• WordNet 3.6
    • n radium an intensely radioactive metallic element that occurs in minute amounts in uranium ores
    • ***
Webster's Revised Unabridged Dictionary
  • Interesting fact: Marie Curie, the Nobel prize winning scientist who discovered radium, died of radiation poisoning
    • n Radium rā"dĭ*ŭm (Chem) An intensely radioactive metallic element found (combined) in minute quantities in pitchblende, and various other uranium minerals. Symbol, Ra; atomic weight, 226.4. Radium was discovered by M. and Mme. Curie, of Paris, who in 1902 separated compounds of it by a tedious process from pitchblende. Its compounds color flames carmine and give a characteristic spectrum. It is divalent, resembling barium chemically. The main isotope of radium found in pitchblende, radium-226, has a half-life of 1620 years, decaying first by alpha emission to radon.Radium preparations are remarkable for maintaining themselves at a higher temperature than their surroundings, and for their radiations, which are of three kinds: alpha rays beta rays, and gamma rayssee these terms). The beta and gamma rays seen in radium preparations are in fact due to disintegration of decay products of radium rather than the radium itself. By reason of these rays they ionize gases, affect photographic plates, cause sores on the skin, and produce many other striking effects. Their degree of activity depends on the proportion of radium present, but not on its state of chemical combination or on external conditions. The radioactivity of radium is therefore an atomic property, and is due to an inherent instability of the atomic nucleus which causes its decay in a process whose rate is first order. The disintegration of the radium nucleus is only the first in a series of nuclear disintegrations leading to production of a series of elements and isotopes. The chain has at least seven stages; the successive main products have been studied and are radon, a gaseous radioactive element belonging chemically to the inert noble gas series (originally called radium emanation or exradio radium A radium B radium C, etc. The successive products are unstable isotopes of several different elements, each with an atomic weight a little lower than its predecessor. Lead is the stable end product. At the same time, the light gas helium is formed, being generated when the expelled alpha particles (positively charged helium nuclei) acquire electrons. Radium, in turn, is formed in the pitchblende ore by a slow disintegration of uranium. Natural radium and also an isotope (radium-228, also called mesothorium I) formed by the decay of thorium, were at one time used to make a luminous paint for watch dials, until the danger of the radioactivity became fully appreciated, and use of such material in watches was discontinued. See also mesothorium.
    • ***
Century Dictionary and Cyclopedia
    • n radium A chemical element of very remarkable character, discovered in 1898 by Mme. Sklodowska Curie, working with her husband and M. Bémont. The element itself has not been isolated, and many writers incorrectly use the name radium when in reality a salt of the element, generally the chlorid or bromide, is meant. In following up the researches of Becquerel on the radioactivity of uranium and its compounds, Mme. Curie found that certain ores of uranium manifest this activity to a greater extent than can be accounted for by the uranium they contain. By patient and laborious examination of the constituents of pitchblende, a mineral containing a high proportion of uranium, she was able to separate a substance exhibiting radioactive properties greatly superior to those of uranium. This substance was found associated with the barium salts removed from the pitchblende and resembled barium so closely in its chemical properties that a separation of the two elements could be effected only by the repeated fractional recrystallization of the mixed chloride, the radium chlorid becoming more concentrated in the less soluble portion. On further investigation it was found that the radium, present only in minute proportion in pitchblende, was retained and somewhat concentrated in certain residues obtained from pitchblende in the commercial extraction of uranium at the works in connection with the mines at Joachimsthal in Austria. These residues had accumulated for years under the supposition that they were valueless and a considerable quantity was placed at the disposal of M. and Mme. Curie for the continuation of their researches. The residues consist chiefly of the sulphates of lead and calcium together with the oxids of silicon, aluminium, and iron. They also contain greater or less quantities of nearly all the metals (copper, bismuth, zinc, cobalt, manganese, nickel, vanadium, antimony, thallium, the rare earths, niobium, tantalum, arsenic, barium, etc.). They were subjected to suitable chemical treatment by which the barium and radium were removed and obtained in the form of a mixed chlorid. The radium and barium chlorids were then separated from one another by fractional crystallization repeated many hundreds of times, and a pure chlorid of radium was obtained. In this way the Curies separated about one gram of fairly pure radium chlorid from eight tons of residues, representing nearly eighty tons of the original ore. Giesel has slightly modified the process, conducting the recrystallization with the bromides instead of the chlorids, which considerably facilitates the isolation of a pure radium salt. Pure radium chlorid or bromide resembles common salt in general appearance when freshly prepared, but quickly acquires a yellowish or brownish color. It gives a fine carmine-red color to flame, and affords characteristic flame and spark spectra. It is visibly luminous in a dark room. Radium belongs to the class of the alkaline-earth metals, calcium, strontium, and barium, and its compounds in general resemble theirs. Its atomic weight, as first determined by Mme. Curie, was 225 (O = 16); later she obtained the figures 226.5. The element occupies, in the periodical classification, the same position in the twelfth of Mendeléjeff's series as Ca, Sr, and Ba do in the fourth, sixth, and eighth. Its radioactivity is about one million times greater than that of uranium. It produces phosphorescent luminosity in the diamond, kunzite, and various other minerals, and on screens coated with barium platinocyanide, crystalline zinc sulphid, etc. Radium salts give off α-, β-, and