Radioactive element

“ The supposition is that the helium is the product of the atomic decomposition of the radioactive gas. It may be argued that the experiments only prove that radium is not an element, but only a compound of staple elements. On the other hand, the production of this radioactive gas is not influenced by changes of temperature, which is true of no chemical process, and is accompanied by radioactivity, which is not a phenomenon of chemical changes. ”

“ Radioactive change originates in the atomic nucleus. The expulsion of an α-particle therefrom decreases the atomic weight by 4 units, necessitates (since the α-particle carries two positive charges) the removal of two electrons from the shell in order to maintain electrical neutrality, and hence changes the chemical nature of the body, transmuting the element into one occupying a position two places to the left in the periodic system (for example, the change of radium into niton) . But radioactivity sometimes results in the expulsion of a β-particle from the nucleus. ”

“ The work of the Curies in turn stimulated many studies of the effect of radioactivity. It was not long before experimenters learned that naturally radioactive elements—like radium—were also useful in cancer therapy. These elements emitted gamma rays, [2] which are like X rays but usually are even more penetrating, and their application often could be controlled better than X rays. Slowly, over the years, reliable methods were developed for treatment with these radioactive sources, and instruments were designed for measuring the quantity of radiation received by the patient. ”

“ There has been little or no proof obtained that any artificial transmutation of the elements is possible, but the spontaneous transformation of the radioactive elements brings forward the possibility that other elements are changing imperceptibly, and that a state of evolution exists among them. All of the radioactive changes that we know proceed from higher to lower atomic weights, and we are entirely ignorant of the process by which uranium and thorium must have been produced originally. ”

“ It is supposed that uranium breaks up in two distinct ways, the smaller fraction giving rise to actinium. The evidence, however, on this point, is not yet complete.
The radioactive elements are in some respects more interesting and important than stable elements, for, in addition to the ordinary physical and chemical properties, they possess the radioactive property which allows us to study the mode and rate of transformation of their atoms. ”

“ It is now well established, notably by the work of Elster and Geitel, that radioactive matter is widely distributed both in the earth's crust and atmosphere. There is undoubtedly evidence of the presence of the radium emanation in the atmosphere, in spring water, and in air sucked up through the soil. It still remains to be settled whether the observed radioactivity of the earth's crust is due entirely to slight traces of the known radioactive elements or to new kinds of radioactive matter. ”

“ It seems reasonable to suppose that while the radioactive substances behave chemically as elements, they are, in reality, compounds of simpler kinds of matter, held together by much stronger forces than those which exist between the components of ordinary molecular compounds. Apart from the property of radioactivity, the radio-elements do not show any chemical properties to distinguish them from the non-radioactive elements except their very high atomic weight. ”

“ When, however, we take into account the radioactive content of
the sediments the matter assumes a different aspect.
The facts as to the general distribution of radioactive
substances at the surface, and in rocks which have come from
considerable depths in the crust, lead us to regard as certain
the widespread existence of heat-producing radioactive elements
in the exterior crust of the Earth. We find, indeed, in this fact
an explanation—at least in part—of the outflow of heat
continually taking place at the surface as revealed by the rising
temperature inwards. ”

“ If the same experiment be repeated with a salt of radium it is found that the current of air produces only a feeble effect. With uranium and polonium, which do not emit the emanation, the current of air has no effect. On the contrary, in the case of actinium, the action of the current of air is to suppress four-fifths of the conductivity of the air. It may be concluded that for thorium, and especially for actinium, the radiation of the emanation is very important in comparison with the radiation of the radioactive substance itself. ”

“ Radioactivity is characterized by the kind of particle emitted from the nucleus (our examples, so far, have been of beta and gamma particles) , by the energy possessed by this particle, and by the half-life in which the radioactive decay takes place.
The biological hazard from radioactivity depends on all three of these characteristics. No matter whether the radioactive nuclei are produced in an atomic explosion or in an atomic reactor, some time will in general elapse before a human population can become exposed. ”

“ These facts are important because they determine the magnitude and the character of the danger when the radioactivity finally falls out of the cloud and is deposited on the surface of the earth. Those radioactive particles which disintegrate while still in the cloud need not worry us since this radiation can have no effect on living organisms that may be underneath. Provided that the cloud is more than a few hundred feet above the ground, the beta and gamma rays released in these disintegrations merely dissipate their energy in ionizing the air. ”

“ Induced Radioactivity.—Radium, thorium, and actinium have the property of acting externally, apart from the Becquerel rays that they emit. They communicate little by little their radioactive properties to substances in their neighborhood, and the latter emit in turn Becquerel rays. The activity can be transmitted to gases, liquids, and solids. The phenomenon is known as induced radioactivity.
Induced radioactivity propagates itself in gases step by step by a sort of conduction, and is not at all due to direct radiation from the body which causes it. ”

“ Particularly significant studies have been conducted of the absorption of radionuclides by plants and animals living on nearby reefs and islands, and of both lateral and vertical diffusion rates of elements in the open ocean. [8]
The 1954 nuclear test at Eniwetok Atoll produced heavier-than-expected local radioactive fallout. Since then, both 24 American and Japanese scientists have studied water-mass movement rates, using the fallout radionuclides strontium-90 and cesium-137 themselves as tracer elements. ”

