Periodic Table -> Fermium
Fermium DetailsFermium Symbol:
FmFermium Atomic Number:
100Fermium Atomic Weight:
(257)What is Fermium?
is a synthetic element with atomic number 100 and the symbol Fm. Fm is part of the actinide series. Of all the elements
that are formed by bombarding light elements with neutrons, it is the heaviest. It has 19 isotopes. The isotope fermium-257 has the longest half-life of all - 100.5 days. This element is highly radioactive, toxic, and risky to handle.
The element Fm was named after the nuclear physicist Enrico Fermi. It is one of the elements that were found to be by-products of the hydrogen bomb explosion in 1952. It is a typical actinide chemically, found in both +3 and +2 oxidation states. Due to the small amounts of this element that are produced and its easy self-disintegration, it is used for little else than basic scientific research. While fermium is not produced commercially, it may have uses in medicine in the future.
Fermium has not been produced in sufficient quantities so far as to analyze its properties. Researchers predict that it is a slivery-colored metal, which is susceptible to attack by acids, steam, and air. In an aqueous environment, only the three oxidation state exists.
While fermium does not occur in nature, it has occurred in the past. It does not pose health hazards as it is not found in the earth’s crust. In terms of annual production, it amounts to no more than milllonth of a gram.
The various isotopes of fermium have atomic weights varying from 242 to 260. They include fermium-253 with a half-life of 3 days, fermium-251 with a half-life of just 5.3 hours, fermium-252 of 25.4 hours, fermium-254 of 3.2 hours, and fermium-256 with a half-life 2.6 hours. The rest have half-lives from half an hour to less than one millisecond. The most stable isotope of fermium is fermium-257, which decays via spontaneous fission or through alpha decay into californium-253. Similar to other synthetic elements, fermium isotopes are highly toxic and very radioactive.
Fermium is not found in nature independently, but always in combination with other elements. It is generated synthetically in a nuclear reactor. The heaviest isotope, fermium-257, with the longest half-life, can only be created in very, very small amounts. After it is produced, fermium has to be separated from the other elements in the actinide series and from other lanthanides. This can be done by means of a process called ion exchange chromatography. This is where a cation exchanger is mixed in with ammonium alpha-hydroxyisobutyrate. The element crystallizes and breaks off.
The nuclear fallout in 1952 was thoroughly analyzed for all kinds of trans-uranium elements. These studies were held because multiple neurons have to be captured in order to synthesize such elements from uranium. Nuclear explosions result in a very powerful surge of neutron production and provide fertile ground for such studies. In fact, around 1029 neutrons are found per cm². Fm was the heaviest element found. Studies were held in Nevada a decade later after a controlled explosion in a confined space took place. The results from these studies were somewhat disappointing because it proved hard to isolate the elements discovered. This is because the explosion drove the majority of them deep underground – up to 600 meters – and it took a long time and a lot of money to drill to such depths.
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