious sequence of crystallizations of neodymium-iron-boron compound(Nd,Fe,,B), samarium magnesium nitrate, in 1901, was exhibiting a energyproduct of 50 megagauss- able to separate a new earth. He named the new element europium. disappears) just at room temperature (the only Europium is the most reactive of the rare other ferromagnetic elements are iron, cabalt, earths. It oxidizes rapidly in air and resembles and nickel). The oxide Gd,O, is white. calcium in its reaction with water. Europium can ignite if scratched with a knife. Europium oxide (Eu,O,, white in color) is extensively Terbium used as the red phosphor in color television Tb 65 158.9253 tubes. The oxide Eu,O,fluoresces intense red [ Ytterby, SwedenJ in ultravioiet light. Discovery: oxide 1842; crude metal 1937; pure metal 1953 1356"; & 3230"; 8.23 Gadolinium Mosander, who had shown ceria was Gd 64 157.25 composed of additional rare earths, studied [Gadolinite, a mineral] yttria in the same manner. He separated out Discovery: oxide 1880; crude metal 1935; two additional earths in 1842, which he named pure metal 1944 erbia (yellow) and terbia (rose). This work 1313", Ihp3273"; so 7.90 was confirmed by Delafontaine, Marignac, Boisbaudran, after discovering sarnar- Smith, Cleve, and Boisbaudran. For some ium, isolated yet another earth from didymia reason the names erbia and terbia were in 1886. This was identical to the rare earth interchanged, so that the yellow (or brown which Marignac had separated from sarnar- when pure) earth now is terbia. skite in 1880. Sarnarskite is a radioactive, Terbium oxide (Tb,O,, chocolate-brown glassy-black, brittle mineral with the formula in color) can be used as an activator for green (Y,U,Fe),(Nb,Ta,Ti)O& where Y can be phosphors in color television tubes.Sodium other heavy rare earths. Marignac consented to terbium borate is used as a laser material. Boisbaudran's suggested name of gadolinium, aRer the mineral gadolinite, which has the formula ~FeBqSi,O,,,and which was the Dysprosium original mineral analyzed by Gadolin. Dy 66 162.50 Gadolinium is the "transition" element [Gr. hard to reach] between the heavy and the Iight rare earths. Discovery: oxide 1886; crude metal 1937; Indeed, "gadolini te" is a very appropriate pure metal 1952 name for the mineral which can contain both 1412"; hp2567"; st,nc 8.55 heavy and light rare earths. In 1886 Lecoq de Boisbaudran separated Gadolinium has the highest thermal yet another rare earth from holmia - neutron capture cross section of any known dysprosium - by fractional crystallization, element. Gadolinium has been used in making first with ammonium hydroxide and then with gadolinium yttrium garnets, used in micro- potassium sulfate. He found the following wave applications. It has used in making phos- fractions in this order: terbia, dysprosia, phors for color television tubes. Gadolinium is holmia, and erbia. Never having much unique for its high magnetic moment and its material to work with, Boisbaudran did most Curie temperature (at which ferromagnetism of his research on the mantle of his fireplace! Dysprosium has found limited use in laser materials. Its high thermal neutron Thulium absorption cross-section and high melting point Tm 69 168.9342 suggest nuclear applications. The oxide Dy,O, [Thule,Scandinavia] is white. Discovery: oxide 1879; cmde metal 1937; pure metal 1953 1545"; hg 1950"; 9.32 Thulia was the second rare earth, in Holmium addition to holmia, that Cleve isolated from Ho 67 164.9303 erbia. [L.Nolmia, Stockholm) Thulium is the rarest of the rare earths - Discoverv: oxide 1879; crude metal 1939; until a few years ago, the elemental form was pure metal 1953 not obtainable at anyprice. The oxide Trn,03 n~ 1470•‹,hg 2700";st,er 8.80 is white. The erbia remaining after the removal of ytterbia was still further fractionated in 1879 by Per T. Cleve, who obtained two additional Ytterbium rare earths: holmia (named for his native city) Yb 70 173.04 and thulia. [Ytterby , Sweden] Holmium has found few uses. It has Discovery: oxide 1878; crude metal 1937; unusual magnetic properties. The oxide Ho2O3 pure metal 1953 is yellow. mp 818"; 1196"; 6.90 Marignac in 1878 isolated an additional earth from erbia. This earth was prepared by extracting erbia with water - for the rose Erbium fraction he retained the name erbia, and for the Er 68 167.26 colorIess fraction he gave the name ytterbia. [ Ytterby , Sweden) Ytterbium can be used to improve the DL!:oxide 1842; crude metal 1934; mechanical properties of steel. The oxide pure metal 1953 Yb,O, is white. 1529"; hp.2868"; st, 9-07 Erbium is the sister rare earth to terbium, both of which Mosander isolated from yttria in Lutetium 1842. Subsequently, erbium was isolated into Lu 71 174.967 five additional rare earths, plus scandium! [Lutefia, ancient name for Paris] Erbium added to vanadium lowers the Discovery: oxide 1907; crude metal 1937; hardness and improves workability. Erbium pure metal 1952 oxide (Er,O,, pink in color) has been used as 1663"; lg 3402"; 9.84 a fast pigment in glass and enamel, and is the The last natural rare earth to be best pink colorant for ceramics. discovered was lutetium, obtained by Georges Urbain in 1907 by fractional crystallization of ytterbium nitrate from nitric acid. Ytterbium and lutetiumwere identical with"ddebaran- mine in Yfterby- the originalyttrium, as well ium" and "cassiopeium," respectively,discov- as erbium, terbium, and ytterbium. ered independentlyby Auer von WeIsbach. The growing list of rare earths led to The credit of discovery of lutetium is also conJirsing claims, counterclaims,and repudia- sharedwith Charles Jamesof New Hampshire tions. me major element of contention was who had prepareda large amountof lutetium element 71,lutetium, which was independently by the time or Urbain'sannouncement. discovered by Georges Urbain, Auer von Lutetiumis one of the mostdifficult rare Welsbach,and Charles James. The German earths to isolate. Possiblefuture uses include and Austriar~scient@c communities strongly catalystsfor cracking,alkylation, hydrogen- resisted the claim by Urbain. The suspicion ation,and polymerization.The oxideLu,O, is was strong that Urbain, as a member of the white. Lutetium tantalate (LuTaO,, with a International Commissionon Atomic Weights, specificgravity of 9.75), is the heaviestwhite exerted unduepressure to have his claim and substanceknown. name acceptedfor element 71. Instead, the Austro-Gemscientists persistedin naming element 71 "cassiopeium." Auer von Welsbach Chemically,the "rare earths" include not named the other element separated from only elements58-71 but alsoyttrium (39)and ytterbium "aldebarcutium." me third codis- lanthanum (57). The lanthanidesare divided coverer of lutetium, CharlesJames, clearly into "light"rare earths, behaving like cerium should have received equal credit, because he had already accumulateda large supplyby the (l& half in Periodic Thble),and the "heavy" rare earths, behavinglike yttrium (righthalf). time of Urbain's announcement, but he gra- This trend is due to the larzthunidecontraction, ciously and professionally acceptedUrbain 's which shrinkr the atoms as one progressesto claim. James had worked out detailed and the right. Hence, cerite includes cerium & mcient methods of separating not only lute- lanthanum, praseodymium,samariwn, and/or tium, but all of the rare earlhs. Claim for element 61 (promethium) europium. Gadolinitehas yttrium & dysprosium, terbium, holmium, erbium, thulium, include "illinium"by J. A. Harris and B. S. ytterbium, and/or lutetium. Gadolinium,mid- Hopkins of the University of Illinois and yorentium" by L. Rolla and L. Fernandes of way in the series, can occur in eithermineral. of ?he lanthanidesshare a valence of 3 and the Universityof Florence, both which were have a strong aflnityfor oxygen. Mixed rare- isolatedfromnatural sourcesand later shown earthJTuoridesare burned in cahon electrodes to be erroneous.A later claim by Ohio Stae to create the intensesunlike illuminationused University for "cyclonium" obtained from a cyclotron was inconclusive. The undisputed by motionpicture projectorsmi searchlights. Europium, gadolinium,erbitun, dysprosium, discovery of "promethium"(see page 106) in 1941 wasfinally madein thefission products and samarium have the highest thermal neutron absorption properties inthe elements; from uraniumin an atomicpile. Twoprincipal sources currentlyaist for yttrium by contrast is almost transparent to the rare earths: California and China. The thermal neutrons and is stable even in the presence of liquid uranium. American mine at Mountah Pass CA yields Four elementsare namedflomthe famed mainly the lighter rare earths; the Oriental source containsmore of the heavierones. 12. THE INERT GASES

ecause of his experimental skill and engaged in the study of the molar volumes of careful measurements, Cavendish in gases, and accordingly had needto measure 1785 had actually discovered the first very accurately the densities of hydrogen, inert gas - argon. He described how he oxygen, and nitrogen. Although he obtained passed an electric spark through a mixture of consistent results for the first two gases, the "dephlogisticatedair" (oxygen) and "phlogis- values he obtained for nitrogen varied depend- ticated air" (nitrogen) to form niter, and he ing upon the source. The value for nitrogen he found that part of the "phlogisticated air" obtained from ammoniawas about $5 % lower failed to react and remained as a gaseous than that obtained from the atmosphere. residue. His precise measurements even Deeply puzzled, he even wrote Nature, asking allowed him toquantitate the residue: 1/120 of the readers for any possible explanations. the atmosphere. This keen observation lay Possible reasons included contaminationwith dormant for a century until Lord Raleigh oxygen or hydrogen, or even an allotropic began his experiments on the atmosphere in form of nitrogen N,, analogous to ozone 0,. 1882. He turned to the experimental abilities of Sir John William Strutt, Lord Raleigh (Fig. William Ramsay (Fig. 69). 68), was professor of physics at the Cavendish Laboratory at Cambridge University. He was

Figure69. Sir WiiliarnRamsay, who discovered the inert gases neon, argon, Figure 68. John WilliamSuutt, Lord krypton, ~JKIxenon. All of these gases were Raleigh. During a molecularweight preparedfrom the atmosphere. Removing determinationof nitrogen,he noticed a all the nitrogen, oxygen, carbondioxide, difference betweenatmospheric nitrogen and and water left residualargon, constituting that obtained from inorganic compounds. 1%of the original atmosphere. Fractional This observationled to the discovery of he distillationof this argonpve minute admixturedargon. amounts of the other inen gases. Figure7O.Ramsay's apparatus for isolating argon from the atmosphere. The constituents of the atmosphere were removed ir~lividuallyby passing them over various reactants: oxygen over hot copper 0, nitrogenover hot magnesium (G), carbon dioxide over soda lime 0, and water over .phosphorus . pentoxide (H). Ramsay passed atmospheric nitrogen xenon. Argon constituted about 1% of the over incandescent magnesium (to form atmosphere.No wonder Cavendishhad found magnesium nitride) repeatedly until a a respectableresidue that would not react! consistent volume of residual gas remained Actually, argon had not been the first (If80of the original volume)(Fig. 70). Both inert gas observed spectroscopically.In 1868 Ramsayand Raleigh believedthis might be a Janssen had traveled to India to make a modification of nitrogen, but its spectrum spectroscopic studyof the sun'schromosphere showed red and green lines never before during a total eclipse. He saw an intense observed. Crooks himself performed a yellow line which was shifted from the thoroughstudy of the gas and established that it was not anyfonn of nitrogen. Finally Ramsay and Raleigh stumbled onto the truth: Ramsayin a letter to Raleighin 1894 asked, "Has it occurred toyou thatthere is room for gaseous elementsat the end of the first column of the Periodic Table?" They concludedthat they hadisolated a new, inert elementalgas. They announcedtheir discovery the sameyear at a meeting of the British Association, and namedthe element at the suggestionof the for Chairman - argon the Figm 71. Sir Norman Lockyer, who lazy one. Boisbaudranpredicted that argon fromthe yellow line in the sun's might belongto a wholenew family of inert spectrum, that a new element hadbeen elements, and he even suggested atomic detected. This element - helium - was not weights that foretoldneon, krypton, and seen on earth untilalmost thirty years later. familiar D-line of sodium. The English a vacuumtube, and arrangedso that I could astronomerLockyer (Fig. 71) proposed thata see its spectrumand thatof argonin the same new elementhad been detected, which he spectroscopeat the sametime. Thereis argon named helium. So far away, there seemed no in the gas, but therewas a magnificentyellow way to confirma hypotheticalelement on the line, brilliantlybright, not coincident with, but sun, and many spectroscopistsscorned the very close to, the sodiumyellow Iine. 1 was idea. However, JohnW. Draper, first presi- puzzled, but began tosmeIl a rat. " dent of the American ChemicalSociety, was Preferring the superior instrumentationof more visionary:"Helium. . . seems trembling Lockyerand Crookes, he sent thegas to them with excitementto tell its story. . . . And if for spectroscopicanalysis. Sir WilliamCrooks this be the case with the sun,what shall we say (Fig. 72) soon telegraphed backthe electric of the magnificenthosts of the stars? Maynot news: the spectrum was identicalto that of the every oneof themhave specialelements of its "helium"of the sun! own?" The search was on for respectable quantitiesof helium. Italywas considereda likely spot, especially in the gaseous emanationsof volcanoes. Scientistsplodded throughthe mountainsof Italy, on horseback, on mule, and on foot - but helium was discovered only in minute quantities."It is among the rarest of elements," declared Winkler. A few years later huge quantitiesof helium were found in gas wells in the Southwest United States.The first sourcewas in Dexter, Kansas, in 1903, and was discoveredin a comicalway - a dedication Figure 72. Sir WilliamCrooks, whoshared ceremony was planned where gas from the with Bunsen, Kirchhoff,and de Boisbaudran first well in this communitywould be lit, but the honor of establishingthe science of the tapped portion would not support specmscopicanalysis. In his research combustion andextinguished all flames. A Crooksidentified helium, Utalliwn,and other elements. The Crookes'tube, which led to sample sentto the Universityof Kansas proved the discovery of cathoderays, was his the presenceof helium. Becauseof the rich invention. sourceof helium inthe United States, it has Rarnsay in 1895 heated a sample of been extensivelyused for filling balloonsand cleveite(a rare earth-uraniumore, named for dirigibles.Europe, beingmuch poorer in the Per TheodorCleve) and obtaineda gas whose gas, had to make painfbl decisionsregarding spectral linessuggested a mixtureof nitrogen, theinflation of dirigibles- leadingto the use argon, and somethingelse. Ramsay was of hydrogenand the subsequentfiery tragedy thinkingthe spectrummight be "krypton"- of the Hindenburgduring an attemptedlanding a hypothetical heavier analogueof argon. He at LakehurstNJ, in 1937 (for an explanation wrote abouthis puzzlement ina letter to his of the causeof this tragedy,see page 86). wife, Lady Rarnsay:"I bottled the new gas in With two inert gaseson record,the chase was on for hrther members of this family. developed. Only one more inertgas was to be Rarnsay continuedhis search, now with his discovered, radon (see Chapter 13). assistant Morris Travers.They first tried to find new gases by heating rare minerals. Soon they conceded defeat, and returned to the atmosphere. Helium In 1898, boiling away liquid air, they savedthe residues whose spectrumexhibited a He 2 4.00260 new green linesthat did not coincidewith any [Gr. helios, sun] of argon, helium, mercury, or hydrogen. They Discovered spectroscopicallyin the sun determinedthe density and realized the gas fit 1868, collected terrestrially 1895 between bromine and rubidiumof the Periodic < 172.2"; hp-268.9"; Table. In their excitementthey worked late densi& 0.178 g/L into the night and almost forgot Travers' Helium was discovered in 1868 by the examinationfor his doctoratewhich had been French astronomerPierre-Jules-CCsar Janssen. scheduled for the next day! They called the During an eclipse of the sun in India he new gas krypton ("hidden"). observed an unfamiliar yellow line in the Ramsay and Travers realized there was spectrum of the sun's chromosphere. Sir room in the Periodic Table fora lighter gas, Norman Lockyer confirmed the Iine did not and they searched in the more volatiIe belong to any known element; he named it component. When the scientific pair boiled off helium. Most spectroscopists doubted the liquefiedargon, the first fraction was collected existenceof Lockyer's helium and some even and gave a brilliant red spectrum. Its new ridiculed it. In 1895 Sir William Ramsay spectrumimmediately convinced them it must collected some gas from cleveite, whichhe be a new gas. Travers laterexclaimed, "The sent to Lockyer. Lockyer excitedly and blaze of crimson light fromthe tube told its promptly confirmed thatthe new gas gave an own story, and it was a sight to dwell upon identical yellow line. Soon helium was and never to forget. It was worth the struggle discovered in the atmosphere in minute of the previous two years.. . ." This new amounts, and in 1903 helium was discovered blaze of crimson" was neon ("new," named in a gas well in Kansas. Since then huge by Sir William's son), now familiar at night in reserves have been discovered in wells in any city. Texas, Oklahoma,and Kansas. After obtaininga new liquid-air machine, Helium is the second most abundant Ramsay and Traversprepared larger quantities element in the universe, although scarce on of neon and krypton. By repeated fractionation earth. Theboiling pointof helium is cIose to of krypton, a yet heaviergas was sequestered absolute zero. Helium is the onIy liquid that whichgave a beautifblblue glow. They named cannot be solidified by simply lowering the this gas xenon ("stranger"). Soon the vacuum temperature; the pressure must also be tube industrywould use large quantitiesof this increased. Helium is used for filling balloons, gas, giving the faint blue glow familiar to since it is much safer than hydrogen. Helium those working with vacuumtube electronics. is used in breathing mixtures for divers, Hence, in the space of half a decade, a because it has a low solubility in theblood. completenew family of the Periodic Table was Liquid heliumis used in cryogenic research. chairman of the British Association, where Neon they delivered their paper, suggestedthe name Ne 10 20.180 argon, the lazy one. Interestingly,Cavendish [Gr. neos, new] a century before had noticed an inert portion Discovered 1898 of the atmosphere, which undoubtedlywas a -248.7"; hp-246.0"; argon. With the discovery of argon, the hunt &nsity 0.900 g/L was on for further "lazy gases." With the recent discoveriesof helium and Argon is the third most common gasin argon, Sir William Ramsay and Morris W. the atmosphere, constitutingabut 1%. It is Traversbecame fascinated with the possibility prepared commercially in bulk quantities by of discovering furtherinert gases. In a series fractionationof liquid air. It is used in electric of rapid, simple,but elegant experiments, they light bulbs and in fluorescent tubes,and asan isolated in 1898 three additional inert gases inert gas in welding and cutting and other from the atmosphere. The lightest was metallic processes.In chemical researchit is coIlected in the first fractiondistilling off a used as an inert atmospherein situationswhere sample of solid argon. Spectroscopically,the the cheaper nitrogen would react, such as in gas exhibited many, brilliant lines in the red. arc welding and cutting; the production of They named the gas neon. titanium, magnesium, and other reactive Neon is prepared by the liquefactionof metals; and growing silicon and germanium air. It is used in the common advertising signs, crystals. glowing reddish orange. Of all the inert gases, the electrical discharge ofneon is the most intense. Krypton Kr 36 83.80 [Gr. kryptos, hidden] Argon Discovered 1898 Ar 18 39.948 -156.6"; hp-152.3"; [Gr. argos, lazy] density 3.73 g/L Discovered 1894 Iiamsayand Travers evaporateda sample -189.2"; -185.7" of liquid air and collected the residual gas. density 1.78 g/L They observed a brilliant green line in the John William Strutt (the Third Lord spectrum never before observed. They Raleigh) and William Ramsay passed nitrogen determined the densityand concluded thegas over red-hot magnesium and found it would belonged betweenbromine and rubidium in the not be completely absorbed. They suspected a Periodic Table. They named the gas kryptori. modificationof nitrogen (perhaps analogousto Krypton exists in the atmosphereto the ozone, O,, for oxygen), but examining the extent about 1 ppm. Its use is limitedbecause spectrum, they observed new red and green of its high cost - but it is ideal in high bands. They concluded they had a new gas - intensity lamps, such as airport approach the first inert gas - and that there must be an landing systems, because of the white color of entirely new family in the Periodic Table. The the brilliant light. would use the method to discover indium; and Xenon Crookes to detect thallium. This method in the Xe 54 131.29 right hands could be used to analyze mixtures [Gr. xenon,stranger] confirsing mixtures - Demarpy, the discoverer of europium, would become famous in Paris Discovered1898 with his laboratory on Berthoud Boulevard -111.9'; & -107.1"; "LC?, et I&seulement, unspectre compliquS se density5.89 g/L lisait comme une partition d'opira. " ("There, By repeated fractionationof krypton, and there only, could a complex spectrum be Ramsay and Travers separated a still heavier read like the score of an opera.'? Later gas which they named xenon. Spectroscop- Demurcay would help the Curies with their ically, it exhibited a beautifulblue glow. discovery of minute quantities of radium. Xenon exists in the atmosphere to the Nine years aper the invention of the extent of about 0.05 ppm. The gas is used in specroscope by Bunsen and Kirchhog helium electron tubes,stroboscopic lamps, and lasers. was dscovered in the sun. Originally conjlrsed Although a member of the "inert gases," with sodium, the yellow line of helium was xenon forms some exotic compounds with noticeably d~flerent not only because its reactive elements,such as XeF,. position was no1 the same, but also because sdium 'syellow line was actually a double line separated by 0.6 nanometer. Scientists who Radon doubted the proof of a new element gave (SeeChapter 13, page 95) suggested explanations that the line was actually due to a weak line in hydogen that was apparent in a huge reservoir of hydrogen such as the sun;or that the spectra of elements might appear dtxerently in the extreme temper- Recent research has suggested that the ature, pressure, or magnetic conditions of the Hindenburg dirigible caught jire not because stm. the hydrogen was sparked by lightning but Across from a statue of Bunsen in the because a flammable varnish with powdered Altstadt (Old Tmn) of Heidelberg, Germany, aluminum was ignited by static discharge. on a plaque mounted on an old building, readr: Recent engineering advances suggest that hydrogen may be handled and stored safely, "In diesem Hause hat KirchhofS and may become a very economicaljtel in the 1859 seine mit Bunsen begriindete firture. Spectralanalyse atif Sonne und By the time of Ramsajy spectral analysis Gestirne gewandt und damit die had come a long way. Bunsen and Kirchhofl Chemie des Weltalls erschlossen. " had developed the method of spectroscopy lo discover cesium and rubidium. Later, Bois- ("In this building in I859 Kirchoff bau&an studied the rare earths and discovered applied his spectral analysis, that two of them and had con$rmed several others; he had established with Bunsen, to other investigatorswere using spectral analysis the sun and the stars and thereby routinely and were using it to make various unlocked the chemisfry of the claims with the rare earths. Reich and Richter cosmos. "l 13. RADIOACTIVE ELEMENTS

