Actinium



89 thorium
Ute
General
Number actinium, Ac, 89
actinides
Block f
Appearance silvery
Standard atomic weight (227)  g·mol−1
Rn] 6d1 7s2
shell 2, 8, 18, 32, 18, 9, 2
Physical properties
Phase solid
r.t.) 10  g·cm−3
F)
F)
kJ·mol−1
kJ·mol−1
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 (atomic number 89.

Contents

Notable characteristics

Actinium is a silvery, 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 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 lanthanum.

The word actinium comes from the Greek aktis, aktinos, meaning beam or ray.

Occurrence

Actinium is found in trace amounts in Ra in a nuclear reactor. Actinium metal has been prepared by the reduction of actinium fluoride with lithium vapor at about 1100 to 1300ºC.

Isotopes

Main article: isotopes of actinium

Naturally occurring actinium is composed of 1 radioactive 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 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.[citation needed]

References

  • Los Alamos National Laboratory - Actinium
 
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