γ-rays (see radioactivity). The nature of the α-particles has been closely investigated by Rutherford, who has shown that they are of atomic dimensions, have a mass equal to that of helium atoms, and are therefore in all probability the source of the helium continuously evolved b, radium salts as demonstrated in the experiments of Ramsay and Soddy. In addition to helium, a radium salt produces also a highly radioactive gaseous substance known as the radium emanation, which accumulates in the solid salt and escapes when this is heated or dissolved in water. This emanation is a gas of the argon family, autoluminescent and giving a characteristic bright-line spectrum. It has an atomic weight (as determined from the diffusion rate and assuming the molecule to be monatomic) differing but little from that of radium and is condensed at a temperature of from—150 to—155° C. It gradually loses its radioactivity and is transformed, at a rate corresponding to a change of one half the amount present in 3.8 days, into a series of successive, rapidly-changing, solid, radioactive products known as radium A, radium B, and radium C, which are deposited on the surface of any object in contact with the emanation and impart to this a temporary radioactivity. The continuous production of the emanation in radium salts is wholly independent of the chemical character of the salt and is directly proportional to the amount of radium contained in it. It has also been observed that radium salts evolve heat at the surprising rate of about 118 calories per hour for each gram of radium which they contain and are thus enabled under favorable conditions to maintain their temperature considerably above that of their surroundings. These and other considerations have led to the explanation of the behavior of radium and other radioactive elements by the so-called disintegration theory, first proposed by Rutherford and Soddy. According to this theory the radium atoms are unstable systems and a certain proportion of the total number present are constantly undergoing disintegration, being transformed into atoms of other elements having distinctive physical and chemical properties. Thus an atom of radium breaks up, expelling an α-particle constituting an atom of helium, and produces an atom of the gaseous emanation, the latter undergoing subsequent transformation into an atom of radium A, etc. The energy appearing in the course of these changes is assumed to be inherent in the original atom and to manifest itself only when this is altered or destroyed. On this assumption the behavior of radioactive substances is in no way contradictory to the doctrine of the conservation of energy. On the basis of this theory it is obvious that in any given quantity of a radium salt in the course of time the amount of radium present must gradually decrease, and it has been experimentally demonstrated that the time required for exactly one half of the radium to disappear would be about 2000 years. It can be shown that at this rate of disintegration the earth, if composed initially of pure radium, would, after the lapse of 100,000 years, contain a smaller proportion of radium than is now present in the common rocks and soil which constitute its surface. Since the age of the earth is certainly greater than 100,000 years, it is evident that the radium now in existence must have been renewed or formed in some manner. The origin of radium has therefore been the subject of careful investigation and the conclusion has been reached that radium is formed through the atomic disintegration of another radioactive element, uranium, which is much more abundant, and is widely distributed. Radium has been found present in the natural mineral substances containing uranium in a constant and unvarying proportion, three parts by weight of radium occurring associated with every one hundred million parts of uranium. It has been found that radium is not formed directly from uranium, and it has been shown by Boltwood that another radio-element, ionium, is first produced by the disintegration of the uranium atoms which after further change are converted into radium atoms. A continuation of the atomic transformation results in the successive production of a further series of radio-elements or products: radium emanation, radium A, radium B, radium C, radium D (radiolead), radium E, radium F, and radium G (polonium). As no further radioactive products have been detected in this series it is presumed that after radium G an unchanging, stable form of matter is attained. Although the evidence as to the nature of this final product is indirect and not wholly conclusive, there is reason for believing that it is ordinary lead. Radium has been found widely distributed in minute proportions in the rocks and minerals of the globe, in soils, in the waters of thermal springs, in sea-water, and in marine deposits. The chief source of the radium salts which nave been prepared has been almost entirely the pitchblende residues from the Austrian factories, and owing to the comparative rarity of this material and the laborious and costly methods of treatment necessary for its extraction, radium salts have commanded extraordinarily high prices, being frequently sold in small quantities at a rate exceeding $150,000 per gram of radium. The radiation from radium salts, especially the β- and γ-rays, reduces sensitive silver salts and produces an image upon a photographic plate screened by black paper. It also brings about other chemical changes, converting oxygen into ozone and ordinary phosphorus into red phosphorus, and causing the decomposition of water (with an excess of hydrogen over oxygen in the gaseous product as collected). It produces darkening of color in diamonds, quartz, mica, and especially glass, some specimens of glass becoming brown and others, more commonly, acquiring a violet or purple tinge. Various other substances become more or less colored. Radium salts, even at some little distance from the human skin, produce reddening in a few hours, and after days give rise to painful sores, difficult to heal. They have been used with some degree of success in the treatment of lupus and other forms of disease of the superficial tissues. They exert a marked germicidal action on various micro-organisms.
    • ***
Chambers's Twentieth Century Dictionary
    • Radium a rare element whose radiations act upon photographic plates and have properties like the X-rays
    • ***