lthough uranium is more concentrated cannot be reduced with hydrogen or carbon, no in pitchblende (uraninite, UOJ, the one suspected anything other than the element Aelement was actually discovered in form was obtained until Peligot in 1841 treated secondary minerals of uranium, which are uranium chloride with potassium, in the manner more soluble and manageable in chemical developed by Davy. Peligot obtained a black analyses (secondary minerals are formed by powder -- elemental uranium - quite unlike leaching of major minerds by water). In 1789 the original material. Berzelius in his investigations of the rare earths investigated a mineral in 1828 which appeared like gadolinite, but which proved to be a silicate of a new metal. Berzelius named the mineral thorife (ThSiO,) and the element ihoritim.He prepared a sample of the metallic element by heating a mixture of potassium with potassium thorium fluoride, as for uranium. Uranium and thorium were discovered many years before radioactivity was known. Radioactivity was discovered by Antoine-Henri ! 1 Becquerel (Fig. 74), who noticed in 1896 that dd .- uranium saltscould expose photographic plates, Figure 73. MartinKlaproth, the first professor of chemisay at the University of . Berlin, who discovered uraniumand zirconium, and verified telluriumand titanium, andperformed critical analyses on ceria.

Martin IUaproth (Fig.73) discovered uranium in Griinerurartgliimmer("green uranium micai') and Urarrocher("uranium ocher") - present- day forbernite (Cu(UOJ,(PO,),~I 1H@) and gummite (yellow mixed uranium oxides of indefinite composition). He named the element after the new planet which Sir William Herschel had recently discovered. By reacting uranium ore residues with charcoal, KIaproth obtained a black substance which he presumed was the element, but which was actually the oxide Figure 74. Anloine-HenriBecquerel, who discovered radioactivity. (uranous oxide, UOJ. Since uranous oxide even when protected by opaque black paper. A the bismuth through her separations. She faster method was developed for detecting concluded in 1898 that she had a new element radioactivity - the electroscope, a device and named it polonium in honor of her native where two hanging gold leafs repel each other country. With an atomic weight of 210, this when in contact with an ionizing source. This element was clearly in the nitrogen family, method of identifjring radioactivity was used by directly below tellurium in the Periodic Table. the Curies and others in their famous inves- Mendeleev himself had predicted "dvi-teUurium" tigations. in 1891 with anatomic weight of 212. The persons most responsible for under- In the processing of their pitchblende ores, standing the phenomenon of radioactivity were the barium salt separation was radioactive as Pierre and Marie Sklodowska Curie. Marie (Fig. well. Subjecting the barium salts to spectro- 75) continued the work begun by Becquerel, scopic analysis (by Demargay), new lines were and found by 1898 that uranium and thorium detected. After laborious fractionationsof the barium chloride, the least soluble part proved to be the most radioactive and exhibited the strongest of these new spectroscopic lines. As the scientific pair finally isolated the white radium chloride salt, they were thunderstruck to observe that it glowed in the dark! At night their laboratory exhibited a soft incandescence, with bottles, capsules, and tubes glowing like "fairy lights" (Fig. 76). The new element, discovered in 1898, they named radium.Marie Curie and Andrk Debierne, a close fkiend, isolated a sample of the shining white metal in 1910. The radioactive decay of uranium and thorium gives a sequence of many elements of varying weights, and it soon became clear that different isotopes of the same element could Figure 75.MarieSklodowska Curie, who have different levels of radioactivity. With each with her husbandPierre discovered new discovery there was cohsion whether a polonium and radium. Mme Curie was the new element had been discovered, or merely a firstperson to receive the Nobel Prizetwice. new isotope of an old element. New names were were the only known elements which were assigned to new discoveries: uranium X,, radioactive. However, she noticed that the uranium X,, brevium (named for its short half pitchblende was more radioactive than uranium Life), ionium, niton, emanium, radium D, E, and itself; andsince the main constituents of the ore F, etc. Sometimes new names were given to oId were known, the responsible radioactive agent discoveries, for example, radium F was actually (presumably in small quantities) must be quite polonium, After several yearssense was made of active indeed. Obtaining several tons of the the tangle, and frequently more than one residues of the Joachimsthal Mine, Czecho- research group has been given credit for the slovakia, she fhctionated the material and found independent discovery of an element, each of that a very radioactive substance traveled with whom arrived at the finding of a particular iso- Figure76. The laboratory of M. andMrne. Curie, where rddiumwas discovered. WiUlelmOstwald described the laboratoryas a "cross betweena horse-stable and a potato-cellar." When M. Curiewas offered theLegion of Homr, he replied, "I prayyou to thankthe Minister, and to inform him hat I do not in the least feel the need of a decoration,but that I do feel the greatest needfor a laboratory."Mrne. Curieconsidered the yearsspent in this ramshackle shed as "the best and happiest" of her life. tope by a different route. pendent discovery of this element are Kasirnir The first element in this series of decay Fajans and 0. H. Gohring in 1913 (named "bre- products was discovered in 1899 by Debierne, vium," or "uranium X,"), and Frederick Soddy, who found it in the rare earth fraction of John A Cranston, and Alexander Fleck in 19 17 pitchblende. This element was named actinirrm. (named by the discoverers, "eka-tantalum"). Next, the Curies had noticed that when air "The stately procession of element comes in contact with radium, it becomes evolution." Soddy showed that when a radioactive. Dorn in 1900 showed this was due radioactive element emits an a-particle (a helium to a radioactive emanation. Rutherford and nucleus) the element shifts two spaces to the left Soddy had observed this same radioactive gas in the Periodic Table (loses an atomic number of emanating fi-om thorium the previous year. 2), whileloss of a 9-particIe (an electron) shifts Rutherford and Soddy then proceeded to prove the element one space to the right (atomic the existence ofthis gas in 1902 by liquefjling it. number increases by 1). The confbsing array of This radioactive gas, named radon, was thus various radioactive elements was caused by this verified as the heaviest gas known when in 19 10 "stately procession of element evolution" as an Ramsay determined the density. atom lost a-particles and P-particles in a specific If pitchblende is treated with hot concen- zigzag sequence to eventually end up as stable trated nitric acid to remove radium and other lead (Pb). The complete sequence of radioactive radioactive components, the insoluble residue evolution was worked out by Soddy and others, remaining contains yet another radioactive sub- including Russell, Fajans, and Fleck. A mineral stance. Hahn and Meitner isolated this material that has lain undisturbed for millions of years is in 19 17 which they called protoactinium (later able to establish a steady-state concentration of shortened to protactinium). Credited with inde- at1 of these elements and isotopes, and this Fiye77. Radioactivedecay series originating from uranium-238.Half-lives are shown for each isotope. The naturalabundance of uranium-238in the earth's crustis 99.27%.

90 1 -a -B

x yr I-). pqf .003 day 3.28 x yr pq7.04 10' 10'

Figure 78. ~adioaitivedecay series originating from uranium-235.Half-lives are shown for each isotope. The naturalabundance of uranium-235in the earth'scrust is 0.72%. A minorroute, not shown above, is the decompositionof Ac-227 to the extent of 1.38%lo francium-223(the 98.62%remainder proceeding as shownabove), whichtransmutes to radium-223 witha half-lifeof 21.8 minutes. Figure 79. Radioactivedecay series originating from thorium-232. Half-livesare shownfor each isotope. The natural abundanceof thorium-232in the earth'scrust is 100%.A minorroute is the decompositionof bismuth212, to the extentof 64.07%to polonium-212,which with a half-lifeof 0.298 psec does not accumulateto anyextent. Po-212 immediately lransmutesto Pb-208. explains why the pitchblende that the Curies passing through paper opaque to ordinary light." investigated contained these trace radioactive Peligot obtained the metal in 1841 byreacting elements. The known sequences for the uranium tetrachloride with potassium. common radioactive elements - U-238 Uranium is extremely important as a (99.27%), U-235 (0.72%), and Th-232 (loo%), nuclear he1 - one pound has the fie1 equi- are given on pages 90-92 (Figs. 77-79). valent of 1500 tons of coal. Nuclear fuels can be Nobe1 prize. In 1903 Pierre and Marie used to generate electrical power, make new Curie, and Becquerel, were awarded the Nobel isotopes, or produce explosives. The main Prize in Chemistry. Tragedy struck three years isotope is U-238 (99.28%, with a half-life of 4.5 later when Pierre Curie was killed while struck x lo9 years), which is used to calculate the age by a heavy vehicle in Paris. After struggling of rocks. The uncommon isotope is U-235 through her grief, Marie Curie accepted a (0.71%, with a half-life of 7.1 x 10' years), professorship at the University of Paris, and which is fissionable with slow neutrons and can with Andre Debierne as an assistant, she sustain a chain-reaction in a reactor containing directed the research in radioactivity. In 191 1 a moderator such as heavy water. Depleted she was awarded the Nobel Prize in Physics - uranium, with the U-235 content lowered to and thus was the first person to receive the 0.2%, is used in inertial guidance devices, ballast Nobel Prize twice. for missiles, and as shielding material. Uranium compounds are typically yeIlow and are used in glazes and glass. The well-known Fiestaware is pigmented red byoxidized uranium. Uranium U 92 238.0289 Thorium planet Uranus] Discovered 1789, metal isolated 184 1 [nor, Scandinavian god of war] g~ 1132.3"; Izg3818"; 18.9 The use of uranium oxide can be dated Discovered 1828 1750"; $B 3800"; spgf 11.72 back to 79 A.D. it was incorporated in a - Berzelius investigated a mineral in 1828 glass mosaic mural in the Imperial Roman Villa on Cape Posilipo, Bay of Naples. Martin H. sent to himfiom Langesund Fjord, Norway and found it to be a silicate of a new metal. He Klaproth in 1789 was the first to recognize uranium as a new element; he isolated black called the mineral thorite and the element UO, fiom secondary uranium minerals (present- thorium. He isolated a specimen of the metal by reacting potassium thorium fluoride with day torbernite, Cu(UO&(POJ,* 1lH20), and gtrmmile (mixed uranium oxides). Klaproth metallic potassium. The radioactivity of thorium was announced by G. C. Schmidt and Marie named the new element siranium, fiom the Curie in 1898. planet discovered by Herschel eight years earlier. Uranium figured prominently in the Thorium is more abundant than uranium there is probably more energy available fiom discovery of radioactivity Henri Becquerel in - - uranium 1896 observed that a sample of potassium thorium than htn both and fossil fbels. However, thorium reactors are not expected to uranyl sulfate exposed a photograph plate become commercially significant for several wrapped in blackpaper! He concluded that the 3300•‹, salt "must emit radiations which are capabIe of years. Thorium oxide melts at the highest of the elemental oxides. The main 0.0001 milliliter of radon gas per day. The haff- present use of thorium (along with a minor life of Ra-226, resulting in a decay sequence amount of cerium) is the manufacture of the &om U-238, is 1600 years. The general problem Welsbach mantle (the trademark for gas of radium poisoning was dramatized by a mantles) using the oxides impregnated in a number of women, who during the World War gauze in a portable lamp. Thorium oxide is used I had made luminous dials. They were wetting as a catalyst in the oxidation of ammonia to the tips of their brushes with their lips - and nitric acid, in cracking petroleum, and the accumulated an excess of radium in their bodies; manufacture of sulfUric acid. Naturally- 24 died of sarcoma or anemia. occurring thorium, with a half life of 1.4 x 10" years, disintegrates producing radon-220. Polonium Po 84 (209) Radium [Polanal Ra 88 226.0254 Discovered 1898, metal isolated 1902 [L. raditis, ray] 254"; Szp962"; 9.3 Discovered 1898, metal isolated 191 1 Marie Curie discovered this element in 700"; 1140"; -5 1898 while she was searching for the cause of In studies of barium chloride, Pierre and unexpected radioactivity in pitchblende - the Marie Curie noticed that one fiaction was level of activity was greater than that expected particularly radioactive, and concluded a new fiom the uranium content. Dr. WilIy Marckwdd element was present (1898). Over a period of of Berlin precipitated a deposit of the metal four several years, the unknown was concentrated years later. through repeated concentrations. Eventually, an Polonium results fkom the radioactive observable amount of chloride salt of the decay of uranium and thorium. Polonium-210 element was obtained - which was so has a half-life of 138.4 days. Gram quantities radioactive that it glowed in the dark! The can be prepared, but the material is extremely Curies named the new element radium.Pierre radioactive - half a gram of metal spontan- Curie was killed in a street accident in 1906 and eously heats up to 500•‹! A milligram of Marie continued the research alone. By 1910 polonium emits as many a-particles as 5 grams she had prepared a gramof radium chloride, and of radium. A ton of uranium ore contains about the next year isolated the metal by electrolysis of 100 pg of polonium. Polonium-210 is used the chloride salt. For her elegant investigations commercially as an a-particle source, and on in radioactive substances, Marie Curie won two static brushes for removing dust fiom photo- NobeI Prizes (one shared in Physics with her graphic films. husband and Becquerel, the other Prize alone in Chemistry). Radium is used in self-luminous paints, Other radioactive neutron sources, and medical applicatio& The curie (Ci) is defined as that amount of elements in nature radioa&vi& having the same disintegration rate In any uranium or thorium ore, in addition as 1 gram ~fRa'~-3.17 x lo1*disintegrations to radium and polonium, there exist several per second. One gram of radium produces about other elements that are produced by radioactive sequences that culminate in inert lead. Since day. Rn-222, the longest-lived isotope, has a these elements are short-lived, they exist in trace half-life of 3.82 days. As for xenon, radon can quantities only in nature. They are virtually form a limited number of compounds with impossible (and illegal!) to acquire in any electronegative elements, e.g., radon fluoride. observable quantities. Some of these elements Radon is used in hospitals for application to were actually first discovered by their artificially patients. Radon collects in basements and can creation, and therefore technically speaking constitute a health hazard. should belong in chapter 15, but all are included here because they do occur in nature.