“ Fallout radioactivity is assessed as a potential specific hazard to human populations.
2. Conditions created by fallout are examined for their potential long-term ecological significance.
3. Radionuclides introduced into the environment by nuclear tests, reactor operations, or other means are used as trace materials in basic studies in biological systems.
4. Radioactive forms of minerals and nutrients are deliberately introduced into biosystems—in measured amounts and under conditions of control—for studies of metabolic cycles and rates of flow of energy and nutrition. ”

“ Life on earth evolved amid constant exposure to ionizing [3] radiation, from the earth itself and from space, known as 4 background radiation. Therefore environmental studies must be conducted in relation to, and with understanding of, background radioactivity.
This Pacific Ocean coconut crab, member of a family that usually sticks to tide-covered beaches, depends on coconut trees for its food.
Of some 340 kinds of atoms that have been found in nature, about 70 are radioactive. ”

“ After the storage period, the gas is pumped into an array of instruments known as a low-background PROPORTIONAL COUNTER, and its radioactivity is determined. This is an involved process. First there is the matter of the BACKGROUND COUNT.
The background count of an instrument is the number of pulses (counts) it will give per unit time when there is no radioactive sample in it. These counts are caused by cosmic rays, by radioactive contamination always found in the vicinity of the counter, or by any contamination inside the instrument. ”

“ This property of nuclei to decay by themselves is called radioactivity. Radioactive nuclei decay at constant rates regardless of temperature, pressure, chemical combination, or physical state. The process goes on no matter what happens to the atom. In other words, the activity inside the nucleus is in no way affected by what happens to the ELECTRONS circling around it. (Only in very special cases can outside disturbances affect the radioactivity of a nucleus and then only slightly. For all practical purposes, rates of radioactive decay are constant.) ”

“ It is not improbable that a close examination of the radioactivity of the different soils may lead to the discovery of radioactive substances which are not found in pitchblende or other radioactive minerals. ”

“ Nuclear tests, although not the only sources of man-made radioactivity, have been until now the most significant ones and the only sources touching large areas of the earth. The total product of nuclear testing is small in relation to the natural burden of radioactivity, raising the level of radiation to which all life is subject by a factor of one-tenth or less. But it is the unknown element, the degree to which fallout radioactivity may introduce new influences into the environment, that gives concern. ”

“ The lead-210 will then decay with its 22-year half-life.”
The radioactive series that starts with uranium is like a series of lakes connected by waterfalls. As long as uranium, the big one on top, has water in it, the others will be full and the falls will keep flowing. ”

“ A reactor accident conceivably could add a unique hazard since neutron radiation might change the normally stable, nonradioactive atoms in the bodies of nearby workers into radioactive ones. Even gold or silver fillings in their teeth might become radioactive. ”

“ Most radioactive isotopes in use today, however, are prepared artificially by nuclear reactions. When a high-energy particle, such as a proton, a deuteron, an alpha particle, or a neutron, collides with an atom, a reaction takes place, leading to the formation of a new, unstable compound—a man-made radioactive isotope. ”

“ The interior of a house or building should be quite safe from any outside source of charged particles emitted by radioactive substances except possibly the most energetic beta rays. Only if the source of charged particles is inside the body so that in spite of their limited ranges the particles can find their way to sensitive tissues, is there any danger. ”

“ The chemical individuality of radium remains almost entirely unknown; nevertheless it is constantly sought, especially in those regions where pitchblende deposits occur, and where they already dream of developing radium ores and a future radium industry. So far as known, the occurrence of radioactive substances is tied to that of uranium. This is in the highest degree surprising and can not be understood if we are to assume the presence of special elements. ”

“ Of the 200 million electron-volts released in fission, about 10 million go into gamma rays and neutrons created in the fission process itself. This energy contributes to the immediate and local radiation danger. Another 24 million electron-volts go into radioactivity of the fission products, and of this, about half go into neutrinos, which are neither dangerous nor useful; the other half is carried by electrons and gives rise to the delayed radioactive hazard. But the bulk of the energy, over 160 million electron-volts, goes into kinetic energy of the two primary fission fragments. ”

“ These veins are veins of pitchblende which are found hardly anywhere in Europe except in the north of Bohemia and which are worked near the little town of Joachimsthal. And those radioactive bodies are uranium, thorium, helium and chiefly, in the case which we are considering . . ."
"Radium," François interrupted.
"You've said it, my boy: radium. Phenomena of radioactivity occur more or less everywhere; and we may say that they are manifested throughout nature, as in the healing action of thermal springs. But plainly radioactive bodies like radium possess more definite properties. ”

“ The reason mankind had remained unaware of radioactivity and very aware of chemical reactions was, first, that the most common radioactive processes are so slow that their great energies were stretched over such enormous blocks of time as to be insignificant on a per second basis. ”

“ The impact of the α rays on matter sets free a number of slow moving electrons which are very easily deflected by a magnetic or electric field. This type of radiation was first observed by J. J. Thomson, and has been called by him the δ rays.
Emanations or Radioactive Gases.—In addition to their power of emitting penetrating radiations, the substances thorium, actinium and radium possess another very striking and important property. Rutherford (15) in 1900 showed that thorium compounds (especially the oxide) continuously emitted a radioactive emanation or gas. ”

“ Almost 90% of 112 nests built by the yellow-legged mud-dauber species were radioactive, and the mud was delivering to the wasp eggs each hour a dose of penetrating radiation equal to that received by a man from all natural sources over a period of many years. ”