Radium (pronEng|ˈreɪdiəm) is a radioactive
chemical elementwhich has the symbol Ra and atomic number88. Its appearance is almost pure white, but it readily oxidizes on exposure to air, turning black. Radium is an alkaline earth metalthat is found in trace amounts in uraniumores. It is extremely radioactive. Its most stable isotope, SimpleNuclide|Radium|226, has a half-lifeof 1602 years and decays into radongas.
The heaviest of the
alkaline earth metals, radium is intensely radioactive and resembles bariumin its chemical behavior. This metal is found in tiny quantities in the uranium ore pitchblende, and various other uranium minerals. Radium preparations are remarkable for maintaining themselves at a higher temperaturethan their surroundings, and for their radiations, which are of three kinds: alpha particles, beta particles, and gamma rays. Radium also produces neutrons when mixed with beryllium.
When freshly prepared, pure radium metal is brilliant white, but blackens when exposed to air (probably due to
nitrideformation). Radium is luminescent (giving a faint blue color), reacts violently with waterand oilto form radium hydroxide and is slightly more volatile than barium. The normal phase of radium is a solid.
Some of the few practical uses of radium are derived from its radioactive properties. More recently discovered
radioisotopes, such as SimpleNuclide|link|Cobalt|60 and SimpleNuclide|link|Caesium|137, are replacing radium in even these limited uses because several of these isotopes are more powerful emitters, safer to handle, and available in more concentrated form.
When mixed with
berylliumit is a neutron sourcefor physicsexperiments.
Radium was formerly used in self-luminous paints for watches, nuclear panels, aircraft switches, clocks, and instrument dials. More than 100 former watch dial painters who used their lips to shape the paintbrush died from the radiation from the radium that had become stored in their bones. Soon afterward, the adverse effects of radioactivity became widely known. Radium was still used in dials as late as the 1950s. Although tritium's
beta radiationis potentially dangerous if ingested, it has replaced radium in these applications.
During the 1930s it was found that workers' exposure to radium by handling luminescent paints caused serious health effects which included sores,
anemiaand bone cancer. This use of radium was stopped soon afterward. This is because radium is treated as calciumby the body, and deposited in the bones, where radioactivity degrades marrow and can mutate bone cells. The litigation and ultimate deaths of five "Radium Girl" employees who had used radium-based luminous paints on the dials of watches and clocks had a significant impact on the formulation of occupational disease labor law. [ [http://www.radford.edu/~wkovarik/envhist/radium.html Mass Media & Environmental Conflict - Radium Girls ] ]
Radium was also put in some foods for taste and as a preservative, but also exposed many people to radiation. Radium was once an additive in products like toothpaste, hair creams, and even food items due to its supposed curative powers. Such products soon fell out of vogue and were prohibited by authorities in many countries, after it was discovered they could have serious adverse health effects. (See for instance "
Radithor".) Spas featuring radium-rich water are still occasionally touted as beneficial, such as those in Misasa, Tottori, Japan.
Radium (usually in the form of
radium chloride) is used in medicineto produce radongas which in turn is used as a cancertreatment.Fact|date=September 2008 The isotope SimpleNuclide|Radium|223 is currently under investigation for use in medicineas cancertreatment of bone metastasis.
Latin"radius", ray) was discovered by Marie Skłodowska-Curieand her husband Pierre in 1898 in pitchblende from North Bohemia, in the Czech Republic (area around Jáchymov). While studying pitchblende the Curies removed uraniumfrom it and found that the remaining material was still radioactive. They then separated out a radioactive mixture consisting mostly of bariumwhich gave a brilliant green flame color and crimson carmine spectral lines which had never been documented before. The Curies announced their discovery to the French Academy of Scienceson 26 December 1898.
In 1902, radium was isolated as a pure
metalby Curie and André-Louis Debiernethrough the electrolysisof a pure radium chloridesolution by using a mercury cathodeand distilling in an atmosphere of hydrogengas.
Historically the decay products of radium were known as radium A, B, C, etc. These are now known to be isotopes of other elements as follows:
February 4, 1936radium E became the first radioactiveelement to be made synthetically. [cite journal | journal=Phys Rev | volume=50 | issue=5 | pages=425-434 | date=1936 | author=J. J. Livingood | title=Deuteron-Induced Radioactivities | doi = 10.1103/PhysRev.50.425 ]
One unit for radioactivity, the non-
SI curie, is based on the radioactivity of 226Ra (see Radioactivity).
Radium is a
decay productof uranium and is therefore found in all uranium-bearing ores. (One metric tonof pitchblende yields 0.0001 grams of radium). Radium was originally acquired from pitchblende ore from Joachimsthal, Bohemia, in the Czech Republic. Carnotitesands in Coloradoprovide some of the element, but richer ores are found in the Democratic Republic of the Congoand the Great Lakes area of Canada, and can also be extracted from uranium processing waste. Large radium-containing uranium deposits are located in Canada ( Ontario), the United States ( New Mexico, Utah, and Virginia), Australia, and in other places.
Its compounds color flames crimson carmine (rich red or crimson color with a shade of purple) and give a characteristic spectrum. Due to its geologically short
half lifeand intense radioactivity, radium compounds are quite rare, occurring almost exclusively in uranium ores.
"See also ."
Radium (Ra) has 25 different known
isotopes, four of which are found in nature, with 226Ra being the most common. 223Ra, 224Ra, 226Ra and 228Ra are all generated naturally in the decay of either Uranium(U) or Thorium(Th). 226Ra is a product of 238U decay, and is the longest-lived isotope of radium with a half-lifeof 1602 years; next longest is 228Ra, a product of 232Th breakdown, with a half-life of 6.7 years.