Fr 87 (223) Astatine [France, site of Curie Institute] At 85 (210) Discovered 193 9 [Gr. mtaios, unstable] 27";hp 677" Discovered 1940 In 1939 Mlle. Marguerite Perey of the a 302"; & 337" Curie Institute of Paris discovered francium as Corson, Mackenzie, and Segrh synthesized an &-decay product of actinium. The longest- this element in 1940 by bombarding bismuth lived isotope has a half-life of 22 minutes (see with alpha particles. Since the naturally caption to Fig. 78, page 91). The total amount occurring isotopes of astatine all have half-lives of fiancium in the earth'scrust is estimated at less than a minute, only minute traces exist in less than an ounce. nature - the total amount of astatine in the earth's crust is estimated at less than one ounce. Actinium Ac 89 227.0278 Radon [Gr. akiinos, beam or ray] Rn 86 (222) Discovered 1899 [fiom radium] 1050"; 3200"; so.ar.10.07 Discovered 1900 This element was discovered by Debieme -71 "; $p -61 .go;density 0.00973 g/L in 1899; then by Giesel in 1902. Actinium-227 Dorn observed radium emanation in 1900, is a decay product of U-235, with a half-life of but did not understand its nature. Rutherford 2 1.6 years. It is 150 times as active as radium. and Soddy characterized the gas, were able to LiqueQ it, and were the first to recognize the gas as an element and as a decay product of radium. Protactinium They aIso had previously discovered the gas as Pa 91 231.0359 an emanation product of thorium. Ramsay in [Gr. protos, first (member 1908 measured its density and determined it as of the actinium series)] the heaviest gas known. Discovered 19 18 Radon is a radioactive, chemicdlyinert pp 93 1"; 3520"; SD.gr. 6.77 gas, which is produced naturally fiom radium Hahn and Meitner isolated samples of this (Ra-222) and thorium (Ra-220). One gram of element from pitchblende after the other radium produces 0.0001 rnL of radon gas per radioactive materials and tantalum(which chem- After Klaproth characterized uranium, ically resembles protactinium) were separated. miners called pitchblende "Pechuran, " or Credited with independent discovery of this "bad-luck uranium," because it did not element are Kasimir Fajans and 0. N. Gohring contain any of their precious silver. Klaproth in 1913 ("brevium," or "uranium X;'), and performed subsequent work on pitchblende, Frederick Soddy, John A. Cranston, and which had previous been considered to be an Alexander Fleck in 191 7 ("eka-tantalum"). In ore of zinc and iron. He dissolved pitchblende 1927 two milli-grams of protactinium oxide in nitric acid and observed a yellow precipitate (Pa@5)were prepared by A. V. Grosse, and he when he added potnsh. This yellow solid was reduced the metal element f?om the oxide in uranium oxide with an oxidation stare greater 1934. Protactinium-234 is a decay product in than +4. He reacted this yellow solid with the U-238 series, with a half-life of 6.7 hours; charcoal to produce black UO,, where the At-23 1 is a decay product in the U-235 series, oxidation state of uranium is +4. Klaproth with a haIf-life of 32,700 years. therefore had a pure form of uranous oxide, UO,. 17tis was erroneously considered to be the element, because it could not be easily Radioactive elements reduced. The metallic element itself was not in an ore sample produced rintil half a century later when Eug2ne Peligot of Paris reacted uranium tetra- In a rich sample of pitchblende (such as chloride with potassium. the one on display at UNT), the following A mberof beaunil secondary uranium elements are calculated to be present in the minerals exist, which vary from canary yellow following approximate amounts: to malachite green. Examples are: Uranium-238 ...... -10 grams Torbernite (Cu(UOJ,cipUj),~I~H,O), Uranium-235 .... -70 milligrams(7 x 1W2gram) green mica-like flaky crystah (the compotind Uranium-234 .....-0.5 milligram(5 x lo4 gram) originally studied by Klaproth); Polonium-2 10 ..... -1 nanogram(1 x I Wggram) A ulunite (Ca(UOJ2(POJ2*10-I 2H20), Radium-226...... -3 micrograms (3 x lo6 gram) yellowish-green crystalline scales whichfluor- Actinium227 ..... -2 nanograms(2 x 1W9gram) Protactinium-23I .. -3 micrograms (3 x 10a gram) esce brilliant green; Radon-222 ...... -2 x 10-" gram Su&iyite (U03Ji04.H,0), amber-yellow Astatine-218and -219 .... - gram (- I atom) resinous crystals, named for Frederick Sodby; Francium223 ...... - gram (- 1 atom) Curite (Pb,U,0,,~4H20), orange-red or vermillion prisms, named for Pierre Curie; Sklodowskite, lemon-yellow fibrous nee- Although most discoveries of radioactive dles (ugf130)2(vOJiOJ2*4H20),named for elements have been per$omed through the Marie Sklowdowska Curie. A great deal of the internal heat gener- analysis of pitchblende (uraninite, UOJ,the ated in the earth is due to Ihorium and uranium first discoveries by Klaproth were made on through radioactive decay. Before this source secondary uranium minerals, which he found of heat was known, the age of the earth was must easier to dissolve for analysis. These reckoned to be much younger than its actual secondary minerals (commonly +6 oxidation 4.6 x lflyears,since obvious& "it had not had state) result from long-tern oxidation and much time to cool of since its origin. '' weathering of uraninite (+4 oxidation state). 14. MOSELEY AND ATOMIC NUMBERS

endeleev's insight that the Periodic that the Periodic Table appeared to suggest? Table should be based on chemistry Henry Moseleygave a definite "yes" to this rather than atomic weight was query - the Periodic Table should be based on accurate prophesy - tellurium has a higher an "atomic number," avariable thatcould be atomicweight than iodine; argon has a higher defined on the basis of X-rays of the elements. atomic weight than potassium; cobalt and Moseley (Fig. 80), a lecturer and then nickel, and thorium and protactinium have researcherat the Universityof Manchesterand similar discrepancies; and the radioactive later at Oxford University, was fascinated with elements have very confbsing and variable Max von Laue's recent discovery thatthe lattice of atoms in a crystal would diffract X- rays. In this method, X-rays are generatedby bombarding a metal with cathode rays (electrons),and various metals emit X-rays of different frequencies. Curious as to what the relationshipwas between an element and the frequency of the X-rays radiated, Moseley conducted a thorough investigationof dl known elements(Fig. 81), and he plotted the X-ray frequenciesagainst the atomic number. A simple and yet elegant relationshipemerged:

Figure 80. Henry Moseley, who discovered the relationship between the atomicnumber of an element and the frequencyof itsX-ray spectrum.On the basis of his work a uuly numericalPeriodic Tablecould be constructed. He was killed in World WarI at the age of 27. zic weights. But then the question rema is there a numerical basis of the Periodic Table Figure 81. Moseley's X-raydata. The K, at all? Is there indeed any meaning to the line shifts posilionin a mannerthat predicts "ordinal number" or "number of the element" the atomic numberof the elements. of a givenelement, thesquare root of the X- efil method of Moseley immediately fore- ray frequencyis directlyproportional to the told exactly how manyelements should exist, atomic number: and thus howmany were left to be discovered. Professor Urbain,who had worked twenty years on the rare earths, visited Moseleyand in only a fm days confirmedhis valuesfor the atomic numbersfor erbium, thulium,ytter- I bium, and lutetium! where Now a systematic PeriodicTable should N = the atomicnumber ofthe element; truly be devised (Fig. 82). It was now obvious v = Ilh = the observedwavenumber of that sevenmissing elements would be found in the X-ray line (theK, line); precisely numbered positions (through v, =a constant (the Rydberg constant). uranium,or atomic number92). Furthermore, Moseleyhad borrowed this constantfrom the althoughit was not clearjust what was going work of J. Rydberg, who had foundin 1890 on in the rare earths, neverthelessit was clear that the wavenumberv = I/A could be related that elements61 and 72 were to be discovered. to the emissionspectra ofthe hydrogenatom Urbain had searcheddiligently with Moseley in the Balmerseries, givingrise to the constant for these two elements inhis rare earth that bears his name.This new, extremelypow- mixtures,but foundno trace.

PERIODIC TABLE OF THE ELEMENTS 11 9 1 2 - after Moseiev)

Figure 82. Moseley'sX-ray methods allowed absoluteatomic numbers to be used; now it was known with certainty how many elements werenot yet discovered those with atomicnumbers 43,61,72, 75.85, 87, and91. Hafnium. On the basis of Moseley's in specific orbits. He arrived at a scheme for work there clearly existed an element below this internal structure of the atom that zirconium. Urbain had previously believed that corresponded with the Periodic Table. Thus, he had seen evidence for this element 72 in an he assigned inner electrons (d-electrons) to the arc spectrum of a rare earth mixture, and he transition elements and another group of had even given a name to the element hoped deeper electrons (f-electrons) to the rare for - celtium. However, a visit to Moseley earths. Bohr understood that during the and his apparatus in Oxford resuIted in no building up of these deeper electron orbitals, a indication that there was any element 72 separate class should exist similar to whatsoever. After World War I, Urbain lanthanum (element 57), but that after the continued to search in the rare earth residues completion of deeper electron layers the but could never find anything encouraging. elements should continue in the normal The reason for his failure was that he was manner. Previously, scientists had assumed 72 looking in the wrong place, as became clear would behave like 71 (lutetium), but Bohr said from Niels Bohr's work. no, element 72 should behave not like the rare Bohr (Fig. 83) had been elucidating the earths but like zirconium. meaning of the Periodic Table in terms of Taking the hint of Bohr, Dirk Coster and atomic structure. He was able to explain the George de Hevesy made a thorough search in anomalous behavior of the rare earths and why Norwegian zircon and other minerals and they lay in a group all by themselves. Bohr, found the new element in 1923. To their adopting Planck's quantum theory, developed surprise, this new element hafnium behaved a structurefor the atom where theelectrons lay almost identically to zirconium, and thus could be separated only with difficulty. In fact, previous "pure" zirconium samples were found to contain substantial amounts of hafnium (sometimes as much as 5%!). Subsequent study showed that because of the lanthanide contraction, hafnium and zirconium had almost identical atomic volumes, thus explaining the similar behavior. Modern methods are capable of ferreting out minor amounts of hafnium. In Figure 84 (page loo),energy dispersive X-ray spectra (EDX)are presented for samples of zircon. EDX spectra can be obtained fairly quickly and are used extensively by mineralogists by determine the chemical composition of speci- Figure 83. Niels Bohr, who adopted mens. With proper equipment the composition Planck's quantum theory to Rutherford's of minute samples (a micrometer or less in model for atomicstructure; therebyhe diameter) can be ascertained, which has been definedthe structure of the atom and how used a great ded with platinum group thisstructure gave rise to the Periodic Table of the elements. compounds (see page 55). Some zircons, parti- cuIarly the gem-like specimens, can contain relatively pure zirconium. Other forms of zircon (see Figure84) can contain substantial amounts of hafnium. The extreme composition of 100% hafnium, called "hafnon" with an ideal formula of HfSiO,, has never been seen in nature, but reputedly has been closely approachedin rare cases(99%). Rhenium. At the beginning of the twentieth century manganese had no other members in its periodic column. Thinking that element 75 might have similar propertiesof manganese, Noddack, Tacke, and Berg carried out a 100,000-foldconcentration in gadolinite, and by a carehl inspectionof the X-ray lines found the new element in 1925, which they named rheniumfrom the German Rhine River. By processing 660 kilogramsof molybdenite, a gram of rhenium was prepared in 1928. By the X-ray technique this scientific group also thought they had discovered element 43, directly above rhenium in the Periodic Table. They dubbed this element "masuriurn." This claim has not been verified (see page 103). LcScientit?callyprecise Periodic Table." By 1925 the Periodic Table appeared as shown in Figure 85 (page 101). Now it was known that (through uranium) only four elements

Figure 84. Energy dispersive X-ray spectraof zircon (nominally ZrSi0,) samples. In normal energy dispersive X-ray, only elements aboveatomic number 10 can be observed; hence, oxygen is not seen in these specm. This method is customarily used in conjunction with scanning electron microscopy. Sample (a) is a gemmy,nicely crystalline specimen from Malawi that analyzes only for zirconium and silicon, and therefore is a pure sample of ZrSiO,. Sample @) is a radioactive variety called "alvite"fmm Norway, that analyzes for 15% hafnium, and is the same materialoriginally studied by Hevesy in his discovery of hafnium. Other impuritiesinclude uranium,calcium, manganese, and iron. Sample (c) is a sample of cyrtolite, hwn Ontario, Canada, another variety that has a messy composition that includes a smaller concentrationof hafnium,but larger concentrationsof aluminum,iron, nickel, and copper. Mineralspecimens generally commonly contain impurities that baffled theearly mineralogists,who had access only to ambiguous chemical analysis with multiple interferences. It is impressive that these early scientists unraveled the compositions of complex minerals using only these toilsome, complexchemicaI schemes. PERIODIC TABLE OF THE ELEMENTS

