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Americium

Americium is a synthetic element in the periodic table that has the symbol Am and atomic number 95. A radioactive Radioactive decay

Radioactive decay is the set of various processes by which unstable atomic nuclei [i] ... 

 metal Metal

In chemistry, a metal is an element [i] that readily forms positive ion [i]s and has ... 

lic element, americium is an actinide Actinide

The actinide series encompasses the 15 chemical element [i]s that lie between actinium [i] and lawrencium [i] ... 

 that was obtained by bombarding plutonium Plutonium

Plutonium is a radioactive [i], metal [i]lic chemical element [i]. ... 

 with neutron Neutron

In physics [i], the neutron is a subatomic particle [i] with no net electric charge [i] and a mass [i] o ... 

s and was the fourth transuranic element Transuranium element

In chemistry [i], transuranium elements are the chemical element [i]s with atomic number [i]s greater t ... 

 to be discovered. It was named for the Americas Americas

he Americas are the lands of the Western hemisphere [i] or New World [i] consisting o ... 

, by analogy with europium.

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Encyclopedia

Americium is a synthetic element in the periodic table that has the symbol Am and atomic number 95. A radioactive Radioactive decay

Radioactive decay is the set of various processes by which unstable atomic nuclei [i] ... 

 metal Metal

In chemistry, a metal is an element [i] that readily forms positive ion [i]s and has ... 

lic element, americium is an actinide Actinide

The actinide series encompasses the 15 chemical element [i]s that lie between actinium [i] and lawrencium [i] ... 

 that was obtained by bombarding plutonium Plutonium

Plutonium is a radioactive [i], metal [i]lic chemical element [i].... 

 with neutron Neutron

In physics [i], the neutron is a subatomic particle [i] with no net electric charge [i] and a mass [i] o ... 

s and was the fourth transuranic element Transuranium element

In chemistry [i], transuranium elements are the chemical element [i]s with atomic number [i]s greater t ... 

 to be discovered. It was named for the Americas Americas

he Americas are the lands of the Western hemisphere [i] or New World [i] consisting o ... 

, by analogy with europium.

Notable characteristics

Freshly prepared americium metal Metal

In chemistry, a metal is an element [i] that readily forms positive ion [i]s and has ... 

 has a white and silvery lustre, at room temperatures it slowly tarnishes in dry air. It is more silvery than plutonium Plutonium

Plutonium is a radioactive [i], metal [i]lic chemical element [i].... 

 or neptunium and apparently more malleable than neptunium or uranium Uranium

Uranium is a chemical element [i] in the periodic table [i] that has the symbol U and atomic number [i] ... 

. Alpha emission from 241Am is approximately three times that of radium. Gram Gram

The gram or gramme symbol g, is a unit [i] of mass [i].
... 

 quantities of 241Am emit intense gamma ray Gamma ray

Gamma rays are an energetic form of electromagnetic radiation [i] produced by radioactive decay [i] or ... 

s which creates a serious exposure problem for anyone handling the element.

Please see Actinides in the environment Actinides in the environment

This article about actinides in the environment is about the sources, environmental behaviour and effect... 

 for details of the environmental aspects of this element.

Applications

This element can be produced in kilogram Kilogram

The kilogram or kilogramme, is the SI base unit [i] of mass [i]. ... 

 amounts and has some uses . Americium has found its way into the household, where one type of smoke detector Smoke detector

A smoke detector or smoke alarm is an active fire protection [i] device, subject to stringent bounding [i] ... 

 contains a tiny amount of 241Am as a source of ionizing radiation Ionizing radiation

Ionizing radiation has many practical uses, but it is also dangerous to human health.... 

. 241Am has been used as a portable gamma ray source for use in radiography. The element has also been employed to gauge glass Glass

Glass is a uniform amorphous solid [i] material, usually produced when the viscous molten material cools ... 

 thickness to help create flat glass. 242Am is a neutron emitter and has found uses in neutron radiography. However this isotope is extremely expensive to produce in usable quantities.

History

Americium was first synthesized by Glenn T. Seaborg Glenn T. Seaborg

Glenn Theodore Seaborg was an American [i] chemist [i] prominent in the discovery and iso ... 

, Leon O. Morgan, Ralph A. James, and Albert Ghiorso in late 1944 at the wartime Metallurgical Laboratory at the University of Chicago University of Chicago

The University of Chicago is a private university [i] located principally in the Hyde Park [i]... 

 . The team created the isotope 241Am by subjecting 239Pu Plutonium

Plutonium is a radioactive [i], metal [i]lic chemical element [i].... 

 to successive neutron capture reactions in a nuclear reactor Nuclear reactor

A nuclear reactor is a device in which nuclear chain reaction [i]s are initiated, controlled, and sustai ... 

. This created 240Pu and then 241Pu which in turn decayed into 241Am via beta decay Beta decay

In nuclear physics [i], beta decay is a type of radioactive [i] decay in which a beta particle [i] is e ... 

. Seaborg was granted patent Patent

A patent is a set of exclusive right [i]s granted by a state [i] to a patentee for a fixed period of time [i] ... 

 3,156,523 for "Element 95 and Method of Producing Said Element". The discovery of americium and curium was first announced informally on a children's quiz show in 1945.

Isotopes

18 radioisotope Radionuclide

Atoms of chemical elements may have many isotopes with the same atomic numbers but different atomic weights /... 

s of americium have been characterized, with the most stable being 243Am with a half-life of 7370 years, and 241Am with a half-life of 432.2 years. All of the remaining radioactive Radioactive decay

Radioactive decay is the set of various processes by which unstable atomic nuclei [i] ... 

 isotopes have half-lives that are less than 51 hours, and the majority of these have half-lives that are less than 100 minutes. This element also has 8 meta states, with the most stable being 242mAm . The isotopes of americium range in atomic weight from 231.046 amu  to 249.078 amu .

Chemistry


In aqueous systems the most common oxidation state is +3, it is very much harder to oxidise Am to Am than it is to do the same oxidation for Pu.

Currently the solvent extraction chemistry of americium is important as in several areas of the world scientists Scientist

A scientist is an expert [i] in at least one area of science [i] who uses the scientific method [i] to d ... 

 are working on reducing the medium term radiotoxicity of the waste from the reprocessing of used nuclear fuel Nuclear fuel

Nuclear fuel is any material that can be consumed to derive nuclear energy [i], by analogy to chemical fuel [i] ... 

.

See liquid-liquid extraction for some examples of the solvent extraction of americium.

Americium unlike uranium does not readily form a dioxide americyl core , this is because americium is very hard to oxidise about the +3 oxidation state when it is in an aqeuous solution. In the environment, this americyl core could complex with carbonate as well as other oxygen moeities to form charged complexes which tend to be readily mobile with low affinities to soil.

  • AmO2+1
  • AmO22+2
  • AmO21+1
  • AmO22-1
  • AmO23-3

References

  • Guide to the Elements - Revised Edition, Albert Stwertka, ISBN 0-19-508083-1


External links