Actinium

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89 radium ← actinium → thorium La ↑ Ac ↓ Ute Periodic Table - Extended Periodic Table
General
Name, Symbol, Number	actinium, Ac, 89
Chemical series	actinides
Group, Period, Block	3, 7, f
Appearance	silvery
Standard atomic weight	(227)  g·mol−1
Electron configuration	[Rn] 6d1 7s2
Electrons per shell	2, 8, 18, 32, 18, 9, 2
Physical properties
Phase	solid
Density (near r.t.)	10  g·cm−3
Melting point	(circa) 1323 K (1050 °C, 1922 °F)
Boiling point	3471 K (3198 °C, 5788 °F)
Heat of fusion	14  kJ·mol−1
Heat of vaporization	400  kJ·mol−1
Specific heat capacity	(25 °C) 27.2  J·mol−1·K−1
Atomic properties
Crystal structure	cubic face centered
Oxidation states	3 (neutral oxide)
Electronegativity	1.1 (Pauling scale)
Ionization energies	1st: 499 kJ/mol
	2nd: 1170 kJ/mol
Atomic radius	195  pm
Miscellaneous
Magnetic ordering	no data
Thermal conductivity	(300 K) 12  W·m−1·K−1
CAS registry number	7440-34-8
Selected isotopes
Main article: Isotopes of actinium iso NA half-life DM DE (MeV) DP 225Ac syn 10 days α 5.935 221Fr 226Ac syn 29.37 hours β- 1.117 226Th ε 0.640 226Ra α 5.536 222Fr 227Ac 100% 21.773 years β- 0.045 227Th α 5.042 223Fr
References

Actinium (pronounced /ækˈtɪniəm/) is a chemical element with the symbol Ac and atomic number 89.

Contents 1 Notable characteristics 2 Applications 3 History 4 Occurrence 5 Isotopes 6 Precautions 7 Fictional Applications 8 See also 9 References 10 External links

[edit] Notable 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 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. ²³⁵U (or ²³⁹Pu) is the parent isotope of the actinium series decay chain which ends with the stable isotope ²⁰⁷Pb.

[edit] 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 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.

[edit] 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)^[1] or similar to thorium (1890)^[2]. Friedrich Oskar Giesel independently discovered actinium in 1902^[3] as a substance being similar to lanthanum and called it "emanium" in 1904^[4]. After a comparison of substances in 1904, Debierne's name was retained because it had seniority.^[5][6]

The history of the discovery stayed questionable and in publications from 1971^[7] and later in 2000^[8] 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.

[edit] 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 1300°C.

[edit] Isotopes

Main article: isotopes of actinium

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).

[edit] 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.^{[citation needed]}

[edit] Fictional Applications

Actinium compounds, along with advanced circuitry are used in a time travel device in Excalibur: Morgana's Revenge

[edit] See also

• Actinium series

[edit] References

• Los Alamos National Laboratory - Actinium

[edit] External links

• WebElements.com - Actinium
• NLM Hazardous Substances Databank – Actinium, Radioactive

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Fr	Ra	Ac	Th	Pa	U	Np	Pu	Am	Cm	Bk	Cf	Es	Fm	Md	No	Lr	Rf	Db	Sg	Bh	Hs	Mt	Ds	Rg	Uub	Uut	Uuq	Uup	Uuh	Uus	Uuo
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