Figure85. Periodic table of the elements, 1925, after Moseley haddefined atomic numberin terms of his X- raydata, andBohr hadexplaid (he behavior of tratlsition elements and rare-earth elements in 1922. Hafnium was discoveredin zirconiumore after Bohr's suggestionthat the missing element would behave more like zirconiumthan likea rare earth element. Rheniumwas discovered fromplatinum ores. "Masmiurn"(eka- manganese,43) and "illinium"(the missing rare earth. 61) were announcedbut later discredited. remainedto be discovered. These elements had to await artificial synthetic techniques (see Hafnium next chapter), Hf 72 178.49 The elements 90-92 (thorium, protac- [L. Hafinia,Copenhagen] tinium, uranium) were pIaced in the groups of Discovered 1923, metal isolated 1925 titanium, vanadium, and chromium - but it 2227"; & 4602"; 13.31 became clear later (see next chapter) that 90- In 1914 Henry Moseley suggested that, 92 should lie in a row analogous to the rare within the limits of his X-ray technique, earths, directlybelow the lanthanides. (elements 13-79, aluminum-gold), he could When Great Britain entered World War predict the lines for the missing elements (43, I, Moseley promptly and patriotically entered 61, 72,75). Niels Bohr suggested that element the military service, He was killed while 72 would have properties similar to those of engaged on the Turkish front, at the age of 27. zirconium. Dirk Coster and George de Hevesy No brilliant scientist has undergone a more thus investigated zirconium minerals, and were premature, tragic end. Because of Moseley's amazedto find substantial amountsof element insight, as Urbain stated, Mendeleev's rom- 72 in all zirconium preparations (1-5%), even antic classification had been substituted by a those which had previously been thought to be "scientifically precise Periodic Table. " pure. They named the element hafnium for Copenhagen, the city in which the research was conducted. Hafniumhad been overlooked filaments in ion gauges. Rhenium withstands not because of its rarity, but because of its arc corrosion and is used for electrical remarkable similarity to zirconium - the contacts. Thermocouplesof Re-W can measure separation of zirconium and hafnium is even temperatures to 220O0,and rhenium wire is more difficult than that of niobium and used in photoflash lamps. tantalum. George de Hevesy and Thal Jantzen separated hafniumfrom zirconiumby repeated recrystallization of the ammonium or potas- The reasonfor the remarkablesimilarity sium fluorides. The metal wasprepared by A. between zirconium and hafitium is the E. van Arkel and J. H. de Boer in 1925 by "Ianthanidecontraction" - thefilling of the 4f passing the tetraiodideover a heated tungsten orbitals through the lanthanide elements filament. between lanthanum (57) and hafitium (72). Hahiurn is almost chemicallyidentical to Through this series, there is a steady increase zirconium; however,hafnium has twice the of the gective nuclear charge, producing a density. Generally foundin zirconium min- decrease in size. Thus,the third transition erals, thesetwo metals are extremelydifficult elements are remarkably similar to the to separate. Hafnium has a good absorption respectivesecond series elements,particularly cross section for thermal neutrons(600 times at the beginning of the series, where atomic that of zirconium) and is used in reactor sizes are almost identical: zirconium and control rods, commonly in submarines. hajhium. Similarly, in the next family, niobium Hafnium carbide and nitrides are excelIent ondtantalum were confused for many years - refractories. Wollastoneven thought the two elements were identical (seepage 19). The power of Bohr *s insight was borne out when virtually overnight it becameclear Rhenium that the search for element 72 in rare earth compounds was in vain. Upon Bohr's recom- [L.Rhenus, Rhine] mendation, Hevesy turned to the Copenhagen Discovered 1925, metal isof ated 1928 Geology Museum for a sample of alvite to m~ 3180'; hp5627"; 21.01 malyze (a type of zirconium, see Figure 84, By a 100,000-fold concentrationin page 100) - and the rest is history. gadolinite, the Germanscientists WaIter Noddack, Ida Tacke, and Otto Berg detected element 75 in Berlin at the Physikalisches- TechnischesReichsanstalt by Moseley's brand- new X-ray techniques. Three years laterthey were able to isolate a gram of the elementby processing 660 kilograms of molybdenite. They named the element rhenium in honor of the German Rhine River. Rhenium has a melting point exceeded only by tungsten and carbon, and is used for 15. THE ARTIFICIAL ELEMENTS

y 1925, despite a tremendous amount nature in any appreciable quantities; they were of searching, four elements escaped very short-lived, radioactive substances. Bdetection - elements 43, 61, 85, and The key to discovering the remaining four 87 - and apparently uranium - 92 - was the eIements was found in the artificial trans- end of the list. A pair of claims had been made mutation of elements. Lord Rutherford, in 1919, to fill in the gaps but were withdrawn. The had shown that nitrogen-14, when bombarded same scientists who discovered rhenium - with highly energetic helium atoms, would Noddack, Tacke, and Berg in 1925 - also transmute into oxygen-1 7: believed they observedX-ray lines for element 43, which they namedmasurium (named for Masuria, a region in East Prussia, now Northeast Poland), but this announcement was In 1930 W. Bothe and H. Becker saw a later discredited. A continuing debate to this very hard radiation produced by bombarding day - on which several articles have been beryllium with helium atoms. Jean-FrCderic written, both pro and con - is whether Joliot and Irkne JoIiot-Curie (the daughter of Noddack, Tacke, and Berg in 1925 with their Pierre and Marie Curie) and Professor James equipment could have detected the X-ray lines Chadwick showed that a neutronwas produced for masurium (technetium) and whether in fact in this reaction: they did observe the element. In 1926 J. A. Harris and B. S. Hopkins concentrated mozanite sands which gave X-ray lines which they claimed were element 61, and they it named it illirtium. Meanwhile, Luigi M. and Mme. JoIiot-Curie discovered Rolla and L. Fernandes claimed they had detect- many kinds of transmutations and found that ed element 61, which they namedflorenlium. some artificially produced elements are radio- Fred Allison claimed he had discovered active, and thus they synthesized isotopes which element 85, which he named alabamine. had not been previously known. For example, Several investigators asserted they had the reaction of boron-10 with helium gave found element 87, which was given the various nitrogen-13, which decayed with a half-life of 14 names nissitim, alcalinizim, virginirim, and minutes: moldavium. But none of these discoveries could be verified. After the eIements had finally been prepared artificially, it was realized that they ';N -B ':C +:e were not found because they could not exist in (2eis a positivelycharged electron, or positron) By 1940, 330 artificial isotopes had been made by Mlle. Marguerite Perey at the Curie described, which included isotopes of every Institute of Paris in 1939. She showed that known element in the range 1-85, as well as actinium-227 decayed to give an element she thorium and uranium. named ~urzcium.Ordinarily actinium-227 This new technique of M. and Mme. decays by P-decay to give thorium-227 (see Joliot-Curie was used by other investigators to Figure 78, page 9 1). However, about I % of the synthesize the four remaining elements: numbers actinium decays by a-emission to give a new 43,61, 85, and 87. element she calledji-ancium: Element 43. A long-standing mystery was element 43. Why should anelement with such a low atomic number be so elusive? In 1936 Segrh analyzed a sample of molybdenum that had been The chemistry showed the properties were that bombarded by deuterons by Ernest Lawrence in of an alkali metal. Chemical separations, which his cyclotron in Berkeley which had been sent to involved precipitations by ammonium bisulfates, his laboratory in Italy. By extracting the treated tartrates, or chrornates, had to be performed molybdenum with ammonium hydroxide-hydro- very rapidly, because the half-life of the longest- gen peroxide, he was able to isolate a radio- lived isotope of fiancium is about 20 minutes! active portion which was approximately 10- '' Element85. Segd, who had moved to the gram of the new element, named technetium: University of California at Berkeley, was involved with Dr. R. Corson and K. R. Mac- kenzie in the discovery of element-85. Bomb- ardment of bismuth with at-particles produced Larger quantities of technetium were this element, named astatine, in 1940. subsequently available by bombardment of molybdenum with neutrons and niobium with helium ions. Technetium was also detected in fission products fiom uranium. All isotopes of The longest-lived isotope is At-2 11, with technetium proved to be radioactive. The a half-life of 7.21 hours. longest-lived isotope, Tc-98, has a half-life of Element61. Attention was next turned to 4,200,000 years. the rnissiig rare earth element. Fission products The instability of technetium permitted fiom an atomic pile containing uranium con- development of theories regarding the structure tained, among other elements, rare earths fiom of the nucleus. It became apparent that the lanthanum through europium. Using the ion- construction of the nucleus has "shells" as do exchange techniques developed by Spedding the electrons of an atom, and various combin- (see Chapter 1l), milligram quantities of the ations of protons and neutrons would allow new element 61 were isolated in 1941 by I. A. predictable stabilities. The number of protons Marinsky and L. E. Glendenin at Oak Ridge was particularly important - aneven number of National Laboratory, in the group of Charles D. protons tended to promote stability; an odd Coryell. All isotopes of this element, named number of protons would not be so favorable. promethium, proved to be radioactive. The Indeed, all four of the remaining elements had longest-Lived isotope, Pm-145, has a half-life of odd atomic numbers. 17.7 years. Element 87. Discovery of element-87 was Source of heaw elements. The vast majority of material in the universe is hydrogen was originally created in 1940 and was and helium. Heavier elements are created in produced in the wartime economy in a race to supernovae. The heavier elements in the earth's ensure the U.S. attained the atomic bomb before crust originated fiom the primordial material Germany. Through the following years Seaborg fiom a supernova captured by the sun and as the and Ghiorso stepped through several elements, planets formed. Hence, during the beginning of and later groups in Russia and Germany have the solar system, significant quantities of continued the climb. Today the list extends transuranium elements undoubtedly existed - beyond 100, with ever-increasing instability. even above 92 - but decayed until only This quest for elements of higher atomic elements 1-92 remained. Hence, all elements number seems more and more elusive - but beyond uranium on earth are artificial. there is a reason to explore the mher regions. Actually, there is evidence that small, but Glenn Seaborg suggested that there should be significant, amounts of neptunium and pluto- an "Isle of Stability," perhaps around atomic nium have been synthesized in natural atomic number 125, and observation of an element of piles in the earth's crust at a much earlier age this size would be of great theoretical interest. (millions of years ago) when the amount of U- Current theory suggests that perhaps an element 235 was greater and could concentrate to with 114 and 184 neutrons would have sur- critical levels. Ever since atomic fission was prising stability (Fig. 88, page 111). discovered, the detonation of atomic and With the increasing atomic number of the hydrogen bombs have created elements beyond elements with their shorter lives - shrinking to uranium in trace quantities in the earth's atmos- milliseconds in some instances - naming a phere and crust. compound seemed to some as contrived, and With the understanding that artificial Glenn Seaborg himself suggested that starting elements could be synthesized, Glenn Seaborg with atomic number 104, the name of the ele- (Fig. 86) at the University of California at ment should simply reflect the atomic number. Berkeley embarked on a journey beyond Element-104 would be "unnilquaddium," uranium: the transuranium elements. Plutonium element-105 would be "unnilquinnium," etc. However, the tendency to derive names for all elements continued, even for elements 104 and above. It is ironic that Seaborg himself has been thus honored (element- 106 = "seaborgium"). Indeed, he is the first person for whom an element has been named during his lifetime. It would be desirable to extend UNT's collection of elements beyond 92. Unfortun- nately, the public exhibition of elements beyond uranium is against National Regulations, and display of transuranium elements are not possible in a university course. Therefore, the descriptive story of the elements comes to an appropriate endwith uranium, element-92. In the following short summaries of each artificial Figure 86. GlennSeaborg, discovererof the transuranium elements. element, a fullportrait is given, as in previous chapters, for those artificial elements embraced the first element to be produced artificially. All through 92. A shorter description is given for isotopes of technetium are radioactive. Techne- the transuranium elements. tium is not generally available for consumer It is to be stressed that particularly for the applications. higher elements, all reports mandate verification and reproducibility. Sometimes only one atom has been observed! Indeed, sometimes certain claims may be retracted. For example, an Promethium announcement in 1999 by the California group Pm 61 (145) that they had observed Elements 116 and 118 [Promethus] has been retracted. Prepared 194 1,metal isolated 1963 1042"; bp3000'; 7.26 In 1941 J. A. Marinsky, L. E. Glendenin, and C. D. Coryell at Oak Ridge National Laboratory obtained a mixture of fission Technetium products of uranium; by using ion-exchange Tc 43 (99) chromatography on Amberlite resin they were able isolate element 61 in milligram quantities. [Gr.techtetos, artificial J This ion-exchange technique had been Prepared 1937, metal isolated 1952 developed for the transuranium elements and 2172"; hg 4877"; 11.50 was the same method utilized for separation of By 1937 alIattempts to discover elements the rare earths (see Chapter t 1). They named 43, 61, 85, and 87 had failed. Number 43 was the element promethium after Prometheus, the particuIarly intriguing, since it was such a low Titan who stole fire from heaven for use on atomic number. Ernest Lawrence sent to Segri earth symbolizing the awesomeness of and C. Perrier at Palenno a sample of molyb- - nuclear power. In 1963 Fritz WeigeI obtained denum which had been bombarded in the cyclo- the metallic element by heating promethium tron for months with a deuterium beam. It was trifluoride with lithium in a tantalum crucible. found (1937) that a new element could be Promethium, never found naturally on extracted in small amounts (estimated at 10"' earth, has been observed in stars. The longest- gram) with ammonium hydroxide-hydrogen lived isotope of promethium is Pm-145, with a peroxide. Soon other methods were developed half-life of only 17.7 years. Research is being to prepare larger amounts of the element. All conducted to explore its use in a nuclear- isotopes were found to be radioactive and powered battery. unstable. At Oak Ridge National Laboratory, the reduction of the technate with hydrogen gave the metal which tarnished slowly in moist Francium and air (1952). Although technetium has not been found on earth, its spectral lines are observed in Astatine older stars (though not in the sun). Astronomers (See Chapter 13, page 95) believe that technetium is formed continuously in the later stages of a star, and that the sun is too young for this to occur. Technetium, not occurring in nature, was might be surprisingly stable - if only one can discover a way to synthesize them. These stable elements would lie in a theoretical "Isle of elements Stability" in a sea of uncharted waters (Fig. 88, The three main players of the Trans- age 111). uranium Game have been the University of California-Berkeley; U.S.A.; GSI (GesellschaR Neptunium Np 93 237.048 6r Schwerionenforschung), Darmstadt (near [Neptune]Discovered 1940 640"; Frankfort), Germany; and the Joint Institute for 3902"; 20.45 Nuclear Research, Dubna (near Moscow), Neptunium was the first artificially Russia. The leaders of the American effort have synthesized transuranium element, prepared in been Glenn Seaborg and Albert Ghiorso. G. N. 1940 by bombarding uranium-239 with Flerov has headed the Russian development. At neutrons, by E. M. McMillm and P.H. Abelson. G.S.I.in Darmstadt, Matthias Schadel has been Np-237 can be prepared in large (gram) particularly successfL1 in conducting chemical quantities as a byproduct of nuclear reactors. reactions including analyticalseparations with Longest-lived isotope: Np-237, with a half-life heavy elements, notably seaborgium (they must of 2.14~10~years. be done rapidly, in a matter of seconds!). Over the past haIf century each of the PhtoniumPu 94 (244) three research groups has adopted a particular approach that appears to be successfid with a [PhtoJDiscovered 1940 64 1" ; 3232" ; particular group of elements. The Berkeley 19.8 approach - to bombard elements with highly Plutonium was prepared in 1940 by energetic light particles to create a new, fused bombarding uranium with deuterons by species - worked for the first few decades. Seaborg, McMillan, Kennedy, and Wahl. However, the resulting particles were so Plutonium is now prepared in kilogram energetic that they tended to fission rather than quantities. Plutonium was used in the atomic relax into a stable state, and the effort stalled bomb at Nagasaki (uranium-235 was used at after a dozen elements or so. The German Hiroshima). Plutonium is a very dangerous approach was to accelerate heavier particles to radiological hazard. Longest-lived isotope: Pu- bombard light targets, resulting in hsed 244, with a half-life of 8.0~10' years. products with lower excitation energies. This process is known as "cold fusion" (not to be AmericiumAm 95 (243) conhsed with the discredited reaction occur- [America] Discovered 1944 ma944"; ring at conventional laboratory temperatures). 2607";spgt: 13.6 The Russian group has adopted the same Americium was produced in 1944 by approach. Seaborg, James, Morgan, and Ghiorso by Here is a listing of the transuranium reacting plutonium with neutrons, and is now elements. Sometimes elements beyond 100 are prepared in large quantities by the natural decay called "transfermiurn." Above lawrencium of plutonium. Americium is used as the (1 03), the last actinide, the elements are called radioactive agent in smoke detectors. Longest- "superheavy." Above 1 10, the elements are of lived isotope: Am-243, with a half-life of 7370 great theoretical interest because some of them years. CuriumCm 96 (247) Mendelevium Md 10 1 (260) [Curie] Discovered 1944 m_n1340"; [Dirnitri Mendeleev] Discovered 1955 SpgI 13.5 Mendelevium was synthesized by Seaborg, Curium was produced in 1944 by Seaborg, Thompson, Ghiorso, and street by bombarding James, and Ghiorso by bombardment of einsteinium with alpha particles. Longest-lived plutonium with helium. Longest-lived isotope: isotope: Md-258, with a half-life of 5 I .5 days. Cm-247, with a half-live of 1.56x107 years. NobeliumNo 102 (259) BerkeliumBk 97 (247) [AlfredNobeCJ Discovered 1958 [Berkeley, site of transuranium discoveries] Nobelium was produced by bombarding Discovered 1949 curium with carbon by Seaborg, Ghiorso, Berkelium was produced in 1949 by Sikkeland, and Walton. Longest-lived isotope: Seaborg, Thompson, and Ghiorso by reacting No-255, with a half-life of 3.1 minutes. americium with alpha particles. Longest-lived isotope: Bk-247, with a half-life of 1400 years. LawrenciumLr 103 (262) [Ernest Lawrence, inventor of the cyclotron] Californium Cf 98 (25 1) Discovered 1961 [California, site of Berkeley laboratories] Lawrencium was produced by Ghiorso, Discovered 1950 Sikkeland, Larsh, and Lather by bombarding Californium was produced by Seaborg, califiornium with boron atoms. Longest-lived Thompson, Ghiorso, and Street by bombarding isotope: Lr-256, with a half-life of 28 seconds. curium with helium. Longest-lived isotope: Cf- 25 1, with a half-Iive of 900 years. RutherfordiumRf 104 (26 1) pmest Ruthegord,discoverer of artificial trans- Einsteinium Es 99 (254) mutation] Piscovered 1969 [Albert Einstein] Discovered 1952 Rutherford was synthesized by Ghiorso Einsteinium was detected in the debris and others by bombarding californium with from the first hydrogen bomb by Ghiorso and carbon. Longest-lived isotope: Rf-257, with a others. Longest-lived isotope: Es-252, with a half-life of 4.7 seconds. half-life of 1.29 years. DubniumDb 105 (262) Fermium Fm 100 (257) [Dtrbna, Russia, site of Joint Institute for [Enrico Femi, discoverer of chain reaction] Nuclear Research] Discovered 1970 Discovered 1952 Dubnium was synthesized by Ghiorso and Fermium was detected in the debris from others by bombarding californium with nitrogen. the first hydrogen bomb by Ghiorso and others. Longest-lived isotope: Db-262, with a half-life Longest-lived isotope: Fm-237, with a half-life of 34 seconds. of 110.5 days. SeaborgiurnSg 106 (263) Element 11 0 110 piscovered 1994 [Glenn Seaborg, discoverer of transuranium This element was synthesized in Germany elements] Discovered 1974 by bombarding bismuth with cobalt. Longest- Seaborgium was the first element named lived isotope ? The half-life of the 269 isotope after a living person. It was produced by was 170 microseconds. bombarding californium with oxygen, independently announced by workers at the Dubna, Element 11 1 11 1 Discovered 1994 U.S.S.R. Institute and by the Lawrence Liver- This element was synthesized in Germany more Laboratories. Longest-lived isotope: Sg- by bombarding bismuth with nickel. Longest- 263, with a half-life of second. 0.8 lived isotope? The half-life of the 272 was 2042 microseconds. Bohrium~h 107 (262) mels Bohr, interpreted atomic structure of the atom] Discovered 1976 Bohrium was produced by bombarding bismuth with chromium in Germany. Longest- lived isotope? Bh-262, with a half-life of 0.1 second, has been observed. In the decay series of Element 11 1, Bh-264 with a half-life of 1.4 seconds was observed.

