Radium

There are many isotopes of Radium from g Ra to gg Ra but the one with the longest half-life is gg Ra with a half-life of 1599 years and decays by emitting an alpha particle (He ) with an energy of 4.870 million electron volts (MeV). 

we see as a laboratory source of alpha particles the supply would be pretty constant over a long period of time. Another consideration is that radium is in the same column of the periodic chart as Ca and so biologically it might have similar chemistry to Ca and become trapped in bone tissue where it would be radioactive for a long time. Thus, this interlude regarding the fact that first-order decay is a useful model for nuclear processes has provided an opportunity to discuss some aspects of nuclear chemistry. Considering the crossover of physics and chemistry in the work of the Curies (Marie, Pierre, and Irene) and information in the popular domain regarding nuclear chemistry, we think this brief discussion is justified as an essential part of physical chemistry. 

ATOMIC MASS 226.03 amu VALENCE 2 OXIDATION STATE +2 NATURAL STATE  

ORIGIN OF NAME Radium s name is derived from the Latin word radius, which means ray.  

ISOTOPES There are no stable isotopes of radium. Radium has 25 known radioisotopes, ranging from Ra-206 to Ra-230. Their half-lives range from a fraction of a second to hundreds of years. Radium-226 was discovered by the Curies and has a half-life of about 1630 years. Ra-226 is the most abundant isotope, and thus, Ra-226 is used to determine radium s atomic mass. 

Various radium isotopes are derived through a series of radioactive decay processes. For example, Ra-223 is derived from the decay of actinium. Ra-228 and Ra-224 are the result of the series of thorium decays, and Ra-226 is a result of the decay of the uranium series. 

Energy Levels/Shells/Electrons Orbitals/Electrons 

TOOOl 3M Company, 3M Empore Extraction Disk T0014 Advanced Recovery Systems, Inc., DeCaF 

T0062 Argonne National Laboratory, Ceramicrete Stabilization Technology T0088 Battelle Pacific Northwest National Laboratory, Terra-VIT Vitrification Technology T0132 Brookhaven National Laboratory, Biochemical Recovery of Radionuclides and Heavy Metals 

T0151 Ceramic Immobilization of Radioactive Wastes—General T0178 Constructed Wetlands—General 

T0179 Constructed Wetlands for Acid Mine Drainage—General 

T0192 CURE International, Inc., CURE Electrocoagulation Wastewater Treatment System 

Choppin, Gregory R. Liljenzin, Jan-Olov and Rydberg, Jan (2001). Radiochemistry and Nuclear Chemistry, 3rd edition. Woburn, MA Butterworth-Heinemann. 

Ehmann, William D., and Vance, Diane E. (1991). Radiochemistry and Nuclear Methods of Analysis. New York Wiley. 

Eriedlander, Gerhart, et al. (1981). Nuclear and Radiochemistry, 3rd edition. New York Wiley. 

Radium is the last of the alkafine earth metals comprising the second column of the Periodic Table. While there are twenty-five known isotopes of radium (only four of which are found naturally), all of them are radioactive. Of these isotopes, radium-226 is the most common, with a half-fife of about 1,600 years. 

Radium was first isolated in 1898 by Marie Sklodowska Curie and her husband, Pierre Curie. They were studying the radioactivity of pitchblende, a uranium-rich ore, and noticed that the ore was still radioactive with all the uranium removed. After years of painstaking work, the Curies eventually isolated radium and named it for the Latin word radius, meaning ray. For this work, Madame Curie was awarded the Nobel Prize in Chemistry in 1911, her second such honor (the first one, in physics, shared with her husband and Henri Becquerel in 1903 for their initial studies of radioactivity). 

When the Curies and G. Bemont analysed pitchblende they noticed a higher radioactivity of one more fraction, apart from the bismuth fraction. After they had succeeded in extracting polonium they started to analyse the second fraction thinking that they could find yet another unknown radioactive element. 

The new element was named radium from the Latin radius meaning ray. The birthday of radium was December 26,1898. when the members of the Paris Academy of Sciences heard a report entitled On a new highly radioactive substance contained in pitchblende . The authors reported that they had managed to extract from the uranium ore tailings a substance containing a new element whose properties are very similar to those of barium. The amount of radium contained in barium chloride proved to be sufficient for recording its spectrum. This was done by the well-known French spectral analyst E. Demarcay who found a new line in the spectrum of the extracted substance. Thus, two methods—radiometry and spectroscopy—almost simultaneously substantiated the existence of a new radioactive element. 

