Radium decomposition

It is now accepted as a proved fact that the element radium decomposes with the formation of other elements, the simplest of which is apparently helium, and the experiments of Sir William Ramsay have indicated that the energy liberated by radium can effect the transmutation of other elements into one another but in such cases man can only watch the changes that go on, and cannot control or vary them. But in the building-up process that has apparently now been discovered, the energy for the change is artificially supplied and controlled, and the changes are thus of a different order from the radioactive decompositions of a decaying element. 

Radium F is thought to be identical with Polonium ( 87). Another product is also obtained by these decompositions, with which we shall deal later (94). 

Uranium and thorium differ in one important respect from radium, inasmuch as the first product of the decomposition of the uranium and thorium atoms is in both cases solid. Sir... 

It had been observed already that the radioactive minerals on heating give off Helium — a gaseous element, characterised by a particular yellow line in its spectium — and it seemed not unlikely that helium might be the ultimate decomposition product of the emanation. A research to settle this point was undertaken by Sir William Ramsay and Mr. Soddy, and a preliminary experiment having confirmed the above speculation, they carried out further very careful experiments. "The maximum amount of the emanation obtained from 50 milligrams of radium bromide was conveyed by means of oxygen into a U-tube cooled in liquid air, and the latter was then extracted by the pump." The spectrum... 

Here, then, for the first time in the history of Chemistry, we have the undoubted formation of one chemical element from another, for, leaving out of the question the nature of the emanation, there can be no doubt that radium is a chemical element. This is a point which must be insisted upon, for it has been suggested that radium may be a compound of helium with some unknown element or, perhaps, a compound ofhdium with lead, since it has been shown that lead is probably one of the end products of the decomposition of radium. The following considerations, however, show this view to be altogether untenable (i.) All attempts to prepare compounds of helium with other... 

Potassium iodide is coloured sky-blue when heated in a sealed tube with the vapours of potassium or sodium. The salt is also coloured by cathode rays.41 The decomposition of soln. of the alkali iodides by exposure to radium radiations, and ultra-violet light increases with increasing cone. A. Kailan supposed the radiations decompose the undissociated iodide liberating iodine and hydrogen both in acid and in alkaline soln. Aq. soln. of the alkali iodides are neutral, but, as 0. Loew 42 has shown, the soln. gradually acquires a yellow colour and an alkaline reaction when kept for say 8 to 10 days if air be excluded, the soln. remained colourless for 4 months. A. Houzeau attributed the effect to the presence of traces... 

RADIUM. [CAS 7440-14-41, Chemical element symbol Ra, at. no. 88, at. wt. 226.025, periodic table group 2 (alkaline earths), mp 700VC, bp 1,140°C, density 5 g/cm3 (20°C). Radium metal is white, rapidly oxidized in air, decomposes H O, and evolves heat continuously at the rate of approximately 0.132 calorie per hour per mg when the decomposition products are retained, and the temperature of radium salts remains about 1,5°C above the surrounding environment. Radium is formed by radioactive transformation of uranium, about 3 million parts of uranium being accompanied in nature by 1 part radium. Radium spontaneously generates radon gas at approximately the rate of 100 mmJ per day per gram of radium, at standard conditions, Radium usually is handled as the chloride or bromide, either as solid or in solution. The radioactivity of the material... 

Uranium is a while metal, ductile, malleable, and capable of taking a high polish, but tarnishes readily on exposure to the atmosphere. Finely divided uranium burns upon exposure to air, and the compact metal burns when heated in air at 170 0 Uranium metal slowly decomposes water at ordinary temperatures and rapidly at 100 0 is soluble in HC1 and in HN03 and is nnattacked by alkalis. Chemically related to chromium, molybdenum, and tungsten and, like thorium, is radioactive. In the radioactive decomposition radium is formed. Discovered by Klaproth in 1789. 