HassiumHs 108 (265) batin Hassia, Hessen, German state where the GeseUschaft fb Schwerionenforschung, GSI, is located, in Darmstadt] Discovered 1984 Hassium was synthesized by bombarding lead with iron at GSI. Longest-lived isotope? fissionin 1938 (with OttoHahn). "She died Hs-265, with a half-life of 2 milliseconds, has some 30 years beforeshe receivedproper been observed. In the decay series of Element recognitionfor her work." Some believe 112, Hs-269 with a half-life of 9.3 seconds was Hahn withheldlegitimate creditthat would observed. havecertainly earned Meimr the Nobel Prize. Caught up in the maelstrom of World War 11, she fled Gemany in 1938. The Meitneriurn Mt 109 (266) Nobel Prizein Chemistry was awardedto [Lise Meitner, codiscoverer of fission, Fig. 871 Nahnalone in 1944. Discovered 1982 Meitnerium was synthesized by bombarding bismuth with iron at GSI. Longest- Element 11 2 11 2 Discovered 1996 lived isotope? Mt-266 has been observed with a This element was synthesized in Germany half-life of 3.4 milliseconds. In the decay series by bombdig bismuth with zinc. Longest-lived of Element 11 1, Mt-268, with a half-life of 72 isotope? The half-life of the 277 isotope was milliseconds was observed. 240 microseconds. Element 1 14 114 Discovered 1998 The GSI group has been exploring the question: Should the stperheavy elements be This element has been claimed by the placed with the transition (d-block) elements? Russian research group by bombarding plutonium with calcium. Ody one atom was Thalis, should rutherjordium (I04) be located below hafitiunt, dubnium (105) bebw tanfaltrm, detected. The half-fife of the 29 1 isotope was an incredibly long 30.4 seconds, decaying to seaborgium (106) below tungsten, bohrium (107) below rhenium, and hassnium (108) element-1 12, which in turn decayed in 15.4 minutes to element-1 10, which decayed in 1.6 below osmium? The GSI research has shown minutes to element-108. Element-108, far fiom that there are disparities, but that nevertheless the island of stability, fissioned spontaneously. the transactinides may indeed closely resemble Another claim by the Russian group for Element homologs in the respective chemical families. 114 involved the 287 isotope, which had a half- Seaborgium, for example, behaves quite like molybdenum and tungsten, with the volatile life of 5 seconds, which decayed to Element 112 (isotope 283) which did not decay for several oxydichloride S,C12 detected and ionic minutes. complexes fiydroxides and og7uorides) of hexavalent seaborgium in a liquid chromatography anal'yte. 2%us, seaborgium Jiis well Element 11 6 116 Discovered 2000 enough in its group to reafirm the valid@ of The Russian group claimed this etement by the Periodic Table for the elements in the bombarding curium with calcium. Isotope 292 fourth d-row. Likewise, for the next element decayed with a half-life of 50 milliseconds. (107) the volatility of bohrium oxychloride, BhO$Y,fits well into the sequence Tc0,Cl and This list is to be continued (and ReOgLIncredbly, the GSIgroup has extended studies as high as hassium (108), which falls must be verified!). .. . below osmium in the Periodic Table. Indeed, the property that earmarks osmium (the volatiliv of its tetroxide, see page 67), may be Chemical Research on Tran+sactinides. rejected to a certain extent in the chemistry of Despite the short lives and scarcity of the hassium oxide (Hs0.J. fr~ermiumelements, some research has been It appears that there exists an "actinide performed to determine their chemical beha- contraction" just as there is a "lanthanide vior. mese impressive experiments (performed contraction" (see pages 80, 102), but relativ- by GSI in Damtstadr) involve repetitive, short istic eflects lead to divergences for ruther- chemical experiments (less than 60 seconds fordium (104) and dubnium (105). For exam- Ion& that determine oxidation states, types of ple, the ionic radius of tetravalent rutherford- compounds formed, liquid chromatography ium is much larger than those for fetravalent behavior, and gas chromatography patterns. zirconium and hafiirtm (see page 99 where the The transfermium element is detected on an radius of zirconium and hafnizrm atoms are atom-by-atom basis fiom its radioactivity. The almost identical). Rutherfordium formsfluoride GSIgroup has been concentrating particularly complexes like zirconiunz and hafilium, but the on the superheavy elements, the transactinides chemistry is not the same. Hence, if the above lawrencium (103), the last element in the chemistry were known only as far as ruther- second f-row series of the Periodic Table. fordium (104), if would be drfficult to say ifthe trmactinides were "well-behaved" and should How i~rgeWill the Periodic Table lie below hacfirium, fantalum, tungsten, rhenium, Grow? Although initial attempts to produce md osmium jit the Periodic Table. Fortunafely, transuranium elements have been successfil, GSI has given to us a clearer picture of the the undertaking of the synthesis of higher chemishy of the transactinides and has located elements - the "superheavy elements" - has their proper place in the Periodic Table,just as proven to be challenging indeed Two major Seaborg origrgrnalIydid for the actinides them- problems are: insuflcient neutrons and the selves (see page 87). natural reprrlsion of miclei. ?be Darmstadt With this new undersfanding of how the pup has attempted to overcome the first superheavy elementsj2 into the Periodic Table, problem with neutron-rich isotopes, hut these the lafesfrendition of this Table ispresenfed in are sometimes difficult to synthesize in Figure 89 (page 113). This table reflects the su-cient quantity. nere is no obvious way to interplay of the behavior of the actinides and solve the secondproblem. Yet, the search con- the superheiny elements.

Theoretical Isle of Stability

Elements with Z> 99 so far discoveredfall in this region

140 150 160 170 180 190 Neutron number, N

Fiye88. In this illustrationthe theoretical regionsof nuclear stabilityare presented, that is, areasof predicted half-livesof over a year. Researchers havenot yet synthesizeda nucleus withthe correct proton numberZ and the neutronnumber N that should fall directlyon the "Isle of Stability." Until a means is discovered to producesuch nuclei, we will never know if the "Isle of Stabilitynreally exists.There are promisinghints, however,with nuclei that come close to this "Islen- for example, somesuperheavy elements have half-livesmeasured in secondsand even minutes. Somescientists hope that half-livesof elementsdirectly on the "Isle of Stabilitynmay be measured in thousandsof years. times, if only to test the theoretical "Isle of Stability" -perhaps with an atomic ntmber of 114 a~tda neutron number of 184 -- that has been predicted by several scientisfs. In nature, synthesis of heavier atoms requires a high fluxof neutrons. ?'%iscondition did not exist during the "Big Bang" and only light elements were formed at the creation of the universe - mostly hydogen and helium. me interior of stars can produce medium elements. Heavy elements are created in the "r- process" of supernovae explosions where an incredible firy of neutrons is created. Hence, we on earth can thank some past supernova, somewhere and sometime in the past, for the supply of our thorium, uranium, and other heavy elements an firth. Some models place this supernova about 5 billion (5 x 109)years) ago. In &ition to our terrestrial thorium and uranium, our ancient mother strpemova also produced plutonium, americium, curium, einsteinium, etc., which have all disappeared since the creation of the earth 4.6 billion (4.6 x 109) years ago. Most probably the supernova also produced atomic numbers above 100 -- but just how far above? Ifthere is an ''Me of Stability, " then why don't we see evidence of superheavy elements in nature? Is it becatae the 'h process"daes not produce them, or because they are simply not stable enough? Some scierliists believe that if we were able to synthesize a nucleus with the correct proton number and neutron number, we might have an element with incredibIy long half-lives, years or even thousam& of years in magnitude! me problem, of course, is$nding a way to load up a nucleus with a niflciently large number of neutrons while keeping the nucleus thermally relaxed (THELATEST) PERIODIC TABLE OF THE ELEMENTS

H 1 Li Be BCNO 3 4 5678 Na Mg Al Si P S 11 12 13 14 15 16 K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 ------Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 Cs Ba :La* Hf Ta W Re 0s IT Pt Au Hg TI Pb Bi Po 55 56 =57 72 73 74 75 76 77 78 79 80 81 82 83 84 Fr Ra %c** Rf Db Sg Bh Hs Mt 110 113 114 ? 87 88 i89.I 104 105 106 107 108 109 I II I Ce PI Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb lu 111111 58 59 60 61 62 63 64 65 66 67 68 69 70 71 I Lanthanides*

Figure 89. The latest PeriodicTable of the Elements. Relativisticeffects in the electronic shellsmay lead to surprisesin the chemical behaviorof the superheavyelements above lawrencium(103). In this rendition of the PeriodicTable, the actinides have been placed above the lanthanides to show their relationshipwith the superheavy elements. Thc actinides are manged in descendingstair steps, starling directly below nttherfordiurn(1 04), to reflect the observed behaviorof 104 and I05 sometimeslike 90 and 91, respectively:rutherlbrdiurn (104) in aqueous solutionsbehaves more like thorium in certain circumstances.;likewise, dubnium (105) is non-tantalumlike in aqueous solutions,but is similar to niobium and protactiniumin certain chemical environments.Starting with seaborgiurn(106), chemical behavior more closely resemblesthe elements dillyabove the superheavyelements and less like the actinides - that is, Sg is like W, Bh is like Re, and Hs is lie0s.

EPILOGUE

uring the past several thousand years of these particles may explain the very creation scientists have worked on a labor of of the universe itself. It appears that the love to present a portrait of the portrait is not yet finished. fundamental stuff of our chemical world. Each All of this is driven by curiosity of Man brush stroke has contributed to allow a filler to answer the physical riddles of the Universe. understanding of how our universe is made up. The same inquisitiveness that drove the We know that all matter is made up of atoms alchemist to toil over his crucible, the miner to - the word is taken from the Greek atornos pick up a nugget here and there and wonder for "indivisible" - and we have arrived at our what this new glistening rock really was, the quest of comprehending how these atoms nuclear chemist to split the atom - is reflected assemble and rearrange to transform in the modem scientists as he ponders over substances into others. Our heritage is rich, sprays of exotic particles that spew from and we see far. collisionsof relativistic leptons and baryons. It Now scientists are telling us that the is as if we are now analyzing the condiments atoms themselvesare made up of yet smaller in the kitchen itself, tearing each spice apart particles - quarks. The recent discovery of into its constituent flavors. Scientists are the "topn quark completes for the nuclear suggesting that they may even tackle the scientists an orderly coIlection of these cur- question of why matter exists at all. This iosities. They tell us that unlocking the secrets universe is indeed full of wonders.

BIOGRAPHICAL SKETCHES

Abelson. Philip Hauge Abelson (19 13- ). Andrada. See de Andrada. Physical chemist who proposed gas diffusion process for separating U-235 from U-238; Arfwedson. Johan August Arfwedson (1792- collaborated with McMillan in the discovery of 1841). Officerat the Royal Bureau of Mines at neptunium. He was later director of the Stockholm who discovered lithium by noting Geophysics Lab of the Carnegie Institution. a loss of weight in the analysis of petalite (lithium aluminum silicate). He performed this Achard. Franz Carl Achard (1753-1 821). work with Berzelius, Professor of chemistry at the Berlin Academy who discovered how to fabricate implements Aristotle (384-322 B.C.). Greekphilosopher of platinum by fusing it with arsenic. who was a pupil of Plato, the tutor of Alexander the Great, and the author of works Agricola. Georgius Agricola (1494-1555). on logic, metaphysics, ethics, natural sciences, German metallurgist who wrote De Re politics, and poetics. He profoundly influenced Metallica,a famous Latin reference on mining Western thought in his philosophical system, and metallurgy, which was translated into which included rational inquirybased on logic. English by Mr. and Mrs. Herbert Hoover. In He was the author of the four principles of this work Agricola included a description of fire, earth,water, and air. metals known at that time, including early references to bismuth, antimony, zinc, arsenic, Arkel. See van Arkel. fluorspar, and even cobalt ores. Arrhenius. Carl Axel Arrhenius (1757- Allison. Fred Allison (1 882-1974). Professor 1824). Swedish chemist and mineralogist who of physics at the Alabama Polytechnic Institute collected gadolinite (originally called ytterbite) (Auburn University) who with his "magneto- at the Ytterby Mine in Sweden. This rich optic method of chemical analysisn claimed the sample of rare earths started the search for the discovery of elements 85 ("aIabamineW)and 87 rare earths. ("virghium").These findings have never been verified or reproduced, Irving Langmuir Bacon. Roger Bacon (12 14-1292). English included these examples in his discussion of friar, scientist, and philosopher whose Opus "Pathological Science, " Majus (1267) argued that Christian studies should encompass the sciences, since science Alter. David Alter (1807-188 1). American reveals the Creator in the Creation and all Nis physician, physicist, and inventor who studied Works. the spark spectra of metals and gases. With great far-sightedness he predicted that some Balard. Antoine-JCrbme Balard (1802- day scientists would be able to identify 1876). Professor of chemistry at the Sorbonne elements in the stars. and the College de France who earlier discovered bromine in brines while a Lecturer at Montpellier , France. Bobr. Niels Henrik David Bob (1885-1962). Professor of theoretical physics at the Becher. Johann Joachim Becher (1635- University of Copenhagen. He had worked 1682). German chemist and physician who with Ernest Rutherford at the University of founded the phlogiston theory. Manchester. Bohr adopted Planck's quantum theory to Rutherford's model for atomic Becquerel. Antoine-Henri Becquerel(1852- structure; thereby he defined the structure of 1908). French physicist who discovered the atom by describing the quantized states of radioactivity when he observed that uranium the electrons, and how this structure gave rise salts could expose photographic plates. to the Periodic Table of the Elements.