Radium is over one million times more radioactive than the same mass of
uranium. Its decay occurs in at least seven stages; the successive main products have been studied and were called radium emanation or exradio (now identified as radon), radium A ( polonium), radium B ( lead), radium C ( bismuth), etc. Radonis a heavy gas and the later products are solids. These products are themselves radioactive elements, each with an atomic weight a little lower than its predecessor.
Radium loses about 1% of its activity in 25 years, being transformed into elements of lower atomic weight with
leadbeing the final product of disintegration.
The SI unit of radioactivity is the
becquerel(Bq), equal to one disintegration per second. The curieis a non-SI unit defined as that amount of radioactivity which has the same disintegration rate as 1 gram of Ra-226 (3.7 x 1010 disintegrations per second, or 37 GBq).
Handling of radium has been blamed for
Marie Curie's premature death.
*Radium is highly radioactive and its decay product, radon gas, is also radioactive. Since radium is chemically similar to calcium, it has the potential to cause great harm by replacing it in
bones. Inhalation, injection, ingestion or body exposure to radium can cause cancer and other disorders. Stored radium should be ventilated to prevent accumulation of radon.
*Emitted energy from the decay of radium ionizes gases, affects photographic plates, causes sores on the skin, and produces many other detrimental effects.
* Scientific American ("Macklis RM, The great radium scandal. Sci.Am. 1993 Aug: 269(2):94-99")
* Clark, Claudia. (1987). "Radium Girls: Women and Industrial Health Reform, 1910-1935". University of North Carolina Press. ISBN 0-8078-4640-6.
* Ken Silverstein, "Harper's Magazine", November 1998; The radioactive boy scout: when a teenager attempts to build a breeder reactor - case of David Hahn who managed to secure materials and equipment from businesses and information from government officials to develop an atomic energy radiation project for his Boy Scout merit-badge.
Decay chains (with some examples including Radium)
* [http://www.webelements.com/webelements/elements/text/Ra/index.html WebElements.com - Radium] (also used as a reference)
* [http://www.lateralscience.co.uk/radium/RaDisc.html Lateral Science - Radium Discovery]
* [http://www.markwshead.com/stuffHappens/radium.html Photos of Radium Water Bath in Oklahoma]
* [http://toxnet.nlm.nih.gov/cgi-bin/sis/search/r?dbs+hsdb:@term+@na+@rel+radium,+radioactive NLM Hazardous Substances Databank – Radium, Radioactive]
Wikimedia Foundation. 2010.
Look at other dictionaries:
RADIUM — En 1898, quelques mois après avoir découvert le polonium, Pierre et Marie Curie et leur collaborateur Gustave Bémont, poursuivant l’étude du fractionnement de la pechblende de Joachimsthal (aujourd’hui Jáchymov, en République tchèque), purent… … Encyclopédie Universelle
Radium — Ra di*um (r[=a] d[i^]*[u^]m), n. [NL., fr. L. radius ray.] (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… … The Collaborative International Dictionary of English
Radium  — Radium, ein von dem Ehepaar Curie zuerst isoliertes Element, das mit Baryum große Aehnlichkeit zeigt. Durch Bestimmung des Chlorsilbers, das aus dem bei 100° getrockneten Radiumchlorid erhalten werden konnte, und unter der Annahme der Formel… … Lexikon der gesamten Technik
Radium — Sn (radioaktives Erdalkalimetall) per. Wortschatz fach. (20. Jh.) Neoklassische Bildung. Entdeckt und bezeichnet von den französischen Physikern M. und P. Curie. Zu l. radius Strahl als das Strahlende . Ebenso nndl. radium, ne. radium, nfrz.… … Etymologisches Wörterbuch der deutschen sprache
Radium  — Radium. Die Lehre von der atomaren Struktur der Elektrizität, die Elektronentheorie, und die aus ihr sich ergebende Definition der »korpuskularen Strahlungen« ebneten den Weg zu einem besseren, umfassenderen Verständnis der… … Lexikon der gesamten Technik
Radium — Студийный альбом Ruoska Дата выпуска 22 марта 2005 Жанр Industrial metal Neue Deutsche Härte Лейбл Kråklund Records П … Википедия
Radium — Radium, KS U.S. city in Kansas Population (2000): 40 Housing Units (2000): 19 Land area (2000): 0.041442 sq. miles (0.107335 sq. km) Water area (2000): 0.000000 sq. miles (0.000000 sq. km) Total area (2000): 0.041442 sq. miles (0.107335 sq. km)… … StarDict's U.S. Gazetteer Places
Radium, KS — U.S. city in Kansas Population (2000): 40 Housing Units (2000): 19 Land area (2000): 0.041442 sq. miles (0.107335 sq. km) Water area (2000): 0.000000 sq. miles (0.000000 sq. km) Total area (2000): 0.041442 sq. miles (0.107335 sq. km) FIPS code:… … StarDict's U.S. Gazetteer Places
Radĭum — Ra, chemisches Element, ist bisher nur als Begleiter des Urans in Mineralien aufgefunden worden, und zwar scheint der Gehalt der Gesteine an R. direkt von ihrem Urangehalt abhängig zu sein. Wahrscheinlich ist R. spurenweise überall in der festen… … Meyers Großes Konversations-Lexikon
radium — RÁDIUM s.n. v. radiu. Trimis de LauraGellner, 13.09.2007. Sursa: DEX 98 RÁDIUM s.n. v. radiu. Trimis de LauraGellner, 13.09.2007. Sursa: DN … Dicționar Român