Alpha decay is nuclear decomposition such that one of the products of the reaction is an alpha (a) particle, 4He. In an example of alpha decay, radium-222 decomposes to form radon-218 plus an alpha particle ... 

Consider, for example, the decomposition of radium into helium and radon. It is found that about one radium atom in two thousand decomposes in a year. Suppose we are asked to predict the state of a particular radium atom at some future time, say after ten years. All we can say is that it will either be unchanged or will have decomposed, and that the chance of... 

Although not strictly a case of catalysis, the effect of radium radiation on the rate of decomposition of hydrogen peroxide is most conveniently mentioned here the penetrating rays are the most effective.9... 

Up till a few years ago four elements were still missing from the roll-call, in fact 43, 61, 85, and 87, although their discovery had been announced repeatedly but always incorrectly. These elements have now all been prepared artificially and they have been found to be radioactive, while there are also grounds for assuming that stable isotopes of these elements cannot exist. These elements, if they have ever existed, have, at least as far as the first two are concerned, very probably died out on earth long ago, just as radium (half-life 1590 years) would also have remained unknown to us if it had not continually originated afresh from the extremely slowly decaying uranium (half-life 4.49 io9 years). The presence of 87 in extremely small quantities in the decomposition products of actinium was first dis-... 

SAFETY PROFILE Suspected carcinogen. Severe radiotoxicity. Very dangerous to handle. Radiation Hazard Namral isotope 2ioPo (radium-F, uranium series), To.s = 138 days. Decays to stable by alphas of 5.3 MeV. When heated to decomposition it emits toxic and radioactive fumes of Po. See also PLUTONIUM. 

Early experiments in liquids were quite variable for many reasons. The conductivity technique, which was used in the gas phase to measure dose, was not applicable to the liquid phase. Reactions were measured using dissolved radium salts or radon gas as the ionization source. Some thought the chemistry was due to the reactions with radium however, it was soon recognized that it was the emitted rays that caused the decomposition. Both radium and radon could cause radiation damage. Because the radon would be partitioned between the gas and liquid phase, the amount of energy that was deposited in the liquid depended critically on the experimental conditions such as the pressure and amount of headspace above the liquid. In addition, because the sources were weak, long irradiation times were necessary and products, such as hydrogen peroxide, could decompose. 

It is interesting to point out that in a disintegration chain of radioactive elements in a steady state all of the radioactive elements are present in the same radioactive amounts. For example, let us consider one gram of the element radium, in a steady state with the first product of its decomposition, radon nd the successive products of dis-... 

The amount of radon present in a steady state with one gram of radium can be calculated by consideration of the first-order reaction-rate equations discussed in Chapter 19. The reaction-rate constant for the decomposition of radium is inversely proportional to its half-life. Hence when a steady state exists, and the number of radium atoms undergoing decomposition is equal to the number of radon atoms undergoing decomposition, the ratio of the numbers of radon atoms and radium atoms present must be equal to the ratio of their half-lives. 

The significance of the uranium reactors as a source of radioactive material can be made clear by a comparison with the supply of radium now in use. About 1000 curies (1000 grams) of radium has been separated from its ores and put into use, mainly for medical treatment. The rate of operation mentioned above for the reactors at Hanford represents the fission of about 5 X 10- nuclei per second, forming about 10 X 10 radioactive atoms. The concentration of these radio-acti e atoms will build up until they are undergoing decomposition at tjie rate at which they, are being formed. Since 1 curie corresponds to 3.71 X 10 disintegrating atoms per second, these reactors develop a radioactivity of approximately 3 X 10 curies that is, about thirty million times the radioactivity of all the radium which has been so far isolated from its ores. 

Gamer and Moon [34] reported effects of radiation other than color changes the effects produced by the emission from radium on barium azide were dependent on temperature and led to the acceleration in the thermal decomposition. On the other hand the thermal decomposition of mercury ftilmi-nate was not affected in the same environment. 

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