Actinium

Actinium (pronEng|ækˈtɪniəm) is a radioactive chemical element with the symbol Ac and atomic number 89, which was discovered in 1899, the earliest discovered of the radioactive elements.

Characteristics

Actinium is a silvery, radioactive, metallic element. Due to its intense radioactivity, actinium glows in the dark with a pale blue light. The chemical behavior of actinium is similar to that of the rare earth element lanthanum.

Actinium 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. The actinium isotope 227Ac is a transient member of the actinium series decay chain, which begins with the parent isotope 235U (or 239Pu) and ends with the stable lead isotope 207Pb. Another actinium isotope (225Ac) is transiently present in the neptunium series decay chain, beginning with 237Np (or 233U) and ending with near-stable bismuth (209Bi).

Applications

It is about 150 times as radioactive as radium, making it valuable as a neutron source for energy. Otherwise it has no significant industrial applications.

225Ac is used in medicine to produce 213bismuth in a reusable generator or can be used alone as an agent for radio-immunotherapy for Targeted Alpha Therapy (TAT). 225Ac was first produced artificially by the ITU in Germany using a cyclotron and by Dr Graeme Melville at St George Hospital in Sydney using a linac in 2000.

History

Actinium was discovered in 1899 by André-Louis Debierne, a French chemist, who separated it from pitchblende as a substance being similar to titanium (1899) [cite journal
title = Sur un nouvelle matière radio-active
author = André-Louis Debierne
journal = Comptes rendus
volume = 129
issue =
pages = 593–595
year = 1899
url = http://gallica.bnf.fr/ark:/12148/bpt6k3085b/f593.table
doi =
] or similar to thorium (1890) [cite journal
title = Sur un nouvelle matière radio-actifl'actinium
author = André-Louis Debierne
journal = Comptes rendus
volume = 130
issue =
pages = 906–908
year = 1900
url = http://gallica.bnf.fr/ark:/12148/bpt6k3086n/f906.table
doi =
] . Friedrich Oskar Giesel independently discovered actinium in 1902 [cite journal
title = Ueber Radium und radioactive Stoffe
author = Friedrich Oskar Giesel
journal = Berichte der Deutschen Chemische Geselschaft
volume = 35
issue = 3
pages = 3608–3611
year = 1902
url =
doi = 10.1002/cber.190203503187
] as a substance being similar to lanthanum and called it "emanium" in 1904 [cite journal
title = Ueber den Emanationskörper (Emanium)
author = Friedrich Oskar Giesel
journal = Berichte der Deutschen Chemische Geselschaft
volume = 37
issue = 2
pages = 1696–1699
year = 1904
url =
doi = 10.1002/cber.19040370280
] . After a comparison of substances in 1904, Debierne's name was retained because it had seniority. [cite journal
title = Ueber Emanium
author = Friedrich Oskar Giesel
journal = Berichte der Deutschen Chemische Geselschaft
volume = 37
issue = 2
pages = 1696–1699
year = 1904
url =
doi = 10.1002/cber.19040370280
] [cite journal
title = Ueber Emanium
author = Friedrich Oskar Giesel
journal = Berichte der Deutschen Chemische Geselschaft
volume = 38
issue = 1
pages = 775–778
year = 1905
url =
doi = 10.1002/cber.190503801130
]

The history of the discovery stayed questionable and in publications from 1971 [cite journal
title = The Discovery of Actinium
author = H. W. Kirby
journal = Isis
volume = 62
issue = 3
pages = 290–308
year = 1971
url = http://www.jstor.org/stable/view/229943?seq=1
doi =
] and later in 2000 [cite journal
title = The centenary of a controversial discovery: actinium
author = J. P. Adloff
journal = Radiochim. Acta,
volume = 88
issue =
pages = 123
year = 2000
url =
doi = 10.1524/ract.2000.88.3-4.123
] showed that the claims of André-Louis Debierne in 1904 conflict with the publications in 1899 and 1890.

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 226radium in a nuclear reactor. Actinium metal has been prepared by the reduction of actinium fluoride with lithium vapor at about 1100 to 1300°C.

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 u (206Ac) to 236 u (236Ac).

Precautions

227Ac is extremely radioactive, and in terms of its potential for radiation induced health effects, 227Ac is even more dangerous than plutonium. Ingesting even small amounts of 227Ac would be fatal.Fact|date=November 2007

Fictional Applications

Actinium compounds, along with advanced circuitry are used in a time travel device in

ee also

*Actinium series

References

* [http://periodic.lanl.gov/elements/89.html Los Alamos National Laboratory - Actinium]

External links

* [http://www.webelements.com/webelements/elements/text/Ac/index.html WebElements.com - Actinium]
* [http://toxnet.nlm.nih.gov/cgi-bin/sis/search/r?dbs+hsdb:@term+@na+@rel+actinium,+radioactive NLM Hazardous Substances Databank – Actinium, Radioactive]


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  • ACTINIUM — L’existence dans la pechblende de l’actinium, élément radioactif de numéro atomique 89, fut établie en 1899 par André Louis Debierne, collaborateur de Pierre et Marie Curie qui venaient, un an auparavant, de découvrir, dans ce minerai d’uranium,… …   Encyclopédie Universelle

  • Actinium — Radium ← Actinium → Thorium La …   Wikipédia en Français

  • Actinium — Ac*tin i*um, n. [Gr. ?, ?, ray.] (Chem.) A supposed metal, said by Phipson to be contained in commercial zinc; so called because certain of its compounds are darkened by exposure to light. [1913 Webster] …   The Collaborative International Dictionary of English

  • actinium — ACTÍNIUM s.n. v. actiniu. Trimis de LauraGellner, 13.09.2007. Sursa: DN …   Dicționar Român

  • actinium — Symbol: Ac Atomic number: 89 Atomic weight: (227) Silvery radioactive metallic element, belongs to group 3 of the periodic table. The most stable isotope, Ac 227, has a half life of 217 years. Ac 228 (half life of 6.13 hours) also occurs in… …   Elements of periodic system

  • actinium — (n.) radioactive element discovered in 1899, from Gk. actin , comb. form of aktis (gen. aktinos) ray, radiance (see ACTINO (Cf. actino )) + chemical suffix ium …   Etymology dictionary

  • actinium — [ak tin′ē əm] n. [ModL < ACTINO + IUM] a white, radioactive, metallic chemical element, the first member of the actinide series, found in pitchblende and other minerals or formed in reactors by the neutron irradiation of radium: symbol, Ac; at …   English World dictionary

  • Actinium — Eigenschaften …   Deutsch Wikipedia

  • actinium — /ak tin ee euhm/, n. Chem. a radioactive silver white metallic element that glows blue in the dark, resembling the rare earths in chemical behavior and valence. Symbol: Ac; at. no.: 89; at. wt.: 227. [1900 05; ACTIN + IUM] * * * ▪ chemical… …   Universalium

  • Actinium — Ac|ti|ni|um 〈n.; s; unz.; chem. 〉 = Aktinium * * * Ac|ti|ni|um [griech. aktís, Gen.: akti̅nos = Strahl; ↑ ium (1)], das; s; Symbol: Ac: radioaktives, natürlich vorkommendes chem. Element aus Gruppe 3 des Periodensystems, das oft als Anfangsglied… …   Universal-Lexikon

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