The discovery of radium was the best substantiated one among the many alleged discoveries of radioactive elements, which soon followed. Every year more new discoveries were reported. Radium was also the first radioactive element obtained in the metallic form. 

Marie Curie and her collaborator A. Debieme electrolyzed a solution containing 0.106 g of radium chloride. Metallic radium deposited on the mercury cathode forming amalgam. The amalgam was put into an iron vessel and heated under a hydrogen flow to remove mercury. Then grains of silvery whitish metal glistened at the bottom of the vessel. 

The discovery of radium was one of the major triumphs of science. The studies of radium contributed to fundamental changes in our knowledge of the properties and structure of matter and gave rise to the concept of atomic energy. Finally, radium was also the first radioactive element to be practically used (for instance, in medicine). 

In June 1903 Marie Curie was awarded her doctorate. In December she, Pierre, and Becquerel shared the Nobel Prize in physics for their study of radioactivity. 

A photograph of 2.7 g of radium bromide, taken by its own light on October 15, 1922. (From R. Wolke Marie Curie s Doctoral Thesis Prelude to a Nobel Prize. Chem Educ., 65(7) 561 (1988). Published with permission of Archives Pierre et Marie Curie, Paris.) 

In 1911, Marie received the Nobel Prize in chemistry for her isolation of radium and polonium. 

In those days no one knew just how dangerous radioactivity was. Radium is an extremely powerful alpha emitter, as represented in Equation (13.6)  

Carell and Olin (1961b) also determined a value for the stability constant of BaOH in 3 moll NaClO at 25°C. For the same reasons as given for SrOH, the value has been retained, but the uncertainty in the value has been increased to 0.2 log units. 

The thermodynamic data for Ba(s) and Ba are taken from Grenthe et al. (1992). The data are listed in Table 7.25. The thermodynamic data listed in Table 7.23 have been derived utilising these values. 

Radium has the largest ionic radius (1.43 A (Shannon and Prewitt, 1969)) and, consequently, has the weakest hydrolytic reactions. As a result of the weak reactions, the stabilities are difficult to measure. Adding to this difficulty is the radioactive nature of radium, with studies needing in many cases to be conducted only using specialised equipment. It is considered that radium will provide the main contribution to the long-term risk, in relation to radiation dose, in the case of the failure of a nuclear waste repository (SKB, 2006). Thus, its reactions in water, including hydrolysis, are quite important. 

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The white solid oxides MjO and M 0 are formed by direct union of the elements. The oxides MjO and the oxides M"0 of calcium down to radium have ionic lattices and are all highly basic they react exothermically with water to give the hydroxides, with acids to give salts, and with carbon dioxide to give carbonates. For example... 

The elements in Group II of the Periodic Table (alkaline earth metals) are. in alphabetical order, barium (Ba). beryllium (Be), calcium (Ca). magnesium (Mg), radium (Ra) and strontium (Sr). 

Poland, native country of Mme. Curie) Polonium, also called Radium F, was the first element discovered by Mme. Curie in 1898 while seeking the cause of radioactivity of pitchblend from Joachimsthal, Bohemia. The electroscope showed it separating with bismuth. 

Polonium is a very rare natural element. Uranium ores contain only about 100 micrograms of the element per ton. Its abundance is only about 0.2% of that of radium. 

Polonium-210 is a low-melting, fairly volatile metal, 50% of which is vaporized in air in 45 hours at 55C. It is an alpha emitter with a half-life of 138.39 days. A milligram emits as many alpha particles as 5 g of radium. 

From radium called niton at first, L. nitens, shining) The element was discovered in 1900 by Dorn, who called it radium emanation. In 1908 Ramsay and Gray, who named it niton, isolated the element and determined its density, finding it to be the heaviest known gas. It is essentially inert and occupies the last place in the zero group of gases in the Periodic Table. Since 1923, it has been called radon. 

Twenty isotopes are known. Radon-22, from radium, has a half-life of 3.823 days and is an alpha emitter Radon-220, emanating naturally from thorium and called thoron, has a half-life of 55.6 s and is also an alpha emitter. Radon-219 emanates from actinium and is called actinon. It has a half-life of 3.96 s and is also an alpha emitter. It is estimated that every square mile of soil to a depth of 6 inches contains about 1 g of radium, which releases radon in tiny amounts into the atmosphere. Radon is present in some spring waters, such as those at Hot Springs, Arkansas. 