Berg. Otto Berg (1874-?). Collaborator at Boisbaudran. See de Boisbaudran. Werner-Siemens Laboratory at Berlin-Charlot- tenburg. Discovered rhenium with Tacke and Bonn. Johann Bohn (1640- 171 8). Professor Noddack, of anatomyand therapeutics in Leipzig who in addition to anatomical researches investigated Berzelius. Jons Jacob Be~zelius(1 779- 1848). salts and acids. Professor of chemistry and medicine at the Stockholm medical school who discovered Bothe. Walter Bothe (1891-1957). Director selenium and ceria, and isolated silicon, of the Institute of Physics at the University of thorium, and zirconium. Berzelius accurately Geisen. Bothe (with H. Becker) bombarded determined the atomic weights of elements beryllium with helium atoms and observed a known at that time, necessary for the hard radiation (which was later found to be development of the Periodic Table. Berzelius composed of neutrons), produced many famous scientists - Wiihler, Rose, Mosander, Sefstriim, and Arfwedson. Boyle. Robert Boyle (1627-169 1). British chemist and physicist. Famous for his research Black. Joseph Black (1'728-1799). Professor on gases ("Boyle's Law"). Independently of chemistry at GIasgow, Scotland, who discovered phosphorus. Wrote "The Sceptical characterized "fixedair" (carbon dioxide) and Chymist"in which he discussed criteria for an differentiated between magnesia and lime. He "element." showed carbondioxide to be the agent that converts caustic alkalis into mild alkalis (i,e,, Brandt. Georg Brandt (1694- 1768). Swedish changesNaOH and KOH into the carbonates). chemist and physician who discovered cobalt.

Blomstrand. Cbristi Wilhelm Blomstrand Brauner. Bohuslav Brauner (1855-1935). (1826- 1897). Professor of chemistry and Professor of chemistry at the Bohemian mineralogy at the University of Lund, University in Prague who determined accurate Sweden. He prepared the first metallic atomic weights. He determined that the value niobium by reacting the chloride with for tellurium was actually greater than that of hydrogen. iodine, This pointed out that the periodic table should truly be based on chemical properties Boer. See de Boer. rather than solely on atomic weights. From his atomic weight determinations he correctly one hundred years later to be argon). placed lanthanum (which Mendeleev had Cavendish never relinquished the phlogiston mislocated in the periodic table). He suspected theory, despite his genius and the over- from spectroscopic studies that didyrniawas whelming evidence furnished by Lavoisier, actually a mixture of rare earths. Cbadwick. Sir James Chadwick (1891- Brownrigg. Dr. William Brownrigg (171 1- 1974). Professor of physics at the University 1800) British scientist who contributed of Liverpool. Chadwick discovered the important works on carbon dioxide, and whom neutron by bombarding beryllium with alpha Benjamin Franklin had visited and consulted. particles, With Sir William Watson, he reported the new metal from the New World, platinum. Chancourtois. See de Chancourtois.

Bunsen. Robert Wilheh Bunsen (1811- Charlemagne (768-814). The greatest of 1899). Professor of chemistry at Heidelberg Medieval kings, King of the Franksand University who invented the Bunsen burner, founder of the first empire in western Europe which emitted a blue flame rather than yellow. after the fall of Rome. His court at Aix-la- With Kirchhoff he developed spectroscopic Chapelle became the center of a cultural analysis using his flame technology with which rebirth in Europe, known as the Carolingian they discovered cesium and rubidium. Renaissance. Charlemagne created schools in cathedrals and monasteries which developed Bussy. Antoine-Alexandre-Bmtm Bussy in to Universities. (1794-1882). Professor of chemistry at the hole de pharmacie in Paris who prepared Cleve. Per Teodor Cleve (1840- 1905). magnesium by reacting its salts with metallic Professor of chemistry at Uppsala who potassium to obtain a fused form of the metal. discovered thulium and holmium. This method was patterned by many others in the preparation of various metallic elements. Corson. Dale Raymond Corson (1914- ). NucIear physics staff member at the Los Casciarolo. Vincenzo Casciarolo (early Alarnos Science Laboratory, then professor of 1600s). Shoemaker and alchemist in Bologna physics at Cornell University. Corson was a who discovered uBologna stone," barium codiscoverer of astatine (with Segri3 and sulphate samples from his locality that could Mackenzie). be made to fluoresce. Interest in this mineral was intense and led to discovery of baryta. CoryeU. Charles Dubois CoryelI (1912- 1971). Professor of chemistry at the Cavendish. HenryCavendish (1731-1810). Massachusetts Institute of Technology. With English chemist and physicist who discovered his assistants Marinsky and Glendenin he "inflammable air" (hydrogen). He conducted discovered promethium while at the Clinton very precise experiments of gases and Laboratories, soon to become the Oak Ridge independently discovered nitrogen. He also National Laboratory. observed a small amount of inert gas as a constituent of the atmosphere (which proved Coster. Dirk Coster (1 889-1950). Professor this method Crooks identified thallium and of physics at the Royal University of Gronigen proved that certain solar spectral lines were who (with de Hevesy) discovered hafnium at identical with those of terrestrial helium, thus the Niels Bohr Institute. establishing the practicality of stellar spectral analysis. He also realized that certain atoms Collet-Descotils. Hippolyte Victor CoUet- had identical chemical properties but different Descotils (1773- 18 15). French chemist who atomic weights (as early as 1886), and thus fist noticed red salts of platinum(which were of anticipated the concept of isotopes. iridium). He was the chemist whose erroneous analysis persuaded del Rio that his new element Curie. Marie Sklodowska Curie (1867- (vanadium) was merely chromium. 1934). Professor of physics at the University of Paris who with her husband Pierre Courtois. Bernard Courtois (1777- 1838). discovered polonium and radium. Mme. Curie Dijon, French pharmacist who discovered was the fist person to receive the Nobel Prize iodine in seaweed. twice.

Cranston. John Arnold Cranston (1891- Curie. Pierre Curie (1859- 1906). Professor 1972). Lecturer at the Royal Technical Col- of physics at the Sorbonne who with his wife lege, Glasgow . Codiscoverer of protactinium Marie discovered polonium and radium. He (eka-tantalum) with Soddy and Fleck. studied magnetic properties as a function of temperature (the Curiepoint is the temperature Crawford. Adaim Crawford (1748-1795). at which a substance loses ferromagnetism). Professor of chemistry at WooIwich, and physician at St. Thomas's Hospitai in London, Dalton. John Dalton (1766-1844). English who investigated minerals from Strontian, Quaker chemist who taught mathematics and Scotland, and proposed an earth separate and physics at New College, Manchester, England. intermediate between "calcareous and In his New astern of Chemistry (three parts: ponderous spars" (i.e., calcium and barium 1808, 1810, 1827) he explain how atoms can minerals). Discoverer of strontia, he be used to explain chemical reactions. He characterized it and was the first to recognize postulated a one-for-one combination of atoms it as a distinct element. to demonstrate specific summations of weights of the elements to form compounds. Dalton Cronstedt. Axel Fmdrik Cronstedt (1722- was colorblind and scientifically described this 1765). Swedish chemist and mineralogist who malady. Red-green colorblindness is some- discovered nickel. He also discovered cedte, times known today as "daltonism." the mineral that proved to contain ceriumand other rare earths. Davy. Sir Humphry Davy (1778-1829). English professor at the Royal Institution who Crooks. Sir Wiam Crooks(1832-1919). pioneered electrolysis for the preparation of Professor at the Royal College of Chemistry in reactive metallic elements. He dso invented London. He shared with Bunsen, Kirchhoff, the safety lamp for miners. Davy breaks the and de Boisbaudran the honor of establishing record for number of natural elements dis- the science of spectroscopic analysis. Using covered by one person: potassium, sodium, calcium, barium, strontium, magnesium, and de Fourcroy. Antoine-Fran~oisde Fourcroy boron (this list does not include elements (1755-1809). French chemist who, with beyond uranium; this honor goes to Ghiorso, collaboration with Lavoisier, Guyton de who discovered even more of the transuranium Morveau, and Berthollet developed the new elements). chemical nomenclature, He is considered by some to be an independent discoverer of de Andrada. Joz6 BonifAcio de Andrada e iridium. Silva (1763- 1838). Brazilian scientist who discovered petaIite and spodumene (lithium de Hevesy. George Charles de Hevesy (1889- minerals) during a tour of Europe, 1966). Hungarian chemist who codiscovered hafnium with DirkCoster. Hevesy took Bohr's de Boer, Jan Hedrick de Boer (1899- 1971). recommendation that hafnium would be Dutch chemist at Eindhoven, later Professor of discovered with zirconium ores; the work was chemistry at the University of Delft. With van done at the Niels Bohr Institute. Arkel, he developed a method of preparing pure metals using the iodide or crystal bar de Marignac. Jean-Charles Galird de process; first prepared metallic hafnium in Marignac (1 817- 1894). Professor of chem- 1925. istry at the University of Geneva, Switzerland, who discovered ytterbia and gadolinia and who de Boisbaudran. Lecoq de Boisbaudran conducted additional important research on the (1838-1912). French chemist who discovered rare earths. He proved niobium and tantalum gallium, samarium, and dysprosium. He were not identical by separating their acids. developed methods of separating the rare earths, thereby greatly untanghg the de Morveau. Baron Louis-Bernard Guyton confusion regarding this group of elements. He de Morveau (1737-1816). French chemist and also developed methods of spectroscopy which lawyer who worked with Lavoisier to develop he used to identify these eIements. With the new chemical nomenclature. He was from Bunsen, Kirchhoff, and Crookes, he is Dijon and knew the Courtois family. regarded as one of the founders of spectroscopic analysis. de UUoa. Don Antonio de UUoa (1716- 1795). Spanish scientist and explorer who described de Chamourtois. Alexandre E. Beguyer de platinum during his voyages to South America. Cbancourtois (1 820- 1886). Professor of He was responsible for bringing back the frrst geology at the hole Sup6rieure des Mines in cinnamon and rubber trees to the Old World. Paris who devise the spiral periodic arrangement of the elements, or the "telluric Debierne, Andre Louis Debierne (1874- screw. " 1949). French chemist, and assistant to Mme. Curie at the University of Paris, who de Elhuy ar, Fausto de Ebuyar (1755-1833) discovered actinium as a trace component in and Don Juan Josh de Ebuyar (1754-1796), pichblende. With Mme. Curie he isolated pure Spanish brothers who produced metallic radium in 1910. He succeeded Madame Curie tungsten at their Basque Seminary,in Bergara, as director of the Curie Institute in Paris. Spain. Descotils. See Collet-Descotils. by Ernest Rutherford to be the elememental gas radon (originally called "niton"). del No. Andr& del Rio (1764-1849). Professor of mineraology at the School of Draper. John W. Draper (1 8 11-1 882). First Mines in Mexico who discovered vanadium President of the American Chemical Society. (originally called "erythronium"). This Professor at Wampden-Sidney College, Virgin- discovery was later confirmed for the Old ia, then New York University, he conducted World by Sefstrlim. research in phosphorescence and photography. He first proposed spectroscopy as a method for Delafontaine. Marc Delafontaine (1 837- studying the chemical composition of stars, f 91 1). Swiss chemist at the University of Geneva who studied under de Marignac and Duhamel. Henri-Louis Duhamel du conducted studies on the rare earths. Monceau (1700- 1782). French chemist and agriculturalist who helped distinguish between Demarpy. Eugkne-Anatole Demarpy mineral alkali (sodium) and vegetable alkali (1852-1904). French chemist whodiscovered (potassium) by showing the former is found in europium. He also proved spectroscopically salt, Glauber's saIt, and borax, and the latter the discovery of radium by the Curies. is concentrated in plants.

Democritus (460?-370? B.c.). Greek philo- Ekeberg. Anders Gudaf Ekeberg (1767- sopher who proposed the existence of atoms. 1813). Swedish chemist and mineralogist, at the University of Uppsala, who discovered Deville. Henri Sainte-Claire Deville (1818- tantalum. 1881). Professor of chemistry at the University of Besaqon, then at the &ole Normale Elhuyar. See de Elhuyar. Sup6rieure. He prepared sodium on a commercial scale, and used this sodium to Fajam. Kaisii Fajans (1 887- 1975). prepare pure samples of silicon and aluminum, Professor of physical chemistry at Karlsruhe, Munich, and then at the University of Dobereiner. Jobam Wolfgang Dobereiner Michigan, who was involved with the (1780- 1849). Professor of chemistry at Jena, determination of the evolutionary sequence of Germany, who recognized triadrof elements. radioisotopes. He was codiscoverer of In each triad the middle element had an atomic protactinium (brevium, or uranium X3,with weight midway between the other two, and all Otto H. Glihring. three appeared to have similar properties. This was an important step toward the discovery of Fleck. Sir Alexander Fleck (1889-1968). the periodic table. Dlibereiner's most famous Advisor and counciI member of national safety findingwas the catalytic action of platinum and research committees in Great Britain, who (ignition of hydrogen over spongy platinum). was involved with the determination of the evolutionary sequence of radioisotopes. He Dorn. Friedrich Ernst Dorn (1 848-19 16) was codiscoverer of protactinium (eka- Discoverer of 'radium emanation," which he tantalum) with Soddy and Cranston. did not understand but which was later shown Flerov. Georgu Nikolaevitch Flerov (1913- Ghiorso. Albert Ghiorso (19 15- ). 1990). Head of the Laboratory of Nuclear Codiscoverer of elements 96-106 at the Reactions at Dubna, Russia; discovered several University of California, Berkeley. Working transuranium elements. with Seaborg, Ghiorso developed the techniques for isolating and proving the existence Fourcroy. See de Fourcroy. of short-lived species produced by the cyclotron. Ghiorso holds the record for the most Fraunhofer. Joseph Fraunhofer (1787- elements discovered (over 10). 1826). German physicist who invented the spectroscope with which he observed dark Giesel. Friedrich Otto Giesel (1852-1927). lines in the sun's spectrum ("Fraunhofer Research scientist at the Quinine Works of lines"). Bmunschweig, Germany. Although GieseI discovered actinium three years after Gadolin. Johan Gadolin (1760-1 852). Debierne, he is considered an independent Professor of chemistry at the University of discoverer of the element (in 1902). Giesel Abo, Finland, who discovered yttria. He discovered that a magnet deflects beta rays. conducted a thorough study of the rare earth minerals from Ytterby, Sweden. Glauber. Jobam Rudolph Glauber (1604- 1670). German chemist who studied salts and Gahn. Johan Gottlieb Gahn (1745-1818). acids, He characterized and named Glauber's Swedish chemist who discovered manganese. salt (sodiumsulfate hydrate) and suggested its He and ScheeIe concluded that baria was a used as a medicine, distinct earth. Gleadenin. Lawrence Elgin Glendenin Gay-Lussac. Louis-Joseph Gay-Lussac (1918- ) Codiscoverer of promethium (with (1778-1850). Professor of chemistry at the Coryell andMarinsky) at Oak Ridge National hole Polytechnique and at the Jardin des Laboratory; he later joined Argonne National Plantes in Paris who is best known for his law Laboratory, Illinois. of combining laws of gases. With Thenard he prepared boron. Gmelin. Leopold Gmelin (1788- 1853). Professor of chemistry and medicine at Geber. Abu Mum Jabir ibn Hayyan. (eighth Heidelberg University. He prepared pure century?). Arabian alchemist and scholar. selenium from fuming sulfuric acid and Geber wrote "Invention of Verity, or demonstrated the element originally came from Perfection," and other very influential works pyrite. which described the art of chemistry at the time. Geber represents the indispensable Gohring. Otto H. Gohring. See Fajans. contribution of Arabian afchemy to Europe, where it developed during the Renaissance. Gregor. Reverend William Gregor (1 761- Since a greatdeal of alchemy was unintelli- 18 17). English clergyman who discovered gible to the layman, his name becamesynony- titanium in a black, magnetic sand from the mous with nonsensical writing - hence &he Menachan vaIley in his own parish. term "gibberish. " Grosse. Aristid V. Grosse (1905- ). A Heroult. Paul-Louis-Toussaint H6roult native of Riga, Russia, worked on the (1863-1914). French metallurgist who designed Manhattan Project and later was head of the and invented various electric furnaces used in Research Institute at Temple University; first metallurgy. He discovered a cheap process for prepared protactinium oxide and metallic producing aluminum in a manner analogous to protactinium, Gross strongly promoted Charles HaI1, but lost credit as Hat1 had American science to ensure its supremacy over already applied for the patent. He was Director Russian science. of the SociCtk ElectrornCtallurgique Franqais at Forges, France. Hahn. Otto Hahn (1 879- 1968). Professor of chemistry at the University of Berlin and Hevesy. See de Hevesy. President of the Max Planck Society for the Promotion of Science who was codiscoverer Hiiinger. Wielrn Hisinger (1766- 1852). (with Lise Meitner) of protactinium and of Swedish mineralogist and geologist who nuclear fission - that neutron irradiation of owned the Riddarhytta mine where cerite was uranium and thorium by neutrons split these discovered. atoms. Hjelm. Peter Jacob Hjelm (1746-1813). Hall. Charles Martin Hall (1 863- 19 14). Assay Master of Royal Mint at Stockholm, American chemist, inventor, and philanthropist The best of friends with ScheeIe, it was his who discovered a cheap process for producing furnace that was used to produce elemental aluminum from cryolite. He developed this molybdenum. process when only a student at Oberlin College. Homberg. Wilhelm Homberg (1652-1715). Germanphysician, chemist, and lawyer who Ham. Robert Hare (1781-1858). Professor of prepared boric acid ("sedative salt"). Homberg chemistry at the University of Pennsylvania became interested in science in Magdeburg who developed a method of melting platinum when Otto von Guericke performed his famous by use of his oxy-hydrogen blowpipe. "Magdeburg miracles" with the evacuated hemispheres which sixteen horses could not Hatchett. Charles Hatchett (1765- 1847). separate. English chemist who discovered niobium (columbium) through a careful analysis of a Hope. Thomas Charles Hope (1766- 1844). mineral specimen from New England. Professor of chemistry at Edinburgh Univer- sity, Scotland, who indepently of Crawford buy. Rent!- Just Hauy (1743- 1822). French distinguished barytaand strontia, He was one mineralogist who discovered the basic laws of of first chemists in Great Britain to espouse crystallography. He used this approach to Lavoisier's views on eIements and combustion. demonstrate that the crystals of beryl and emerald are geometrically equivalent, leading Hopkins. B. Smith Hopkim (1873-1 952). to Vauquelin's proof that they were chemically Professor of chemistry at the University of identical. Illinois who claimed the discovery of element 61 and named it "illinium"; the discovery was never verified. and performed critical analyses on ceria.

