Fermium (Fm)
Fermium (Fm), with the atomic number 100, is a synthetic radioactive element that belongs to the actinide series in the periodic table. It was named in honor of the renowned physicist Enrico Fermi and was first discovered in the debris of the 1952 hydrogen bomb test, known as "Ivy Mike." Despite its fascinating origins, many of fermium's physical and chemical properties remain largely unknown due to its rapid decay and the complexities involved in producing it. The most stable isotope, fermium-257, has a half-life of 100.5 days, while fermium-255, which is more commonly studied, has a half-life of just over 20 hours.
Fermium typically exists in a +3 oxidation state, and it is theorized to be a solid metal at standard temperature. As a rare earth metal, it lacks biological significance and is considered toxic due to its radioactivity. Currently, fermium is primarily utilized for scientific research, with an annual production of about a millionth of a gram, and has no commercially important compounds or applications. Overall, fermium serves as an intriguing element within the realm of nuclear science and research, reflecting both the advancements in atomic theory and the challenges posed by synthetic elements.
Fermium (Fm)
- Element Symbol: Fm
- Atomic Number: 100
- Atomic Mass: 257
- Group # in Periodic Table: n/a
- Group Name: Actinides
- Period in Periodic Table: 7
- Block of Periodic Table: f-block
- Discovered by: Albert Ghiorso, Torbjørn Sikkeland, Almon E. Larsh, Robert M. Latimer (1952)
Fermium, with atomic number 100 and symbol Fm, is found in Block F of Period 7 in the periodic table, and it belongs to the actinide series. Fermium is a radioactive element and is produced artificially.
Fermium was named after the Italian physicist and Nobel laureate Enrico Fermi. While teaching and doing research at the University of Rome from 1926 to 1938, Fermi discovered how to effectively use neutrons to change elements from one isotope to another. In 1952, the 10-megaton, "Ivy Mike" nuclear test was conducted in the South Pacific. Later in that same year, American nuclear scientist Albert Ghiorso led a team of scientists from the Lawrence Berkeley National Laboratory, the Argonne National Laboratory, and the Los Alamos Scientific Laboratory that studied the radioactive debris that was produced by the detonation of the first hydrogen bomb. Uranium-230 had been used in that test to set off a thermonuclear explosion. During its study, the team discovered an isotope, fermium-255, that had a half-life 20.7 hours.
In 1954, researchers from the Nobel Institute of Physics in Stockholm bombarded uranium-238 with oxygen-16 ions. In doing so, they produced fermium-250. The discovery of fermium was kept a secret, however, until 1955 due to Cold War tensions. The name fermium (Fm) was then formally accepted by the International Union of Pure and Applied Chemistry (IUPAC).
Physical Properties
Because fermium is a radioactive element, one that decays quickly and is artificially produced, many of its physical and chemical properties remain a mystery. For example, the boiling point of fermium is unknown, but its freezing point is 2781°F (1527°C). The standard state of an element is defined as its state at 298 kelvin (K). It is theorized that fermium is a solid at this temperature. It is classified as a metal. Fermium has one hundred electrons and one hundred protons. It is the eighth synthetic transuranium element of the actinide series to be discovered. It has no compounds derived from it. The density of solid fermium and its appearance are not known.
Chemical Properties
Fermium was produced by combining seventeen neutrons with uranium-238. Fermium was obtained after undergoing a lengthy chain reaction of eight beta decays. The ionization energy of fermium is 627 kilojoules per mole. Its electron shells are 2, 8, 18, 32, 30, 8, 2. The density of fermium at standard temperature and pressure (STP) is unknown. The electronic configuration of fermium is [Rn] 5f127s2. The isotopes of fermium are radioactive by nature and decay via alpha particle emission, electron capture, and instant fission.
Fermium has a typical chemistry in the late actinides with a prevalence of +3 oxidation state, but it also has an obtainable +2 oxidation state. Pure fermium metal has not yet been prepared. There are in all nineteen isotopes of fermium—from atomic weights 242 to 260. The longest-lived isotope is fermium-257 with a half-life of 100.5 days. However, fermium-255. which has a half-life of 20.07 hours, can be easily isolated as the decay product of einsteinium-255, and thus, most studies are conducted on this isotope.
The major source of fermium is the 85 MW High Flux Isotope Reactor (HFIR) that is located at the Oak Ridge National Laboratory in Tennessee. Studying the chemical properties of fermium requires innovative techniques. It has been deduced that fermium metal exhibits a divalent state. The element can also exist in a trivalent state with modest compression.
During the thermonuclear explosion of 1952, the uranium-238 had captured several neutrons that bombarded its nucleus. As a result, elements with atomic numbers 93 to 100 were obtained. Fermium-255 was the last isotope of element 100 to be produced. Researchers believe that fermium is a silvery metal, which can be affected by acid, steam, and air.
After being produced, fermium is separated both from other elements in the actinide series and also from lanthanides by a process called ion exchange chromatography.
Fermium does not bond with rare earth fluorides and hydroxides. In an aqueous solution, fermium exists as the Fm3+ ion. The complexes formed with ligands, such as chloride or nitrate, are more stable than those formed with einsteinium and californium. Through the use of radioelectrochemistry and other techniques, the Fm(III)/Fm(III) reduction-oxidation (redox) couple in aqueous media has also been investigated. All of the chemical information about the element fermium has been obtained from its trace elements.
Applications
Fermium is a rare earth metal. It does not have any biological role since its radioactivity makes it toxic. The ingestion limit of fermium-253 was set at 107 Bq (Becquerel), and the inhalation limit has been set at 105 Bq. For fermium-257, the limits were set at 105 Bq and 4000 Bq, respectively. Fermium is not present in the geosphere because it is a synthetic element. For this reason, fermium is not considered to be an environmental or health hazard. Fermium is used only for scientific research. There are no commercially important compounds of fermium. The annual production of fermium is roughly a millionth of a gram. If allowed to decay for a long time, the element turns to californium, an element that does have many uses.
Bibliography
"Fermium." Periodic Table. The Royal Society of Chemistry, n.d. Web. 15 Jan. 2016.
"Fermium: The Essentials." WebElements. The University of Sheffield and Mark Winter, n.d. Web. 15 Jan. 2016.
"Fermium Elemental Facts." Chemicool. Chemicool.com, n.d. Web. 15 Jan. 2016.
Krebs, Robert E. The History and Use of Our Earth’s Chemical Elements: A Reference Guide. Westport: Greenwood, 1998. Print.
Morss, Lester. "Fermium (Fm)." Encyclopaedia Britannica Online. Encyclopaedia Britannica Inc., n.d. Web. 15 Jan. 2016.