Radon is still produced for therapeutic use by a few hospitals by pumping it from a radium source and sealing it in minute tubes, called seeds or needles, for application to patient. This... 

Care must be taken in handling radon, as with other radioactive materials. The main hazard is from inhalation of the element and its solid daughters which are collected on dust in the air. Good ventilation should be provided where radium, thorium, or actinium is stored to prevent build-up of the element. Radon build-up is a health consideration in uranium mines. Recently radon build-up in homes has been a concern. Many deaths from lung cancer are caused by radon exposure. In the U.S. it is recommended that remedial action be taken if the air in homes exceeds 4 pCi/1. 

L. radius, ray) Radium was discovered in 1898 by Mme. Curie in the pitchblende or uraninite of North Bohemia, where it occurs. There is about 1 g of radium in 7 tons of pitchblende. The element was isolated in 1911 by Mme. Curie and Debierne by the electrolysis of a solution of pure radium chloride, employing a mercury cathode on distillation in an atmosphere of hydrogen this amalgam yielded the pure metal. 

Originally, radium was obtained from the rich pitchblende ore found in Joachimsthal, Bohemia. The carnotite sands of Colorado furnish some radium, but richer ores are found in the Republic of Zaire and the Great Lake region of Canada. Radium is present in all uranium minerals, and could be extracted, if desired, from the extensive wastes of uranium processing. Large uranium deposits are located in Ontario, New Mexico, Utah, Australia, and elsewhere. 

Inhalation, injection, or body exposure to radium can cause cancer and other body disorders. The maximum permissible border in the total body for 226Ra is 7400 becquerel. 

Gr. aktis, aktinos, beam or ray). Discovered by Andre Debierne in 1899 and independently by F. Giesel in 1902. Occurs naturally in association with uranium minerals. Actinium-227, a decay product of uranium-235, is a beta emitter with a 21.6-year half-life. Its principal decay products are thorium-227 (18.5-day half-life), radium-223 (11.4-day half-life), and a number of short-lived products including radon, bismuth, polonium, and lead isotopes. In equilibrium with its decay products, it is a powerful source of alpha rays. Actinium metal has been prepared by the reduction of actinium fluoride with lithium vapor at about 1100 to 1300-degrees G. The chemical behavior of actinium is similar to that of the rare earths, particularly lanthanum. Purified actinium comes into equilibrium with its decay products at the end of 185 days, and then decays according to its 21.6-year half-life. It is about 150 times as active as radium, making it of value in the production of neutrons. 

Radon-222 [14859-67-7] Rn, is a naturally occuriing, iaert, radioactive gas formed from the decay of radium-226 [13982-63-3] Ra. Because Ra is a ubiquitous, water-soluble component of the earth s cmst, its daughter product, Rn, is found everywhere. A major health concern is radon s radioactive decay products. Radon has a half-life of 4 days, decayiag to polonium-218 [15422-74-9] Po, with the emission of an a particle. It is Po, an a-emitter having a half-life of 3 min, and polonium-214 [15735-67-8] Po, an a-emitter having a half-life of 1.6 x lO " s, that are of most concern. Polonium-218 decays to lead-214 [15067-28A] a p-emitter haviag = 27 min, which decays to bismuth-214 [14733-03-0], a p-emitter haviag... 

Radon-220 [22481 8-7], Rn, a decay product of thorium, was discovered by Owens and Rutherford in 1900. The more common radon-222, a decay product of radium, was discovered later in the same year and was isolated in 1902. 

Argon-40 [7440-37-1] is created by the decay of potassium-40. The various isotopes of radon, all having short half-Hves, are formed by the radioactive decay of radium, actinium, and thorium. Krypton and xenon are products of uranium and plutonium fission, and appreciable quantities of both are evolved during the reprocessing of spent fuel elements from nuclear reactors (qv) (see Radioactive tracers). 

Ra.don Sepa.ra.tion, Owing to its short half-life, radon is normally prepared close to the point of use in laboratory-scale apparatus. Radium salts are dissolved in water and the evolved gases periodically collected. The gas that contains radon, hydrogen, and oxygen is cooled to condense the radon, and the gaseous hydrogen and oxygen are pumped away. 

R. Patel and D. Clifford, Radium Removalfrom Water by Manganese Dioxide Adsorption and Diatomaceous Earth Filtration, NTIS PB92-115260/AS, Springfield, Va., 1992. 

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