Humboldt. Baron Alexander von Humboldt Klaus. Karl Karlovich Klaus (1796-1864). (1769- 1859).German naturalist and traveler. Professor of chemistry at the Universities of Humboldt refused to grant del No priority for Dorpat , Estonia, and Kazan, Russia, who the discovery of vanadium, and European discovered ruthenium. Although previous chemists followed HumboIdt's lead. It was investigators probably had isolated crude many years before del Rfo got proper credit mixtures containing the metal (Sniadecki and for the discovery. Osann), Klaus prepared the fist pure sample and is credited with the discovery. James. Charles James (1880-1928). Professor at New Hampshire and independent discoverer Lagrange. Joseph-Louis Lagrange (1736- of lutetium. He worked out a detailed, 1813). French mathematician who formulated efficient methods for separating the rare the caIculus of variations, and who mourned earths. Lavoisier's death.

Janssen. Pierre-Jules-CQar Janssen (1824- Larny. Claude-Auguste hmy (1820-1878). 1907). French astronomer, director of the President of the SociM Chimique de France astrophysical observatory at Meudon, who first who first prepared a sample of thallium. He observed the yellow helium line in the studied its compounds and discovered they spectrumof the sun. were very poisonous.

Joliot. Jean-Fr4dbric Joliot (1900- 1958). Lavoisier. Antoine Laurent Lavoisier (1743- Chemist at the Curie Institute in Paris; 1794). "The Father of Modern Chemistry." He husband of Mme. Joliot-Curie, was a French tax-collector who conducted chemistry experiments as an avocation. Being Joliot-Curie. Wne Joliot-Curie (1 897- 1958). an accountant, he believed the ledger should Daughter of Pierre and Marie Curie. With her balancein chemistry as well as in business and husband Jean she investigated important formulated the Law of Conservation of Mass. nuclear transmutation reactions. He is principally known, in his Traite' de Chernie in 1789, for overthrowing the Kirchhoff. Gustav Robert Kirchhoff (1 824- phlogiston theory by postulating the correct 1887). Professor of physics at Heidelberg and elements (instead of fire, earth, water, and Berlin who with Bunsen lay the foundation for air). He based this treatise on extensive spectroscopic analysis, With Bunsen he experimentation incIuding the reaction of discovered cesiumand rubidium by use of this hydrogen and oxygen (both of which he new technique. named) to form the compound (and not element!) water. Klaproth. Martin Hehrich Klaproth (1743- 1817). The first professor of chemistry at the Lawrence. Ernest Orlando Lawrence (190 1- University of Berlin. This distinguished 1958). Inventor of the cyclotron (University of German chemist discovered uranium and California, BerkeIey). zirconium, and verified tellurium and titanium, Leonardo da Vinci (1452-1519). Artist and quency systems for accelerators. scientist of Florence, Edmous for his influential paintings and studies in anatomy, optics, Macquer. Pierre-Joseph Macquer (1718- hydraulics, and other areas of science. He was 1784). Wrote Dictionary of Chemistry, well the most versatile genius of the Renaissance, known and full account of the status of filling notebooks with engineering and other chemistry in the late 1700s. Professor of scientific observations that were centuries medicine, he devoted a great deal of his ahead of their time. attention to chemistry, and carried out some work with Lavoisier. Liebig. Justus von Liebig (1 803- 1873). Professor of chemistry at Giessen, Germany Marckwald. Wily Marckwald. Professor at who conducted research in organic chemistry the University of Berlin; prepared metallic and agriculture, He is best known for his polonium in 1906. For this element he JustusLiebig's Annalender Chemie. proposed the name radiutellun'um.

Linck.Jobann Heinrich Linck (1675- 1735). Marggraf. Andreas Sigismund Marggraf Pharmacist at Leipzig who mistook nickel for (1709-1782). German chemist who recognized copper. alumina in clay and that magnesia was distinct from calcium compounds. He distinguished Lockyer. Sir Noman Lockyer (1836-1 920). between potash and soda and dramatically Director of the solar physics observatory of the demonstrated the difference between the two Royal College of Science at South Kensington. saltpeters - cubic saltpeter (NaNO,) gave a Lockyer proposed, from the observation by yellow flash in gunpowder and prismatic Janssen of a yellow line in the sun's spectrum, saltpeter (KNO,) gave a blue flash. that a new element had been detected. This element - helium - was not uncovered on Marignac. See de Marignac. earth until almost thirty years later. Marinsky. Jakob Akiba Marinsky (1918- Lomonosov. Mikhail Vasilyevich Lorno- ). Codiscoverer of promethium (with nosov (171 1-1765). Russian scientist who Coryell and Glendenin) at OakRidge National studied principles of heat and gases.He also as Laboratory. Later he was Professor of a geologist (who proposed a form of chemistry at SUNY Buffalo. uniformitarianism), a mineralogist (who proved the organic origin of coal, petroleum, Matthiessen. Augustus Matthiessen (183 1- peat, and amber) and an astronomer (who 1870). German chemist who with Bunsen discovered Venus had an atmosphere). He prepared lithium for spectroscopic analysis by founded the first chemistry laboratory in efectrolyzing lithium chloride. He later was Russia and founded the Moscow State Professor of chemistry at St. Mary's Hospital University. and St. Bartholomew's Hospital in London.

Mackenzie. Kenneth RossMackenzie (1 9 12- McMillan. Edwin Mattison McMillan (1907- ). Codiscoverer of astatine (with Segri3 1991). Professor of physics at the University and Corson). At UCLA he developed radiofre- of California-Berkeley who with Philip Abelson discovered neptunium. He also (carborundum, silicon carbide, when found in developed the synchrotron. nature is called "moissanite").

Meitner. Lie Meitner (1878- 1968). Morveau. See de Morveau. Professor of chemistry at the University of Berlin who was codiscoverer (with Hahn) of Mosander. Carl Gustav Mosander (1797- protactinium and of nuclear fission. She fled 1858). Professor of chemistry and mineralogy Nazi Germany and continued her collaboration at the Caroline Institute, Sweden, andcurator with Hahn by correspondence. She is regarded of the mineral collections at the Stockholm to have been entitled to sharing the Nobel Academy of Sciences, who discovered Prizewith Hahn, since she was of equal status lanihana, didymia, erbia, and krbia. Mosander at the university and shared fully in the was the first to appreciate the complexity of scientific contribution. the rare earths when he extracted the first two rareearths from cerium andthe latter two rare Mendeleev. Dimitri lvanovich Mendeleev earths from yttria. (1834-1 907). Professor of chemistry at the University of St. Petersburg, famous for his Moseley. Henry Gwyn Jeffreys Moseley periodic table of the elements. Meyer was a (1887-19 15). Ehglish physicist who discovered codiscoverer of the periodic arrangement of the relationship between the atomic number of the elements, but Mendeleev's approach - a an element and the frequency of its X-ray descriptive table based on chemical properties spectrum. On the basis of his work a truly and valence - proved more useful and even numerical periodic table could be constructed. allowed the prediction of new elements. He was killed in World War I at the age of 27.

Meyer, Julius Lothar Meyer (1 830-1895). Newlands. John Alexander Reina Newlands Professor of chemistry at Breslau and (1837-1898). Professor of chemistry at the Tiibingen. Codiscoverer with Mendeleev of School of Medicine for Women and at the City the periodic arrangement of the elements. of London College who discovered the "Law Meyer's approach was based more on physical of Octaves." This concept led directly to Men- properties, such as atomic volume and deleev's periodic table of the elements. electrochemical behavior, whereas Mendeleev's idea was to arrange the elements Nilson. LarsFredrik Nilson (1840- 1890). in a descriptive table reflecting their valence Professor of analytical chemistry at the patterns. Mendeleev's approach proved to be University of Uppsala and at the Agricultural more useful and he is generally credited with Academy at StockhoIm who discovered the concept of the modern periodic table. scandium by isolating it from the rare earths. Nilson also prepared titanium in pure form. Moissan. Henri Moissan (1852- 1907). Professor of chemistry at the hole de Noddack. Walter Karl Friedrich Noddack pharmacie and at the Sorbonne who discovered (1893-1960). Professor of chemistry at the fluorine by electrolyzing fluoride salts. With Philosophische Theulogische Hochschule, his electric furnace he investigated the Barnberg, Germany, and director of the Insti- synthesis of diamonds and other materids tute for physical chemistry at the University of Freiberg. Codiscoverer of rhenium (with his interested in rocksand helped contribute to a wife Ida Tacke, and Otto Berg) at Physika- systematic understanding of minerals, lisches-Technisches Reichsanstalt in Berlin. Paracelsus. Paracelsus Theophrastus Bombastus von Hohenheirn (1493-154 1). A Noddack. Ida Eva Tacke Noddack (1896- Swiss medical alchemist who used the art to 1979). Codiscoverer of rhenium (with her relieve human suffering. Paracelsus was an husband Walter Noddack, and Otto Berg). intriguing person, pompous but brilliant. His middle name migrated to the English language Occam. Wi of Occam (1285?-1349?) An as "bombastic," meaning pompous and preten- English scholastic philosopher who rejected tious. the reality of universal concepts and originator of "Occam's razor," a tenet holds that if there Peligot. Euggne Peligot (18 11- 1890). is not hard evidence to establish which Professor of analytical chemistry andglass- competing theoryshould be accepted, then the making at the Central School of Arts and simplest theory should be selected. Manufactures in Paris, who isolated uranium in elemental form. Olsted. Hans Christian Orsted (1777-1851). Physicist and chemist in Copenhagen who Perey. Maguerite Catherine Perey (1909- discovered the relationship between electricity 1975). Discoverer of francium, at the Curie and magnetism. He was also the first to Institute in Paris. prepare metallic aluminum. Perrier. Carlo Perrier (1 886- 1948). Osann. Gottfried Wilhelm Osann (1797- Professor of mineralogy at University of 1866). Professor of chemistry at the University Palermo, Sicily; codiscoverer of technetium of Dorpat, Estonia, who claimed to discover (with Segrk). The mineral pemerite, a three new metals from platinum: pluranium, complex silicate, was named after him. ruthenium, and polinium. It soon became clear that all samples were crude mixtures, and that Pliny the Elder (23?-79). Roman scholar who the ruthenium perhaps did contain some new wrote manyscientific and historical accounts, metal. Klaus, who later isolated ruthenium, including his great encyclopedia of nature, adopted Osann's name for the element. Historia Naturalis, which extensively deals with astronomy, geography, anthropology, Ostwald. Wielm Ostwald (1853-1932). physiology, zoology, botany, horticulture, Famous and popular professor of physical medicine, mineralogy, metallurgy, and art. chemistry of the University of Leipzig, active in research in chemical equilibrium and Pott. Johann Heinricb Pott (1692- 1777). reaction rates. He founded the Zeitschnyjiir Professor of chemistry in the Collegium physikalische Chemie, medicochirurgicum in Berlin who distinguished between limestone, gypsum, Paby. Bernard Palissy (15 lo?-1589). clay, and silica. French glassmaker and chemist who knew of "zaffer" or cobalt blue. Palissy was very Priestley . Joseph Priestley (1733- 1804). An Roscoe. Sir Henry Enfield Roscoe (1833- English minister who devoted his life to 1915). Professor of chemistry at the University scientific experiments after being inspired by of Manchester who prepared metallic a personal visit from Benjamin Franklin, He vanadium. He had worked with Bunsen in worked extensively with gases, discovered Beidelberg on spectroscopy; a famous "dephlogisticated air" (oxygen), and concocted photograph poses the trio Roscoe, Bunsen, and carbonated water as a refreshing beverage. Kirchhoff. Owing to his political views (sympathizer of the French and American revolutions), his Rose. Heinrich Rose (1795- 1864). German home and laboratory were destroyed by a mob pharmacist whose study of columbite and in 1791, and he emigrated to the United tantaIite showed niobium (columbium) and States. tantalum are different. It was he who gave the final nameto niobium. Raleigh. John William Strutt, Lord Raleigh (1 842-1919). Professor of physics at Rumford (Count Rumford). Benjamin Cavendish Laboratory, Cambridge University, Thompson (1753-1814). A RoyaIist During a molecular weight determination of American, a contemporary of Benjamin nitrogen, he puzzled over the slight (but real, Franklin,who founded the Royal Institution in and reproducible) difference between London. He was interested in heat, invented atmospheric nitrogen and that obtained from ingenious fireplaces and stoves, and from inorganic compounds. This observation led to observing the heat evolved from the boring of studies by Rarnsay that triggered the discovery cannons showed that heat is not a substance of the admixtured argon. but is generated through motion. He married Mme. Lavoisier in 1805 (who had been Ramsay. Sir William Ramsay (1 852- 19 16). widowed in 1794), but separated in 1809. Scottish chemist and physicist at the University at Glasgow and then at the University College, Rutherford. Ernest Rutherford (1871-1937). London. Prompted by Raleigh, he investigated Fit Baron Rutherford of Nelson; Professor of atmospheric fractions and discovered the inert chemistry at McGill University, then the gases neon, argon, krypton, and xenon. University of Manchester and finally at Cambridge. A New Zdander, Rutherford Reich. Ferdinand Reich (1799-1 882). classified radiation into alpha, beta, and Professor of physics at the Freiberg School of gamma types and discovered the atomic Mines who discovered indium. Reich, being nucleus. He was the first to characterize radon ~Iorblind,relied on Richter, his assistant, for fully and to recognize it as an element, and the spectral analysis. should well be credited with its discovery.

Richter. Hieroaymus Theodor Richter Rutherford. Daniel Rutherford (1 749- 18 19). (1824- 1898). Director of the Freiberg School Professor of botany at Edinburgh, Scotland, of Mines. WhiIe an assistant for Reich, he who discovered "phlogisticated air" (nitrogen). observed the indigo lines of indium. He was the uncle of Sir Walter Scott.

