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قراءة كتاب A Brief Account of Radio-activity
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A Brief Account of Radio-activity
A BRIEF ACCOUNT OF
RADIO-ACTIVITY
BY
FRANCIS P. VENABLE, Ph.D., D.Sc., LL.D.
PROFESSOR OF CHEMISTRY, UNIVERSITY OF NORTH CAROLINA
AUTHOR OF
"A SHORT HISTORY OF CHEMISTRY,"
"PERIODIC LAW," ETC.
D. C. HEATH & CO., PUBLISHERS
BOSTON NEW YORK CHICAGO
Copyright, 1917,
By D. C. Heath & Co.
IA7
PREFACE
I have gathered the material for this little book because I have found it a necessary filling out of the course for my class in general chemistry. Such a course dealing with the composition and structure of matter is left unfinished and in the air, as it were, unless the marvellous facts and deductions from the study of radio-activity are presented and discussed. The usual page or two given in the present text-books are too condensed in their treatment to afford any intelligent grasp of the subject, so I have put in book form the lectures which I have hitherto felt forced to give.
Perhaps the book may prove useful also to busy men in other branches of science who wish to know something of radio-activity and have scant leisure in which to read the larger treatises.
It is needless to say that there is nothing original in the book unless it be in part the grouping of facts and order of their treatment. I have made free use of the writings of Rutherford, Soddy, and J. J. Thomson, and would here express my debt to them—just a part of that indebtedness which we all feel to these masters. I wish also to acknowledge my obligations to Professor Bertram B. Boltwood for his helpful suggestions in connection with this work.
CONTENTS
| CHAPTER I | |
| DISCOVERY OF RADIO-ACTIVITY | PAGE |
| The beginning—Radio-active bodies—An atomic property—Discovery of new radio-active bodies—Discovery of Polonium—Discovery of Radium—Other radio-active bodies found | 1 |
| CHAPTER II | |
| PROPERTIES OF THE RADIATIONS | |
| Ionization of Gases—Experimental confirmation—Application of electric field—Size and nature of ions—Photographing the track of the ray—Action of radiations on photographic plates—Discharge of electrified bodies—Scintillations on phosphorescent bodies—Penetrating power—Magnetic deflection—Three types of rays—Alpha rays—Beta rays—Gamma rays—Measurement of radiations—Identifications of the rays | 7 |
| CHAPTER III | |
| CHANGES IN RADIO-ACTIVE BODIES | |
| Radio-activity a permanent property—Induced activity—Discovery of Uranium X—Conclusions drawn—Search for new radio-active bodies—Methods of investigation—Nature of the radiations—Life-periods—Equilibrium series | 17 |
| CHAPTER IV | |
| NATURE OF THE ALPHA PARTICLE | |
| Disintegrating of the elements—Identification of the rays—The alpha rays—Alpha rays consist of solid particles—Electrical charge—Helium formed from alpha particles—Discovery of Helium—Characteristics of Helium—Table of constants | 25 |
| CHAPTER V | |
| THE STRUCTURE OF THE ATOM | |
| Properties of Radium—Energy evolved by radium—Necessity for a disintegration theory—Disintegration theory—Constitution of the atom—Rutherford's atom—Scattering of alpha particles—Stopping power of substances | 32 |
| CHAPTER VI | |
| RADIO-ACTIVITY AND CHEMICAL THEORY | |
| Influence upon chemical theory—The periodic system—Basis of the periodic system—Influence of positive nucleus—Determination of the atomic number—Use of X-ray spectra—Changes caused by ray-emission—Atomic weight losses—Lead the end product—Changes of position in the periodic system—Changes from loss of beta particles—Isotopes—Radio-activity in nature—Radio-active products in the earth's crust—Presence in air and soil waters—Cosmical radio-activity | 41 |
| Index | 53 |
A BRIEF ACCOUNT OF
RADIO-ACTIVITY
A BRIEF ACCOUNT OF
RADIO-ACTIVITY
CHAPTER I
DISCOVERY OF RADIO-ACTIVITY
The object of this brief treatise is to give a simple account of the development of our knowledge of radio-activity and its bearing on chemical and physical science. Mathematical processes will be