Actinium
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Actinium is a chemical element in the periodic table that has the symbol Ac and atomic number 89.
Contents |
Notable characteristics
Actinium is a silvery radioactive metallic element. Due to its intense radioactivity, Actinium glows in the dark with an eerie blue light. It is found only in traces in uranium ores as 227Ac, an α and β emitter with a half-life of 21.773 years. One ton of uranium ore contains about a tenth of a gram of actinium.
Applications
It is about 150 times as radioactive as radium, making it valuable as a neutron source. Otherwise it has no significant industrial applications.
225Ac is used in medicine to produce 213Bi in a reusable generator or can be used alone as an agent for radio-immunotherapy.
History
Actinium was discovered in 1899 by André-Louis Debierne, a French chemist, who separated it from pitchblende. Friedrich Otto Giesel independently discovered actinium in 1902. The chemical behavior of actinium is similar to that of the rare earth lanthanum.
The word actinium comes from the Greek aktis, aktinos, meaning beam or ray.
Occurrence
Actinium is found in trace amounts in uranium ore, but more commonly is made in milligram amounts by the neutron irradiation of 226Ra in a nuclear reactor. Actinium metal has been prepared by the reduction of actinium fluoride with lithium vapor at about 1100 to 1300ºC.
Isotopes
Naturally occurring actinium is composed of 1 radioactive isotope; 227Ac. 36 radioisotopes have been characterized with the most stable being 227Ac with a half-life of 21.772 y, 225Ac with a half-life of 10.0 days, and 226Ac with a half-life of 29.37 h. All of the remaining radioactive isotopes have half-lifes that are less than 10 hours and the majority of these have half lifes that are less than 1 minute. The shortest-lived isotope of actinium is 217Ac which decays through alpha decay and electron capture. It has a half-life of 69 ns. Actinium also has 2 meta states.
Purified 227Ac comes into equilibrium with its decay products at the end of 185 days, and then decays according to its 21.773-year half-life.
The isotopes of actinium range in atomic weight from 206 amu (206Ac) to 236 amu (236Ac).
Precautions
227Ac is extremely radioactive, and in terms of its potential for radiation induced health effects, 227Ac is about as dangerous as plutonium. Ingesting even small amounts of 227Ac would present a serious health hazard.
References
External links
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ca:Actini cs:Aktinium da:Actinium de:Actinium et:Aktiinium es:Actinio eo:Aktinio fr:Actinium he:אקטיניום hr:Aktinij ko:악티늄 io:Aktiniumo it:Attinio la:Actinium lt:Aktinis hu:Aktínium nl:Actinium ja:アクチニウム no:Actinium nn:Actinium pl:Aktyn pt:Actínio ru:Актиний sr:Актинијум fi:Aktinium sv:Aktinium th:แอกทิเนียม uk:Актиній zh:锕