Rio. See del Rio. Samarski. Vasilii E. Samarski-Bykhovets Sefstrom. Nils Gabriel Sefstrom (1787- (1803-1870). Officer of the Russian Corps of 1845). Professor at the Caroline Institute of Mining Engineers who furnished several Medicine and Surgery and at the School of specimens for analysis that were rich in rare . Mines in Stockholm, Sweden, who redis- earths. covered vanadium (originally discovered by del KO). Schadel. Matthias Schadel (1948- ). Researcher at G3.1. (Gesellschaft fiir Segri?. Mlio Gino Segri? (1905-1989). Schwerionenforschung in Dmstadt) who has Discoverer of technetium at the Royal been successful in conducting chemical University of Palermo, SiIicy, Italy; experiments with heavy elements, notably codiscoverer of astatine (with Corson and seaborgium . Mackenzie) at the University of California- Berkeley. Scheele. Carl WilheIm Scheele (1742-1786). Swedish chemist and pharmacist who dis- Smith. J. Lawrence Smith (1818-1883). covered oxygen (independently with Priestly), American mineralogist and chemist who tungsten (tungstic acid), barium (baria), investigated the rare earths in sarnarskite (a molybdenum (by proving it was distinct from complex rare earth-uranium-iron titanate- graphite), and chlorine. The mineral scheelite niobate-tantidate). He dso verified Mosander's (CaW04) is named after him. In spite of his conclusions that yttria contained a mixture of far-reaching discoveries, he was a rare earths. phlogistonist to the end, and even considered his chlorine as being "dephlogisticated muriatic Suiadecki. Jedrzej Andrei Sniadecki (I768- acid." 1838). Professor of chemistry at the University of Vilno, Poland, who isolated a new element Schmidt. Gedtardt Carl Schmidt (1928- ). he called vestium.It is now clear that he had Professor of physics at the University of isolated a crude sample of ruthenium. Miinster, who independently discovered Confirmation was lacking and credit has not radioactivity of thorium in 1898 (as did the been given to him for the discovery. Curies). Schmidt did not continue his research in this area. Soddy. Frederick Soddy (1877-1956). Professor of chemistry at Glasgow, Aberdeen, Seaborg. Glenn T. Seaborg (1912-1999). and Oxford who showed that when a Professor of chemistry at the University of radioactive element ejects an alpha particle it California, Berkeley who discovered pluto- shifts two atomic numbers to the left in the nium, americium, curium, and other trans- periodic table, and when the element emits an uranium elements. Seaborg proposed that the electron it moves one atomic number to the elements starting with atomic number 90 right. This observation explained the creation belonged to a class analogous to the rare of radioactive isotopes. He is credited with the earths, instead of with the transition metals. codiscovery of protactinium (eka-tantalum), Seaborgium is the first element namedfor a with Cranston and Fleck. living person. Spedding. Frank Harold Spedding (1902- carbon dioxide). Tennant discovered that 1984). Developer of ionexchange methods for diamond was carbon by burning it and separation of lanthanides, andfor the actinides collecting the carbon dioxide in potash. during World War 11. Before Spedding, the rare earthscould not be obtained in pure form. Thenard. Louis-Jacques Thenard (1777- 1857). Professor of chemistry at the hole Stahl. Georg Ernst Stahl (1660-1734). Polytechnique in Paris who with Gay-Lussac German chemist, physician, and professor who he prepared boron. He also discovered elaborated and refined the theory of hydrogen peroxide. phlogiston, Often regarded as an "alchemist" because he believed in the old principles, Travers. Morris William Travers (1 872- nevertheless Stahl should be regarded as the 1961). Professor at the University of Bristol. first true chemist, because he proposed a self- Codiscoverer with Ramsay of neon, krypton, consistent theory that could be tested: His and xenon while at University College, theory was the beginning of the scientific London. method in chemistry. Woa. See de Ulloa. Stromeyer. Friedrich Strorneyer (1776- 1835). Germany pharmacist who discovered Urbain. Georges Urbain (1872-1938). French cadmium by noticing a yellow impurity in zinc chemist and President of the Socidte de Chimie preparations . who discovered and named lutetia (discovery honors are shared with Welsbach and James). Sylvius. Francis Sylvius de le Boe (1614- Urbain had spent years analyzing complex 1672). Dutch physician who developed the mixtures of rare earths, only to discover that "iatrochemicd" method of using drugs to analysis could be rapidly performed using the counteract disturbances in the body, most due, brand-new X-ray techniques of Moseley. he thought, to hyperacidity. From his name "sylvite" (KC1) is derived. He was the first to van Arkel. Anton Eduard van Arkel (1893- characterize tubercu~osis. 1976). Dutch chemist at Eindhoven, later Professor of chemistry at the University of Tacke. See Noddack. Leiden. With de Boer, he developed a method of preparing pure metals using the iodide or Talbot. Wiiam Henry Fox Talbot (1800- crystal bar process; first prepared metallic 1877). English physicist and pioneer in hafnium in 1925. photography. He was able to differentiate lithium from strontium even though both gave Vauquelin. Nicolas-Louis Vauquelin (1763- redflames. 1829). Professor at the hole Polytechnique and at the School of Mines in Paris who Tennant. Smithson Ternant (1761- 1815). discovered chromium and beryllium. Professor chemistry at Cambridge University who discovered osmium and iridium in von Reichenstein. Miiller von Reichenstein platinum residues. He studied under Black (1 740- 1825). Mining commissioner in Tran- (who performed the famous experiments on sylvania who discovered tellurium. von Laue. Max von Laue (1879-1960). crucibles. German physicist who studied crystals by the diffraction of X-rays.

Watson. Sir William Watson (17 15-1787). British physician and naturaIist who commun- icated Brownrigg's description of platinum to the Royal Society.

Weigel. Fritz Weigel. Professor at the University of Munich; first prepared metallic promethium.

Welsbach. Baron Auer von Welsbach (1858- 1929). Austrian chemist who separated didymia into praseodymium and neodymium. Welsbach invented the gas mantle known by his name, by impregnating mantle fabric with refractory thorium and cerium salts. He is credited with the independent discovery of lutetium, which he called "cassiopeium,"

Wier.Clemens Alexander Winkler (2838-1904). Professor of chemistry at the Freiberg School of Mines, Germany, who discovered germanium in the mineral argyrodite (Ag,GeS&.

Wohler. Friedrich Wohler (1800- 1882). Professor of chemistry at GBttingen who was famous for proving organic compounds did not possess a "vital force" by synthesizing urea from ammonium isocyanate. Wohler prepared aluminum, beryllium, and yttrium by reduction of their chlorides by metallic potassium.

Wollaston. William Hyde Wollaston (1766- 1828). English chemist and physicist who discovered palladium and rhodium. Wollaston discovered a process for making platinum malleable by the use of aqua regia, thereby allowing the facile construction of platinum ABUNDANCES OF ELEMENTS in the EARTH'S CRUST and OCEAN, and in METEORITES

Units. Values in the following tables are given in logarithm units of pprn (parts per million). In order to convert to ppm, to percentages, or to fictions, the reader may following the following operations. For ppm, take the antilog: pprn = antilog(tab1e value). For percentage, divide the antilog of the table value by lo4. For the fraction, divide the antilog of the table value by lo6.

Examples, using the values for the earth's crust: For hydrogen (H), pprn = antilog(3.1) = 1200 = 1.2 x lo4pprn % = antilog(3.1) + 10' = 0.12% fraction = antilog(3.1) + lo4= 0.0012 For gold (Au), pprn = antilog(-2.4) = 0.004 pprn % = antilog(-2.4) + lo4= 0.0000004% = 4 x lo-'% fraction = antiIog(-2.4) + lo6- 0.000000004 = 4 x lo-'

ABUNDANCES OF ELEMENTS IN THE EARTH'S CRUST (Logarithms of pprn values) H He 3.1 -2.1 Li Be BCNOFNe 1.3 0.4 1.0 1.3 2.3 5.7 2.8 -2.3 Na Mg Al Si P S CI Ar 4.4 4.4 4.9 5.4 3.0 2.4 2.1 0.5 K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr 4.3 4.6 1.3 3.8 2.1 2.0 3.0 4.8 1.4 1.9 1.7 1.8 1.2 0.7 0.2 -1.3 0.4 -4.0 Rb ' Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe 1.9 2.6 1.5 2.2 1-3 0.2 <-*O -3.0 -3.0 -2.0 - 1.2 -0.7 - 1 .O 0.3 -0.7 -3.0 -0.3 -4.5 Cs Ba La Hf Ta W Re 0s Ir Pt Au Hg TI Pb Bi Po At Rn 0.0 2.6 1.5 0.6 0.3 0.2 -2.3 -3.0 -3.0 -2.3 -2.4 -1.1 -0.4 1.1 -0.8 -9.7 <-20-12.4, Fr Ra Ac C-20 -6.0 - 9.3 Prn Sm Eu Gd Tb Dy Ho Et Trn Yb Lu e-20 0.8 0.1 10.7 0.0 0.5 0.1 **Actinides - Th Pa U - 1.0 -5.9 0.4

ABUNDANCES OF ELEMENTS IN THE EARTH'S OCEAN (Logarithms of pprn values)

Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu -3.4 -4.6 -4.0 -4.6 -5.4 -4.7 -5.5 -5.0 -5.4 -5.0 -5.8 -5.0 -5.7 ""Actinides - Th Pa U -3.1 -9 -2.5

ABUNDANCES OF ELEMENTS IN METEORITES (Logarithms of pprn values) m

I I Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu -0.7 -1.1 -0.5 -0.3 -0.5 -0.1 -0.6 -1.5 -0.7 -1.5 ""Actinides - Th Pa U ------1.4 - 2.0

The values above are for stony chondrites, the most common type of meteorite. In carbon chondrites, the elements marked with "t" may exist in much higher concentration: H = 4.5 pprn C = 4.7 pprn N = 4.6 pprn S = 4.9 pprn

ATOMIC AND MASS NUMBERS

ELEMENT SYM. NO. MASS Meitnerium Mendelevium Actinium Ac 89 227.0278 Mercury Aluminum Al 13 26.98154 Molybdenum Americium Am 95 (243) Neodymium Antimony Sb 5 i 121.76 Neon Argon Ar 18 39.948 Neptunium Arsenic As 33 74.9216 Nickel Astntinc At 85 (210) Niobium Barium Ba 56 137.33 Nitrogen Berkelium Bk 97 (247) Nobelium Beryllium Be 4 9.01218 Osmium Bismuth Bi 83 208.9804 Oxygen Bohrium Bh 107 (262) Palladium Boron B 5 10.8 1 Phosphorus Bromine Br 35 79.904 Platinum Cadmium Cd 48 112.41 Plutonium Calcium Ca 20 40.078 Polonium Californium Cf 98 (25 1) Potassium Carbon C 6 12.01 1 Praseodymium Cerium Ce 58 140.12 Promethium Cesium Cs 55 i 32.9054 Protactinium Chlorine CI 17 35.453 Radium Chromium Cr 24 5 1.996 Radon Cobalt Co 27 58.9332 Rhenium Copper Cu 29 63.546 Rhodium Curium Cm 96 (247) Rubidium Dubnium Db 105 (262) Ruthenium Dysprosium DY 66 162.50 Rutherfordim Einsteinium Es 99 (254) Samarium Erbium Er 68 167.26 Scandium Europium Eu 63 151.96 Seaborgium Fermium Fm 100 (257) Selenium Fluorine I: 9 18.998403 Silicon Francium Fr 87 (223) Silver Gadolinium Gd 64 157.25 Sodium Gallium Gn 3 1 69.723 Strontium Germanium Ge 32 72.61 Sulfur Gold Au 79 196.9665 Tantalum HaGlium Hf 72 178.49 Technetium Hassiurn Hs 108 (265) Tellurium Helium He 2 4.00260 Terbium Holmium Ho 67 164.9303 Thallium Hydrogen H I 1.0079 Thorium Indium In 49 114.82 Thulium Iodine I 53 126.9045 Tin Iridium Ir 77 192.22 Titanium Iron Fe 26 55.845 Tungsten Krypton Kr 36 83.80 Uranium Lanlhanum La 57 138.9055 Vanadium Lawrencium Lr 103 (262) Xenon Lead Pb 82 207.2 Ytterbium Lithium Li 3 6.94 1 Yttrium Lutetium Lu 7 1 174.967 Zinc Magnesium Mg 12 24.305 Zirconium Manganese Mn 25 54.9380 ISBN0-53b-b7397-2

Key to Periodic Table Icons 1. Hydrogen — burning dirigible (e.g., Hindenburg) 2. Helium — party balloons 3. Lithium — lithium carbonate pills for manic depressives 4. Beryllium — gyroscope in space (extremely light structural material) 5. Boron — borax 6. Carbon — coal 7. Nitrogen — ammonia 8. Oxygen — hospital oxygen 9. Fluorine — fluoride toothpaste 10. Neon — neon sign 11. Sodium — table salt 12. Magnesium — leaves (chlorophyll) 13. Aluminum — beverage cans 14. Silicon — glass (silicates) 15. Phosphorus — matches (red P in striking surface of safety matches) 16. Sulfur — volcano 17. Chlorine — chlorine bleach 18. Argon — light bulb (inert gas filler) 19. Potassium — banana (common alkali in plants) 20. Calcium — teeth (calcium phosphate) 21. Scandium — added to lamps to give natural sunlight appearance 22. Titanium — paint (titanium oxide) 23. Vanadium — tank (armor plate) 24. Chromium — chrome bumper 25. Manganese — manganese oxide battery filler 26. Iron — train engine 27. Cobalt — magnet (Alnico alloy) 28. Nickel — nickel coin (actually 3:1 Ni:Cu) 29. Copper — penny coin (pre-1983; modern pennies are copper-plated zinc) 30. Zinc — windmill (galvanized steel) 31. Gallium — semiconductor (gallium arsenide) 32. Germanium — rectifier (original transistor material) 33. Arsenic — insecticide 34. Selenium — exposure meter in camera (photoconductive effect) 35. Bromine — fire retardant (baby’s clothes) 36. Krypton — krypton bulb 37. Rubidium — found in coffee and tea (mixed in nature with potassium) 38. Strontium — fireworks (red color) 39. Yttrium — phosphors 40. Zirconium — neutron-transparent refractory for uranium reactors 41. Niobium — alloys for aircraft 42. Molybdenum — ingredient in high-strength steels 43. Technetium — radioactive tracer in the body 44. Ruthenium — electrical contacts 45. Rhodium — spark plug contact 46. Palladium — surgical instruments 47. Silver — silver coin 48. Cadmium — plating for screws and nuts 49. Indium — metal-to-glass seal in optics 50. Tin — coating for tin cans 51. Antimony — ingredient in pewter and mascara 52. Tellurium — blasting caps 53. Iodine — seaweed 54. Xenon — inert gas in strobes 55. Cesium — atomic clock 56. Barium — X-rays of digestive tract 57. Lanthanum — catalysis for petroleum refining 58. Cerium — lighter flint (Misch metal) 59. Praseodymium — oxides used to polish optics (along with Ce/La) 60. Neodymium — “didymium” (Nd/Pr) used for glassblowers’ glasses 61. Promethium — found in supernovae (not natural on earth) 62. Samarium — carbon arc high intensity lights 63. Europium — red phosphor in television sets 64. Gadolinium — laser discs 65. Terbium — phosphor in fluorescent lamps (blue) 66. Dysprosium — halogen lamps 67. Holmium — optics (calibration lines) 68. Erbium — pink coloring in ceramics 69. Thulium — radiation badges 70. Ytterbium — earthquake sensors 71. Lutetium — dating isotope in meteorites 72. Hafnium — refractory material 73. Tantalum — electronic capacitor 74. Tungsten — light bulb filament 75. Rhenium — electrical contacts 76. Osmium — pen points 77. Iridium — layer at KT geological boundary (extinction of dinosaurs) 78. Platinum — catalyst in auto emissions catalytic converter 79. Gold — pot of gold 80. Mercury — thermometers 81. Thallium — rodenticide 82. Lead — automobile storage battery 83. Bismuth — fuses 84. Polonium — antistatic brushes for film 85. Astatine — available only in minute amounts 86. Radon — collects in house basements 87. Francium — available only in minute amounts 88. Radium — formerly used as fluorescent paint in watches 89. Actinium — available only in minute amounts 90. Thorium — oxide used as refractory in gas mantles 91. Protactinium — available only in minute amounts 92. Uranium — atomic submarines 93. Neptunium — Neptune 94. Plutonium — atomic explosion 95. Americium — smoke detectors 96. Curium — Marie Curie 97. Berkelium — University graduate 98. Californium — California 99. Einsteinium — Albert Einstein 100. Fermium — Enrico Fermi, discoverer of nuclear chain reaction 101. Mendelevium — Dimitri Mendeleév 102. Nobelium — Alfred Nobel 103. Lawrencium — Ernest Lawrence, inventor of cyclotron 104. Rutherfordium — Ernest Rutherford, discoverer of atomic nucleus 105. Dubnium — Institute for Nuclear Research in Dubna, Russia, near Moscow (coat-of arms for Dubna) 106. Seaborgium — Glenn Seaborg, pioneer of transuranium elements at UC-Berkeley 107. Bohrium — Niels Bohr, who interpreted the atomic structure of the atom 108. Hassium — state of Hessen, Germany (Darmstadt, Institute for Heavy-Ion Research) (coat of arms for Hessen) 109. Meitnerium — Lise Meitner, codiscoverer of atomic fission 110. Darmstadtium — Darmstadt, Institute for Heavy-Ion Research (coat of arms for Darmstadt) 111. Roentgenium — Wilhelm Röntgen, discoverer of X-rays 112. Copernecium — Nicolaus Copernicus, formulated the heliocentric theory 113. Nihonium — from “Japan” in native language (seal of RIKEN, Rikagaku Kenkyusho, Research Institute near Tokyo) 114. Flerovium — Georgy Nikolayevich Flyorov, Russian physicst, founded the Joint Institute for Nuclear Research in Dubna, Russia 115. Moscovium — Moscow, Russia (coat of arms of Moscow) 116. Livermorium — Lawrence Livermore National Laboratory, nuclear science site in California 117. Tennessine — Oak Ridge, Tennessee, main research site of the Manhattan project (seal of Oak Ridge) 118. Oganession — Yuri Tsolakovich Oganessian, principle researcher of superheavy elements