Webster's Revised Unabridged Dictionary
NL., fr. L. radius, ray


In literature:

No matter how much Caron of Mars would like to get his claws on this radium.
"A World is Born" by Leigh Douglass Brackett
Radium, 184, 185, 187, 188.
"Electricity for Boys" by J. S. Zerbe
Young Comte now proved his humanity by accusing his teacher of stealing his radium.
"Little Journeys to the Homes of the Great Philosophers, Volume 8" by Elbert Hubbard
It's sort of like radium, and half a pint of the distilled drug would be worth over twenty-five thousand dollars.
"The Heart of Unaga" by Ridgwell Cullum
It is radium we have to have to make the return trip.
"Operation Earthworm" by Joe Archibald
Looting young worlds of the precious radium ores!
"Raiders of the Universes" by Donald Wandrei
I have some knowledge of radium ores.
"Astounding Stories of Super-Science April 1930" by Various
At his side hung a long-sword, a short-sword, a dagger, and one of the destructive radium revolvers that are common upon Mars.
"The Gods of Mars" by Edgar Rice Burroughs
I need not say that all are in gold; but a few special sets in radium can be obtained.
"Punch or the London Charivari, Vol. 147, December 23, 1914" by Various
A semi-government trust, which controlled virtually the entire Earth supply of radium.
"Astounding Stories of Super-Science, March 1930" by Various

In news:

Jackson's "Radium Mine," painted in 1938, is to be sold Nov 22 at the Heffel Fine Art fall auction of Canadian art.
'Fracking' brine Gas-well waste full of radium.
Radium Girls' begins Nov 1: Tells story of real labor movement of the 1920s.
Singing a Joyful Noise at Radium Springs Middle.
'Fracking' brine Gas-well waste full of radium .
Radium was hot at the turn of the twentieth century.
Exploring science fiction's ' Radium Age'.
New USGS report finds levels of radium detected exceed EPA drinking water standards.
Stacy City Engineer Chuck Schwartz has been wrestling with an affordable solution to the issue of radium in the Stacy drinking water.
Radium Middle lockers may get upgrade.
An ongoing issue with Radium Springs Middle School lockers may be be addressed soon.
Stripmall Architecture's " Radium Girls".
Megatrax Announces Partnership with Radium Sound.
Put Radium Test Results On Consumers' Water Bills.
Singing a Joyful Noise at Radium Springs Middle.

In science:

The radiation from radium revealed a previously unknown source of energy.
How the sun shines
Moreover, over the years both theoretical and experimental researches have paid attention to the effort—researchers at KVI may attempt a similar experiment in singly ionized radium.
Single barium ion spectroscopy: light shifts, hyperfine structure, and progress on an optical frequency standard and atomic parity violation
Radium-Excited Activity I” from the decay of radium emanation earlier [103].
Discovery of the thallium, lead, bismuth, and polonium isotopes
The element radium was discovered in 1898 by P.
Discovery of the astatine, radon, francium, and radium isotopes
Fig. 5: Radium isotopes as a function of time when they were discovered.
Discovery of the astatine, radon, francium, and radium isotopes